Diseases and their prevention. Infectious diseases - a group of diseases caused by pathogenic or opportunistic microorganisms, characterized by a cyclical process and the formation of specific immunity
Topic: "Infectious diseases and their prevention".
Prepared by: Rashidova H.A.
Goals of the work:
Familiarize yourself with the main types of infectious diseases.
Tasks:
1 . To identify the mechanisms of transmission of infectious diseases.
2. To study measures for the prevention of common infectious diseases.
I .Introduction. The urgency of the problem.
Even in ancient times, various infections horrified mankind, epidemics of various diseases mowed down cities, countries, millions of people died. Entire peoples were on the verge of extinction, the so-called "pestilence" was considered one of the most terrible punishments in the whole world, and measures to combat it were sometimes decisive and merciless. Sometimes huge territories with all people and property were burned out in order to prevent the spread of a deadly disease further. In the modern world, medicine has learned to fight and prevent many of those terrible infections that in the Middle Ages became the scourge of society, which caused some euphoria that swept humanity in the middle of the twentieth century. But the joy of success in the fight against the old diseases was somewhat premature, since they were replaced and continue to come by more and more infectious diseases, potentially capable of destroying a significant number of people.
Throughout the foreseeable history, the greatest scourge for humanity has been plague, smallpox, cholera and yellow fever, which have claimed the lives of a large number of people.
However, the battle against infectious agents is still ongoing and the only infectious disease that has been successfully eradicated in the world is smallpox.
The eradication of other diseases such as tetanus, measles, whooping cough, diphtheria and poliomyelitis, for which effective immunization is quite acceptable on a global scale, has now been achieved by more than 90%.
The high immigration of the population from the countries of the "Third World" has led in industrialized countries to a sharp increase in the number of people suffering from infectious diseases.
While mankind managed to learn how to manage the old epidemics, new ones appeared. Of note is the ongoing epidemic of human immunodeficiency virus (HIV) infection, with devastating consequences not only in Africa and Asia, but also in Europe and North America.
Despite the improvement of living conditions in economically developed countries, the widespread practice of vaccination and the availability of effective antibiotics, infectious diseases still occupy a significant place in the structure of human morbidity and mortality and are second only to diseases of the cardiovascular system and malignant oncological diseases. Most deaths among children are infectious diseases of the respiratory system, intestines, caused by viruses and bacteria.
Hepatitis A is a widespread infectious disease caused by the hepatitis A virus. Periodic rises in incidence are typical, especially in the summer and autumn months.Infectious diseases, as in previous years, continue to occupy one of the leading places among human diseases. The problems of viral hepatitis and acute intestinal infections remain relevant. Long-forgotten diphtheria has returned from past years, new infections caused by herpesviruses, borrelia, chlamydia, etc. have become widespread tuberculosis, and AIDS poses a threat to humanity. In the context of socio-economic shifts that led to the stratification of society, the emergence of a large number of socially unprotected people, many infectious diseases have become severe, often fatal. Influenza and SARS remain one of the most urgent medical and socio-economic problems, and an example of this is the epidemiological situation in our city and in the Saratov region in January-March of this year. I went to polyclinic No. 3 and took data on SARS and influenza for the period from February 4 to 18 and found out that the number of cases during this period was 6884 people, of which 3749 were children. I chose the topic “Infectious Diseases” because I consider this problem to be very important and intractable. After reviewing and reading a large amount of literature on infectious diseases, I decided to tell you about them, as well as their prevention.
II . Main part.
2.1 What are infectious diseases?
Infectious diseases - this is a group of diseases caused by the penetration of pathogenic (pathogenic) microorganisms into the body. In order for the pathogenic microbe to causeinfection , he must havevirulence , that is, the ability to overcome the body's resistance and exhibit a toxic effect. Some pathogenic agents cause poisoning of the body by the exotoxins they secrete during their vital activity (tetanus, diphtheria), others release toxins (endotoxins) when their bodies are destroyed (cholera, typhoid fever).
In the endXVIIIcentury French scientist Louis Pasteur refuted the theory of spontaneous generation of microorganisms. He singled out the causative agents of anthrax, rubella, rabies, and proposed a method for the disinfection of food products (pasteurization). L. Pasteur is rightfully considered the founder of modern microbiology and immunology.
Even Hippocrates drew attention to the fact that diseases are preceded by certain environmental conditions and the state of human health. Infectious diseases can occur in the presence of three components, when there is:
source of infectious agents (infected person or animal);
a factor that ensures the transmission of pathogens from an infected organism to a healthy one;
people susceptible to infection.
The ability to cause disease in different microorganisms is not the same. It determines the ability of pathogens to invade certain organs and tissues, multiply in them and release toxic substances.
2.2 Sanitary and epidemiological situation in the Russian Federation and in the city of Balakovo.
The 20th century gave rise to unjustified optimism that infectious diseases would soon be eradicated. However, the events of recent decades have shown that such infections as tuberculosis, malaria, which are becoming the main cause of death, have sharply intensified in the world; both in Russia and in other countries, diphtheria reappears. The epidemiological situation that has developed in recent years remains tense. From 33 to 44 million cases of infectious diseases are registered annually in the Russian Federation. Influenza and ARVI remain one of the most urgent medical and socio-economic problems. In the period from January to March 2013 in the Saratov region and on the territory of the BIS, there was an excess of the average annual incidence rate of SARS and influenza by 35%.
Viral hepatitis continues to be a serious health problem, damaging both the health of the population and the country's economy.On the territory of the Balakovo municipal district since August 2012. there is a deterioration in the epidemiological situation in the incidence of acute viral hepatitis A
Hepatitis A is a widespread infectious disease caused by the hepatitis A virus. Periodic rises in incidence are typical, especially in the summer and autumn months. For 8 months of 2012, 46 cases of hepatitis A were registered on the territory of the BIS, which is 4.3 times higher than the incidence of hepatitis A in the same period last year. According to operational data, the situation with the incidence of this infection has become more complicated. As of October 18, 2012, 22 more cases were detected. Every day, 2-3 new cases of this disease are registered.
The situation is especially difficult for socially conditioned diseases. Since 1992, the country began to increase the incidence of tuberculosis with an annual increase of 10-15%.
According to the coverage of the population with preventive examinations for tuberculosis in 2012. the figure was 75.5%. To combat this terrible disease, federal and regional programs were adopted, which made it possible to significantly reduce the prevalence of this disease.
The incidence of tuberculosis (in the Saratov region - 61.5 cases per 100 thousand of the population, in Balakovo and Balakovo district 55.9. Compared to 2011, we have seen an increase in the incidence.
The rapid increase in the scale of the pandemic of the disease caused by the human immunodeficiency virus (HIV) in the world, the lack of reliable means of prevention and treatment makes it possible to classify this problem as one of the most acute. Until 1996, Russia was among the countries with a low level of HIV infection. Since 1996, the incidence of this infection began to rise sharply. The sharp increase is mainly due to the infection of people who use drugs. The safety and quality of food products and food raw materials is one of the main factors determining the health of the population and the preservation of its gene pool. More than 5% of products do not meet hygienic requirements for the content of antibiotics.
2.3 Causes of infectious diseases and their features.
No matter how significant the achievements of modern medicine in the study of various infectious diseases are, in our time there are a number of potentially dangerous infections that can cause significant harm to the human body, and by and large, are deadly for it. To date, doctors are aware of about 1200 different infections, more or less dangerous, since not all of them have been studied to the end and not all of them have a means of salvation. There are such infectious diseases, the causes of which are not entirely clear, and the treatment is complicated by the fact that the cures for the disease have not yet been created.
A characteristic feature of all infectious diseases is the incubation period - the period between the time of infection and the manifestation of the first signs. Depending on what type of pathogen took place, as well as on how the infection occurred, the duration of the incubation period may be different. From the moment of infection to the first symptoms, it can take several hours and even, in rare cases, several years.
Pathogenic microorganisms can enter the body in different ways, and each species may have its own ways. Transmission mechanisms can also differ in different types of infections, and the ability of the pathogen to exist in the external environment outside the infected organism plays an important role here. Just during the period when pathogenic organisms are in the external environment, they are most vulnerable, many of them die from drying, sunlight, etc. At the same time, being outside the source of infection, infectious agents pose a danger to healthy people, especially since many of them microorganisms retain the ability to survive in a favorable environment for them for a long time.
2.4 Ways of transmission of infection.
Infectious diseases can be transmitted in different ways, the causes of a disease in a person can be different, the treatment of an infection involves the mandatory search for the source of infection, ascertaining the circumstances of the onset of the disease, in order to prevent its further spread.
1. Transmission of infection through the outer cover. In this case, the causative agent of the infection is transmitted by touching the patient with a healthy person. Contact can be direct and indirect (through household items).
2. Fecal-oralmode of transmission: the pathogen is excreted along with the feces of an infected person, and transmission to a healthy person occurs through the mouth.
3. Water mechanismtransmission occurs through dirty water.
4. Air wayoccurs in infections, mainly of the respiratory tract. Some pathogens are transmitted with droplets of mucus, other microbes enter the body with dust particles.
5. Among other things, infectious agents can be transmitted by insects, sometimes this transmission mechanism is called transmissible .
2. 5 Nosogeography of infectious diseases.
The geography of diseases is largely determined by the influence of natural (climate, the presence or absence of some chemical elements in water, soil, and, consequently, in food products, etc.) and social (material living conditions, cultural level of the population, traditional type of food, etc.). e) factors. This geography is called nosogeography. It is closely related to epidemiological geography (i.e., the geography of infectious diseases), microbiology, hygiene, pathology, etc.
It has long been noted that many human diseases are found only in certain parts of the globe: for example, yellow fever - in the countries of South America and Africa, cholera - most often in India and adjacent Asian countries, leishmaniasis - mainly in arid countries, etc. And in the conditions of the former USSR, many diseases had a fairly clear regional character. So, Ufa was "recognizable" by cholecystitis, in Tagil and Taganrog diseases of the upper respiratory tract were more common; Kineshma was characterized by chronic pyelonephritis; in Salavat suffered from chronic and rheumatic heart diseases; in large cities there are more gastrointestinal diseases; in port cities - venereal, etc. Not only cities, but also entire regions of the former Soviet Union were "recognizable" by characteristic diseases. In the Far North, vitamin deficiencies are common; The Far East is dangerous with tick-borne encephalitis; in Ukraine and Belarus increased incidence of bronchial asthma; in Dagestan, iron deficiency anemia was most often recorded; in Karelia, Kazakhstan, Buryatia, Astrakhan and Murmansk regions, esophageal cancer predominates, etc.
2.6 Classification of infectious diseases.
Intestinal infections
- infections of the skin and mucous membranes
- respiratory infections
- blood infections.
In each group there is an individual mode of transmission of infection and its own ways of transmitting microorganisms.
The causative agent of intestinal infections (dysentery, cholera, typhoid fever, infectious hepatitis, botulism) is released into the environment with feces, vomit. The causative agent of intestinal infections enters the organisms of healthy people with contaminated water and food, with unwashed hands or with the help of flies.
The causative agent of respiratory tract infections (whooping cough, diphtheria, measles, SARS) is released into the external environment when coughing, when sputum is discharged, when sneezing, and simply with exhaled air. In the organisms of healthy people, the infection enters with contaminated air and dust.
Influenza is the most common infectious disease. It is caused by different strains of the influenza virus, and since there is a different strain almost every year, no effective vaccine can be developed. The source of infection is a sick person. The route of transmission is airborne. From the moment of infection to the onset of symptoms of the disease, 1-3 days pass.
Influenza is manifested by fever or fever with chills, headache, feeling of general weakness, often joint and muscle pain. In parallel, and even somewhat earlier, there is a characteristic feeling of sore throat, dry cough, accompanied by pain in the trachea. This is usually accompanied by burning and redness of the conjunctiva of the eyes; most patients have a runny nose.
The diagnosis of influenza is quite simple. The number of diseases in Poland is gradually increasing. The annual number of cases in Poland ranges from 1.5 to 6 million people.
The flu is often taken lightly, and this is wrong. Influenza can be very dangerous for people with pre-existing other illnesses or those who take medication regularly, as well as for the elderly. The most common complication is pneumonia. Young children and the elderly should be monitored by a doctor if they have the flu.
The causative agent of blood infections (leishmaniasis, phlebotomic fever, malaria, encephalitis (tick-borne and mosquito), plague, fever, typhoid) lives in the blood of arthropods. A healthy person becomes infected with the bites of arthropods: ticks, mosquitoes, horseflies, fleas, lice, flies, midges and midges.
The causative agent of infections of the skin and mucous membranes
(venereal diseases, anthrax, erysipelas, scabies, trachoma) enters the body of a healthy person through wounds and other skin lesions. And also through the mucous membranes. A healthy person becomes infected with these infections through sexual contact with sick people, household contacts (using towels and bedding, linen), saliva and bites from infected animals, abrasions and scratches, and contact with damaged areas of the skin of contaminated soil.
If an infectious disease is detected, the patient must be immediately isolated. It is necessary to identify all people who were in contact with the patient and, if possible, isolate them during the incubation period of the disease. Such measures are being taken in order to prevent an epidemic of a dangerous infection.
Because In our city, a large number of hepatitis A diseases have been identified, I consider it necessary to give a more detailed description of this disease and talk about its prevention.
Viral hepatitis A is a human infectious disease characterized by a predominant lesion of the liver, in typical cases it is manifested by general malaise, fatigue, anorexia, nausea, vomiting, and sometimes jaundice (dark urine, discolored stools, yellowing of the sclera and skin). The incubation period ranges from 7 to 50 days, more often 25 to 30 days. Transmission factors are water, food products (usually not subjected to heat treatment) and household items. The source of infection is a sick person. The way of infection with this disease is the same as with intestinal infections. It should be noted that two circumstances contribute to the wide spread of hepatitis A.
Firstly, Hepatitis A virus is much more resistant to sunlight, disinfectants and boiling than pathogens of other intestinal infections, so it can persist in the external environment for a long time.
Secondly, the most dangerous for those around the patient before the appearance of jaundice. During this period, he releases the greatest number of viruses, although either dyspeptic symptoms or flu-like phenomena come to the fore: fever, headache, lethargy, runny nose, cough. Patients with anicteric and asymptomatic formspose the greatest danger to others. Thus, an outwardly healthy person can serve as a source of danger to others. The highest concentration of the pathogen in the feces of the source of infection is observed in the last 7-10 days of the incubation period and in the first days of the disease.
Prevention of hepatitis A:
1. Compliance with the rules of personal hygiene.
2. Control over the quality of drinking water and food.
3. Immunoprophylaxis of hepatitis A includes the introduction of a vaccine or immunoglobulin.
No less acute problem of our city remains the infectious disease AIDS.acquired immunodeficiency syndrome.
In 1981, a new unknown disease was reported in the United States, which often ended in death. As a result of the research, it was found that this disease is of a viral nature, it was called the Immunodeficiency Syndrome (AIDS). The virus that causes the disease is called HIV (Human Immunodeficiency Virus). This virus infects those cells of the human body that are designed to counteract the viral system, this virus penetrates into lymphocytes - blood cells. On the screen you see -Healthy lymphocyte cell”.
The HIV virus enters the lymphocytes - blood cells that provide immune protection of the human body, multiply in them and cause their death.New viruses infect new cells , but before the number of lymphocytes decreases to such an extent that immunodeficiency develops, it may take years (usually 4-6 years), during which the virus carrier is a source of infection for other people.The lack of immune protection in a sick person leads to greater susceptibility to various infections.
Symptoms of the development of the disease:
secondary infections of a bacterial, fungal, viral nature (there is an increase in the lymph glands, pneumonia, prolonged diarrhea, fever, weight loss)
cancer diseases
damage to the central nervous system (weakening of memory, intelligence, impaired coordination of movements).
Ways of HIV transmission
through blood and blood products,
from mother to newborn child.
AIDS prevention
use of disposable syringes and needles.
use personal hygiene items.
disinfection of manicure tools.
avoid acupuncture treatment outside medical facilities,
Avoid tattoos and ear piercings with non-sterile instruments.
III . Conclusion. Prevention of infectious diseases.
Infectious diseases are natural phenomena in the history of mankind, which are formed and reborn along with it. Some infections replace others, and with them new problems come. prevention . To date, the incidence of infectious diseases remains very high, and the prevalence covers the whole world. Tens of millions of infectious diseases are registered every year.
Modern drugs provide treatment for the patient, taking into account his individual characteristics and the specifics of the course of the disease. Proper care of the patient and rational nutrition are of great importance. To avoid infection, you must observe and applypreventive measures .
prevention of intestinal infectious diseases , when this infection is detected, isolation and treatment of patients is carried out. Observe the rules for storage, preparation and transportation of food. Wash your hands with soap and water before eating and after going to the toilet. Thoroughly wash vegetables and fruits, boil milk and drink only boiled water.
prevention of blood infections , when this infection is detected, the sick are isolated, they are monitored
prevention of infectious diseases of the external integument , when this infection is detected, the patient is isolated and treated. The hygiene regime must be strictly observed. For prevention purposes, preventive vaccinations are used.
Today, there are a number of infections that only vaccination can help protect against. Why is vaccination necessary? Vaccinationimmunoprophylaxis of infectious diseases , creates active immunity to infections. Re-vaccination should be done to maintain reliable immunity. Prevention of childhood infectious diseases is carried out primarily with weakened and often ill children, as they are more at risk of contracting infectious diseases that occur in their severe form.
Before you do a preventive vaccination, you need to look around at the therapist or pediatrician, and make sure that there are no contraindications. Having been vaccinated will ensure that you do not catch any infection.
How to prevent an infectious disease?
Everyone should know that if signs of an infectious disease are detected, an urgent need to seek medical help. In no case should you hide it, an outbreak of an infectious disease can harm both relatives and the whole team at work. When the patient is isolated, he will cease to be a source of infection in the team. The most reliable way to protect yourself from an infectious disease is toprevention of infectious diseases , which is timely immunization. It is necessary to increase the characteristic resistance of the organism to various pathogens, that is, to influence the immune system. In order to prevent some infectious diseases, prophylactic use of chemotherapy drugs and antibiotics is carried out.
About the prevention of SARS and influenza
High fever, chills and headache are indispensable companions of SARS and influenza. But even in the most dangerous period, colds can be avoided. To prevent a cold infection from overpowering you and your children, follow simple preventive measures.
One of the most common and affordable means of preventing influenza is a mask. It should be worn by both the sick person and those who are in contact with him.
Remember that the infection is easily transmitted through dirty hands, so for the period of epidemics it is better to refuse handshakes. Hands should also be washed frequently, especially when sick or caring for the sick.
During the epidemic, it is recommended to avoid traveling by public transport and not to visit.
You can take ascorbic acid and multivitamins. Vitamin C is used orally at 0.5-1 g 1-2 times a day. A large amount of vitamin C is also found in sauerkraut juice, as well as in kiwi and citrus fruits - lemons, tangerines, oranges, grapefruits.
For prevention during epidemics of influenza and colds, you need to eat garlic, 2-3 cloves daily. It is enough to chew a clove of garlic for several minutes to completely cleanse the oral cavity of bacteria. Onions also have a positive effect.
The daily presence of fresh vegetables and fruits in the diet will increase overall immunity.
Do not forget about the toilet of the nose - wash the anterior sections of the nose with soap 2 times a day. At the same time, foreign structures that have entered the nasal cavity with inhaled air are mechanically removed.
Overcooled? Take a warm mustard foot bath (5-10 minutes) and put on wool socks.
You need to walk as much as possible. It is almost impossible to get SARS and flu in the fresh air!
At the first symptoms of the disease, stay at home and call a medical worker!!!
Suspension of the educational process in schools in Saratov allowed to reduce the incidence of acute respiratory viral infections and influenza among schoolchildren by 25%, but the incidence rate among children aged 7-14 years remains above the estimated epidemic threshold by 91.9%. In this regard, it was decided to extend the extraordinary holidays for schoolchildren until February 23, 2013.
Theoretical and practical significance of the work performed.
I recommend using this work in class hours in order to prevent infectious diseases, in biology lessons when studying the topic "Immunity". Since an outbreak of Hepatitis A was detected on the territory of the BIS, cases of HIV-infected people were detected, and epidemics of acute respiratory viral infections and influenza were registered, I gave a description of these diseases and their prevention.
Our health is in our hands!
Topic: INFECTIOUS DISEASES AND THEIR PREVENTION
infectious process.
epidemic process.
Federal Law "On Immunoprophylaxis of Infectious Diseases".
The concept of immunity and its types.
General principles for the prevention of infectious diseases.
INFECTIOUS PROCESS
Infectious diseases include those that develop as a response of the body to the introduction and reproduction of pathogens. A characteristic and distinctive feature of an infectious disease is the ability of the pathogen to spread in the environment of the sick person and cause new cases of diseases. Therefore, infectious diseases are called contagious.
The nature of an infectious disease is the infectious process is the result of the confrontation between the patient's body and the invading microorganisms. During the development of the infectious process, there are violations of the structure and function of the affected organs and systems of the body, which leads to disorders in the normal functioning of a person. The nature of the development of the infectious process, the characteristics of the course of the disease and the outcome of the disease are determined by the following factors:
1. Pathogenic properties (pathogenicity) of the pathogen: a) its virulence (the ability to penetrate the protective barriers of the human body); b) its reproduction (the ability to multiply intensively in the tissues of an infected organism); c) its toxigenicity (the ability to release bacterial poisons or toxins).
2. The protective potential of the human body or its susceptibility to an infectious onset, which depends on: a) resistance or immunity to infection as a result of innate or acquired immunity; b) reactivity, the state of the body's defense system.
3. Habitat conditions, determining the possibility of interaction between macro- and microorganism. Pathogens that can cause an infectious process are called pathogenic, and this property is called pathogenicity. The degree of pathogenicity of a particular pathogen is estimated as virulence. They talk about high or low virulence of pathogenic microbes. The causative agents of infectious diseases are bacteria, viruses, rickettsia (typhus), microscopic fungi, and protozoa.
To indicate the state of infection of the body with protozoa, the term " invasion"(from lat. Invasion - invasion, invasion).
entrance gate causative agent (the place of penetration of the infectious principle into the human body):
Leather,
- mucous membranes,
Tonsils.
infectious dose. For a person to fall ill, that is, for an infectious process to occur, an appropriate infectious dose is needed, which is different for different pathogens and different for each person. For example, the minimum doses for tularemia are 15 live sticks, anthrax - 6000, dysentery - 500 million microbial cells. .
The specificity of the infectious process. The infectious process is always specific, that is, it depends on the type of pathogen. Vibrio cholerae can only lead to the development of cholera, the influenza virus causes influenza, the dysentery bacillus causes dysentery, the measles virus causes measles, etc.
In the process of dynamic development of almost any infectious disease, characteristic periods:
1. Incubation or latent (hidden) period of the disease, which lasts from the moment of infection until the first signs of the disease appear (flu - from several hours to 3 days, AIDS - years);
2. Prodromal period of the disease (harbingers). During this period, symptoms common to all diseases predominate: general malaise, fever, headache, general weakness, and a state of discomfort. At the end of the prodromal period, in some infectious diseases, specific symptoms appear (rash with bark or scarlet fever);
3. Clinical period of the disease (height of the disease), when the symptoms of the disease are most fully deployed, and the specific signs of the disease appear most clearly ; the apogee of the infectious process;
4. The outcome of an infectious disease: a) recovery, b) death, c) chronic form, d) recovery with residual effects of the disease or its complications, e) bacteriocarrier.
Forms of the course of the infectious process. According to the severity of the course, infectious diseases are divided into 1) acute: flu, measles, scarlet fever, chickenpox, etc.; 2) chronic: malaria, tuberculosis, etc. Many infections have acute and chronic forms: dysentery, brucellosis, etc. There are also latent (hidden) current , when the pathogen, multiplying, is in the body for a long time and does not cause clinical symptoms of the disease. Sometimes this form of the disease is called an asymptomatic infection.
Bacteriocarrier- a special form of relationship between a microorganism and a person. It is most often observed in the period after recovery from infection. It is characteristic that there is a microbe in the body, but there are no signs of the disease. A healthy bacteriocarrier is when no signs of the disease develop at all, despite the introduction of a pathogen.
mixed infection- this is an infection with several pathogens (measles and scarlet fever, dysentery and typhoid fever).
secondary infection- this is when, for example, after a viral infection (influenza), inflammation of the lungs caused by the bacterial flora develops.
Focal infection- for example, a furuncle, a syphilitic ulcer, tuberculosis can be localized. If the infection spreads throughout the body, they talk about process generalization(for example, sepsis occurs from a boil).
Superinfection - re-infection with the same pathogen, when the disease has not yet ended. For example, without recovering from the flu, the patient may receive an additional “portion” of viruses from another source of infection. The course of the disease worsens.
reinfection- re-infection with the same type of microbe, but after complete recovery from the previous infection. The course of the disease is easier, as there is immunity.
relapse- this is a return of the disease, an exacerbation in its chronic course.
Remission- a period of relative well-being in the chronic course of the disease between relapses.
Each of the forms of the infectious process has its own clinical and epidemiological significance. For example, latent (hidden) infection and healthy bacterial carriage are of extremely important epidemiological significance, since in these cases, patients usually do not seek treatment and serve as an active source of infection for healthy people for a long time. A person who has had an infectious disease during the recovery period is called convalescent.
Causes of exacerbations and relapses of the disease:
Violation of the regimen or diet prescribed by the doctor;
Activation of the pathogen that caused the underlying disease (reinfection) due to a decrease in the body's resistance;
New infection with another type of pathogen of this disease (superinfection) when communicating with people infected with this infectious disease;
Layering of extraneous microbial flora (secondary infection) due to violation of hygiene requirements when caring for patients;
Insufficient tension of the formed immunity after a previous infection.
Both the course of the infectious process and the severity of the main manifestations of the disease are influenced by forms of spread of the pathogen in the body:
1. Bacteremia and viremia- the process of spreading the pathogen with blood flow through organs and tissues, or generalization of infection. This process can lead to sepsis;
2. Septicemia (sepsis)- filling with microbes of many organs and tissues (anthrax, pyogenic cocci). Sepsis is characterized by the same clinical picture with different microbes. The septic component during an infectious disease can significantly aggravate the course and prognosis, for example, of salmonella, staphylococcal and meningococcal infections.
3. Septicopyemia- this is sepsis, leading to the formation of purulent foci in various organs and tissues.
4. Toxinemia leads to poisoning of the body with toxins that the pathogen produces, and the development of symptoms of intoxication. Clinical signs of intoxication are caused by toxic damage to the central nervous system (headache, dizziness, nausea, vomiting, convulsions, loss of consciousness, etc.), respiratory system (shortness of breath, suffocation, respiratory arrest), blood circulation (tachycardia, bradycardia, increase or decrease in blood pressure , collapse), discharge (polyuria, anuria, dyspepsia, etc.). The toxic component determines the severity of tetanus, botulism, influenza, diphtheria and other infectious diseases.
The macroorganism has a whole series of protective mechanisms against the effects of harmful agents, which are united by a common term - reactivity and as a consequence - resistance, which is stability.
resistance plays a decisive role in the occurrence, course and outcome of an infectious disease. Resistance decreases from starvation, lack of vitamins, physical and mental overwork, cooling, etc., and increases as a result of the elimination of harmful labor factors, the organization of rest and life, hereditary and acquired immunity.
Thus, the occurrence of an infectious process and the form of its course in each specific case are determined by the result of the confrontation between the pathogenic agent and the human body. The outcomes of this confrontation can be: a) the death of the pathogen, b) the emergence of an infectious process (disease); c) mutual adaptation ("healthy bacteria carrier").
EPIDEMIC PROCESS
1. The source of infection that releases the pathogen into the environment (human, animals),
2. Factors of transmission of the pathogen,
3. A susceptible organism, that is, a person who does not have immunity against this infection.
Sources of infection:
1 person. Infectious diseases that affect only people are called anthroponoses (from the Greek anthropos - a person, noses - a disease). For example, only people get sick with typhoid fever, measles, whooping cough, dysentery, cholera.
2. Animals. A large group of human infectious and parasitic diseases are zoonoses (from the Greek zoos - animals), in which various types of domestic and wild animals and birds serve as the source of infection. Zoonoses include brucellosis, anthrax, glanders, foot and mouth disease, etc.
There is also a group of zooatroponous infections, in which both animals and people can serve as a source of infection (plague, tuberculosis, salmonellosis).
Transmission factors. Pathogens are transmitted to healthy people by one or more of the following routes:
1. Air- influenza, measles are transmitted only through the air, for other infections, air is the main factor (diphtheria, scarlet fever), and for others - a possible factor in the transmission of the pathogen (plague, tularemia);
2. Water - typhoid fever, dysentery, cholera, tularemia, brucellosis, glanders, anthrax, etc.;
3. Soil- anaerobes (tetanus, botulism, gas gangrene), anthrax, intestinal infections, worms, etc.;
4. Food products- all intestinal infections. With food, pathogens of diphtheria, scarlet fever, tularemia, plague, etc. can also be transmitted;
5. Items of labor and household items, infected with a sick animal or person, can serve as a factor in the transmission of an infectious beginning to healthy people;
6. Arthropods- are often carriers of pathogens of infectious diseases. Ticks transmit viruses, bacteria and rickettsiae; lice - typhus and relapsing fever; fleas - plague and rat typhus; flies - intestinal infections and worms; mosquitoes - malaria; ticks - encephalitis; midges - tularemia; mosquitoes - leishmaniasis, etc.;
7. Biological fluids ( blood, nasopharyngeal secretions, feces, urine, semen, amniotic fluid) - AIDS, syphilis, hepatitis, intestinal infections, etc.
The main epidemiological characteristics of the emergence and spread of an infectious disease are determined by the speed of spread, the vastness of the territory of the epidemic and the mass coverage of the disease in the population.
Options for the development of the epidemic process:
1. sporadia(sporadic incidence). There are single, unrelated cases of infectious diseases that do not take a noticeable spread among the population. The property of an infectious disease to spread in the environment of the sick person is expressed in a minimal way (for example, Botkin's disease).
2. Endemic- group flash. It occurs, as a rule, in an organized team, in conditions of constant and close communication between people. The disease develops from one, common source of infection and in a short time covers up to 10 or more people (an outbreak of mumps in a kindergarten group).
3. Epidemic outbreak. The mass spread of an infectious disease that occurs from a series of group outbreaks and covers one or more organized groups with a total number of 100 or more sick people (intestinal infections and food poisoning).
4. Epidemic. Mass morbidity of the population, in a short time spreading over a vast territory, covering the city, district, region and a number of regions of the state. An epidemic develops from many epidemic outbreaks. The number of cases is estimated at tens and hundreds of thousands of people (epidemics of influenza, cholera, plague).
5. Pandemic. Global spread of epidemic morbidity among humans. The epidemic covers vast territories of various states on many continents of the globe (pandemics of influenza, HIV infection).
Natural focality of infectious diseases- the spread of the disease within certain territorial zones.
Such a phenomenon, when a disease is recorded with great constancy in a certain area, is called endemic. Typically, this is zoonotic infections that spread in the respective territorial foci among animals, with the help of insects that carry the infectious agent. The doctrine of the natural foci of infectious diseases was formulated in 1939 by Academician E.N. Pavlovsky. Natural foci of infectious diseases are called nosoareals, and infectious diseases characteristic of territories are called natural focal infections (hemorrhagic fevers, tick-borne encephalitis, plague, tularemia, etc.).
They can be called environmentally conditioned diseases, since the cause of endemicity is natural factors that favor the spread of these diseases: the presence of animals - sources of infection and blood-sucking insects that act as carriers of the corresponding infection. The nosoareal of cholera is India and Pakistan. A person is not a factor that can support the existence of a focus of natural infection, since such foci formed long before the appearance of people in these territories. Such foci continue to exist after the departure of people (upon completion of exploration, road and other temporary work). The undoubted priority in the discovery and study of the phenomenon of natural foci of infectious diseases belongs to domestic scientists - Academician E.N. Pavlovsky and Academician A.A. Smorodintsev.
Epidemic focus. The object or territory where the epidemic process unfolds is called the epidemic focus. The epidemic focus may be limited to the apartment where the sick person lives, may cover the territory of a preschool institution, school, university, include the territory of a settlement, region. The number of cases in the focus can vary from one or two to many hundreds and thousands of cases.
Elements of an epidemic focus:
1. Sick people and healthy bacteria carriers are sources of infection for people around them;
2. Persons who have been in contact with sick people (“contacts”), who, if they develop a disease, become a source of infection;
3. Healthy people who, by the nature of their work, represent a group with an increased risk of spreading the infection - the “declared group of the population” (employees of public catering establishments, water supply, medical workers, teachers, etc.);
4. The room in which there is or was a sick person, including the furnishings and everyday items in it that contribute to the transmission of an infectious principle to susceptible people;
5. Environmental factors, especially in rural areas, that can contribute to the spread of infection (sources of water use and food supply, the presence of rodents and insects, places for collecting waste and sewage);
6. Healthy population on the territory of the focus, who had no contact with patients and bacteria carriers, as a contingent susceptible to infection, not immune from possible infection in an epidemic focus.
All of the listed elements of the epidemic focus reflect the three main links of the epidemic process: the source of infection - the route of transmission (mechanism of infection) - the susceptible contingent.
Appropriate anti-epidemic measures should be directed to all elements of the epidemic focus in order to most quickly and effectively solve two interrelated tasks: 1) strictly localize the focus within its boundaries,
to prevent the "spreading" of the boundaries of the focus; 2) to ensure the speedy elimination of the focus itself in order to prevent a mass disease of the population.
Mechanism of transmission consists of 3 phases:
2) the presence of the pathogen in the external environment,
3) the introduction of the pathogen into a new organism.
With air mechanism infection can be transmitted as by airborne droplets, so air-dust. The causative agents of infectious diseases are released into the air from the nasopharynx of a sick person when breathing, when talking, but especially intensively when sneezing and coughing, spreading with droplets of saliva and nasopharyngeal mucus several meters from a sick person. Thus, acute respiratory viral infections (ARVI), whooping cough, diphtheria, mumps, scarlet fever, etc. are spreading. Air dust path the spread of infection, when pathogens with air currents are able to spread over considerable distances from a sick person, is characteristic of “volatile” viral infections (chickenpox, measles, rubella, etc.). With the airborne route of infection, the pathogen enters the body, mainly through the mucous membranes of the upper respiratory tract (through the respiratory tract), then spreading throughout the body.
Fecal-oral mechanism Infection is characterized by the fact that in this case the causative agents of the infection, being released from the body of a sick person or a bacteriocarrier with its intestinal contents, enter the environment. Then, through contaminated water, food, soil, dirty hands, household items, the pathogen enters the body of a healthy person through the gastrointestinal tract (dysentery, cholera, salmonellosis, etc.).
blood mechanism infection differs in that the main factor in the spread of infection in such cases is infected blood, which penetrates into the bloodstream of a healthy person in various ways. Infection can occur during blood transfusion, as a result of unskilled use of reusable medical instruments, in utero from a pregnant woman to her fetus (HIV infection, viral hepatitis, syphilis). This group of diseases includes transmissive infections spread through the bites of blood-sucking insects (malaria, tick-borne encephalitis, tick-borne boreliosis, plague, tularemia, hemorrhagic fevers, etc.).
contact mechanism infection can be carried out both by direct and indirect (indirect) contact - through infected everyday items (various skin diseases and sexually transmitted diseases - STDs).
Some infectious diseases are characterized by pronounced seasonality (intestinal infections during the hot season).
A number of infectious diseases are age-specific, for example, childhood infections (whooping cough).
The main directions of anti-epidemic measures
As mentioned, the epidemic process arises and is maintained only in the presence of three links: the source of infection, the mechanism of transmission of the pathogen, and the susceptible population. Consequently, the elimination of one of the links will inevitably lead to the termination of the epidemic process.
The main anti-epidemic measures include:
1. Measures aimed at eliminating the source of infection: identification of patients, bacteria carriers, their isolation and treatment; detection of persons who have been in contact with the sick, for subsequent monitoring of their health, in order to timely identify new cases of diseases and isolate sick people in a timely manner.
2. Measures aimed at preventing the spread of infection and to prevent the expansion of the boundaries of the outbreak:
a) regime restrictive measures- observation and quarantine. Observation- specially organized medical monitoring of the population in the focus of infection, including a number of measures aimed at the timely detection and isolation of patients in order to prevent the spread of the epidemic. At the same time, with the help of antibiotics, they carry out emergency prophylaxis, make the necessary vaccinations, monitor the strict implementation of the rules of personal and public hygiene. The period of observation is determined by the duration of the maximum incubation period for a given disease and is calculated from the moment of isolation of the last patient and the end of disinfection in the outbreak. Quarantine- this is a system of the most stringent isolation and restrictive anti-epidemic measures taken to prevent the spread of infectious diseases;
b) disinfection measures, including not only disinfection, but also disinsection, deratization (destruction of insects and rodents);
3. Measures aimed at increasing the resistance of the population to infection, among which the most important are the methods of emergency prevention of the onset of the disease:
a) population immunization according to epidemic indications;
b) preventive use of antimicrobials(bacteriophages, interferons, antibiotics).
These anti-epidemic measures in the conditions of an epidemic focus are necessarily supplemented by a number of organizational measures aimed at limiting contacts among the population. In organized groups, sanitary-educational and educational work is carried out, the media are involved. The educational and sanitary-educational work of teachers with students is of great importance.
Disinfection methods in an epidemic outbreak. Disinfection is a set of measures aimed at destroying pathogens and eliminating sources of infection, as well as preventing further spread. Disinfection measures include:
1) disinfection(methods for the destruction of pathogens),
2) pest control(methods of destruction of insects - carriers of pathogens of infectious diseases),
3) deratization(methods of destruction of rodents - sources and spreaders of infection).
In addition to disinfection, there are other ways to destroy microorganisms: 1) sterilization(boiling instruments for 45 minutes prevents infection with epidemic hepatitis), 2) pasteurization- heating liquids to 50-60 degrees in order to disinfect them (for example, milk). Within 15-30 minutes, the vegetative forms of Escherichia coli die.
Disinfection methods. Physical and chemical disinfection methods are used for disinfection. To physical methods include boiling, autoclaving, heat treatment in dry ovens, in disinfection chambers, ultraviolet irradiation. Chemical Methods disinfection is carried out using chemicals with high bactericidal activity (chlorine, chloramine, calcium and sodium hypochlorites, lysol, formalin, carbolic acid). Soaps and synthetic detergents also have a disinfecting effect. biological methods disinfection is the destruction of microorganisms by means of a biological nature (for example, with the help of antagonist microbes). It is used for disinfection of sewage, garbage and garbage.
For focal current and final disinfection in foci of intestinal infections, a 0.5% solution of chlorine-containing disinfectants is used, with airborne infections - 1.0%, in foci of active tuberculosis - 5.0%. When working with disinfectants, care must be taken (use protective clothing, goggles, mask, gloves).
FEDERAL LAW "ON IMMUNOPROPHYLAXIS OF INFECTIOUS DISEASES" dated September 17, 1998 No. 157-FZ.
Immunoprophylaxis of infectious diseases- a system of measures taken to prevent, limit the spread and eliminate infectious diseases through preventive vaccinations.
Preventive vaccinations- the introduction of medical immunobiological preparations into the human body to create specific immunity to infectious diseases.
Medical immunobiological preparations- vaccines, toxoids, immunoglobulins and other drugs designed to create specific immunity to infectious diseases.
- a normative act establishing the terms and procedure for carrying out preventive vaccinations for citizens.
Post-vaccination complications caused by preventive vaccinations included in the national calendar of preventive vaccinations, and preventive vaccinations according to epidemic indications - severe and persistent health disorders due to preventive vaccinations.
Certificate of preventive vaccinations- a document in which preventive vaccinations of citizens are registered.
State policy in the field of immunoprophylaxis(extracts from article 4).
1. The state policy in the field of immunoprophylaxis is aimed at preventing, limiting the spread and eliminating infectious diseases.
In the field of immunoprophylaxis, the state guarantees:
availability of preventive vaccinations for citizens;
free carrying out of preventive vaccinations included in the National calendar of preventive vaccinations, and preventive vaccinations according to epidemic indications in organizations of the state and municipal health systems;
social protection of citizens in the event of post-vaccination complications;
use for the implementation of immunoprophylaxis of effective medical immunobiological preparations.
1. Citizens in the implementation of immunoprophylaxis have the right to:
obtaining complete and objective information from medical workers about the need for preventive vaccinations, the consequences of refusing them, and possible post-vaccination complications;
choice of state, municipal or private healthcare organizations or citizens engaged in private practice;
free preventive vaccinations included in the National calendar of preventive vaccinations, and preventive vaccinations according to epidemic indications in organizations of the state and municipal health systems;
free medical examination, and if necessary, a medical examination before preventive vaccinations in state and municipal healthcare organizations;
free treatment in state and municipal healthcare organizations in case of post-vaccination complications;
social protection in the event of post-vaccination complications;
refusal of preventive vaccinations.
prohibition for citizens to travel to countries where stay in accordance with international health regulations or international treaties of the Russian Federation requires specific preventive vaccinations;
temporary refusal to admit citizens to educational and health-improving institutions in the event of mass infectious diseases or the threat of epidemics;
refusal to hire citizens for work or suspension from work, the performance of which is associated with a high risk of contracting infectious diseases.
comply with the instructions of medical workers;
confirm in writing the refusal of preventive vaccinations.
These preventive vaccinations are carried out for all citizens of the Russian Federation within the time limits established by the National Calendar of Preventive Immunizations. (Extract from article 9).
Immunization calendar(Compiled in accordance with the order of the Ministry of Health of the Russian Federation dated December 18, 1997 No. 375 “On the vaccination calendar”
CONCEPT ABOUT IMMUNITY AND ITS TYPES
Organs of the immune system:
· central: bone marrow and thymus (thymus gland);
· peripheral: accumulations of lymphoid tissue in the intestines, lungs, genitourinary system (tonsils, Peyer's patches), lymph nodes, spleen. Peripheral organs of the immune system, like watchtowers, are located on the path of possible advancement of genetically alien substances.
Protection factors are divided into non-specific and specific.
Nonspecific mechanisms of immunity These are general factors and protective adaptations of the body. These include: impermeability of healthy skin and mucous membranes;
impermeability of histo-hematological barriers; the presence of bactericidal substances in biological fluids (saliva, tears, blood, cerebrospinal fluid); excretion of viruses by the kidneys; phagocytic system; barrier function of lymphoid tissue; hydrolytic enzymes; interferons; lymphokines; complement system, etc.
Intact skin and mucous membranes of the eyes, respiratory tract, gastrointestinal tract, and genital organs are impervious to most microbes. The secrets of the sebaceous and sweat glands have a bactericidal effect against many infections (except for pyogenic cocci).
Peeling of the skin - the constant renewal of the upper layer - is an important mechanism for its self-purification from microbes and other contaminants. Saliva contains lysozyme, which has an antimicrobial effect. The blinking reflex of the eyes, the movement of the cilia of the epithelium of the respiratory tract in combination with the cough reflex, intestinal motility - all this contributes to the removal of microbes and toxins. Thus, intact skin and mucous membranes are first protective barrier for microorganisms.
If an infection breakthrough occurs (trauma, burns, frostbite), then the next line of defense comes out - second barrier - an inflammatory reaction at the site of the introduction of microorganisms.
The leading role in this process belongs to phagocytosis (factors of cellular immunity). Phagocytosis, first studied by I.I. Mechnikov, is the absorption and enzymatic digestion by macro- and microphages - cells of mesodermal origin - microbes or other particles, resulting in the release of the body from harmful foreign substances. Reticular and endothelial cells of lymph nodes, spleen, bone marrow, Kupffer cells of the liver, histiocytes, monocytes, polyblasts, neutrophils, eosinophils, basophils have phagocytic activity.
Each of these factors and adaptations is directed against all microbes. Nonspecific protective factors neutralize even those substances that the body has not encountered before. The body's defense system is very vulnerable. The main factors that reduce the body's defenses include: alcoholism, smoking, drugs, psycho-emotional stress, physical inactivity, lack of sleep, overweight. A person's susceptibility to infection depends on his individual biological characteristics, on the influence of heredity, on the characteristics of the human constitution, on the state of his metabolism, on the neuroendocrine regulation of life support functions and their functional reserves; on the nature of nutrition, vitamin supply of the body, on climatic factors and the season of the year, on environmental pollution, the conditions of his life and activity, on the lifestyle that a person leads.
Specific mechanisms of immunity- this is antibody formation in the lymph nodes, spleen, liver and bone marrow. Specific antibodies are produced by the body in response to an artificial introduction of an antigen (vaccination) or as a result of a natural encounter with a microorganism (infectious disease).
Antigens- substances that carry a sign of foreignness (proteins, bacteria, toxins, viruses, cellular elements). These substances are able to: a) cause the formation of antibodies, b) interact with them.
Antibodies- proteins that can bind to antigens and neutralize them. They are strictly specific, that is, they act only against those microorganisms or toxins, in response to the introduction of which they have been developed. Among the antibodies, there are: antitoxins (neutralize microbial toxins), agglutinins (stick together microbial cells), precipitins (precipitate protein molecules), opsonins (dissolve microbial cells), virus-neutralizing antibodies, etc. All antibodies are altered globulins or immunoglobulins (Ig), protective substances, elements of humoral immunity. 80-90% of antibodies are in gamma globulins. So IgG and IgM protect against viruses and bacteria, IgA protects the mucous membranes of the digestive, respiratory, urinary and reproductive systems, IgE is involved in allergic reactions. The concentration of Ig M increases during acute inflammatory processes, Ig G - during exacerbation of chronic diseases. Humoral immunity factors include interferons and interleukins, which are secreted by a lymphocyte when a viral infection enters the body.
The human body is able to respond with antibody formation simultaneously to 30 or more antigens. This property is used to make combination vaccines.
The “antigen + antibody” reaction occurs both in the human or animal body and in a test tube if the patient’s blood serum is mixed with a suspension of the corresponding microbes or toxins. These reactions are used to diagnose many infectious diseases: the Vidal reaction in typhoid fever, etc.
Vaccines, serums. Even in ancient times, people, describing the epidemic, pointed out: "who suffered the disease was already safe, because no one fell ill twice." Long before civilization, the Indians rubbed crusts from smallpox patients into the skin of their children for prophylactic purposes. In this case, smallpox was usually mild. The scientific substantiation of this issue was first given by the English physician E. Jenner (1749 - 1823), who prepared the smallpox vaccine on calves. After the publication of his work in 1798, smallpox vaccination quickly began to spread throughout the world. In Russia, Catherine II was the first to be vaccinated against smallpox. Since 1980, compulsory vaccination against smallpox in Russia has been canceled due to the complete elimination of this disease in the country. At present, a large number of vaccines and sera are available to prevent infectious diseases by artificially creating human immunity.
Vaccines- These are preparations from microbial cells or their toxins, the use of which is called vaccination. Antibodies appear in the human body 1-2 weeks after the introduction of vaccines.
Vaccination- the main practical purpose of vaccines. Modern vaccine preparations are divided into 5 groups:
1. Live vaccines with weakened virulence (against smallpox, anthrax, rabies, tuberculosis, plague, measles, mumps, etc.). These are the most effective vaccines. They create a long (for several years) and intense immunity. The introduced weakened live pathogen multiplies in the body, which creates a sufficient amount of antigen for the production of antibodies.
2. Killed germ vaccines prepared against typhoid fever, cholera, whooping cough, poliomyelitis, etc. The duration of immunity is 6-12 months.
3. Chemical vaccines - these are preparations not from whole microbial cells, but from chemical complexes of their surface structures (against typhoid, paratyphoid A and B, tetanus).
4. Anatoxins prepared from exotoxins of the corresponding pathogens (diphtheria, tetanus, staphylococcus, gas gangrene, etc.).
5. Associated vaccines, that is, combined (for example, DTP - associated pertussis-diphtheria-tetanus vaccine).
Serums more often used for treatment (serotherapy) of infectious patients and less often for the prevention (seroprophylaxis) of infectious diseases. The earlier the serum is administered, the more effective its therapeutic and prophylactic effect. The duration of the protective action of serums is 1-2 weeks. Serums are prepared from the blood of people who have recovered from an infectious disease or by artificially infecting animals with microbes (horses, cows, donkeys). Main types:
1. Antitoxic serums neutralize the poisons of microbes (anti-diphtheria, anti-tetanus, anti-snake, etc.).
2. Antimicrobial serums inactivate bacterial cells and viruses, are used against a number of diseases, more often in the form of gamma globulins.
Gamma globulins from human blood are available against measles, poliomyelitis, infectious hepatitis, etc. These are safe preparations, since they do not contain pathogens, unnecessary ballast substances. Gamma globulins are also prepared from the blood of hyperimmunized horses against anthrax, plague, smallpox, rabies, etc. These drugs can cause allergic reactions.
Immune sera contain ready-made antibodies and act from the first minutes after administration.
Interferon occupies an intermediate position between general and specific mechanisms of immunity, since, being formed on the introduction of a virus of one type into the body, it is also active against other viruses.
specific immunity subdivided into congenital (species) and acquired .
innate immunity inherent in a person from birth, inherited from parents. Immune substances pass through the placenta from mother to fetus. A special case of innate immunity can be considered the immunity received by a newborn with mother's milk.
Acquired immunity arises (acquired) in the process of life and is divided into natural and artificial.
Natural acquired immunity occurs after the transfer of an infectious disease: after recovery, antibodies to the causative agent of this disease remain in the blood. Often, people who have been ill in childhood, for example, with measles or chicken pox, later either do not get sick with this disease at all, or fall ill again in a mild, erased form.
Artificial immunity is developed through special medical measures, and it can be active and passive.
Active artificial immunity occurs as a result of protective vaccinations, when a vaccine is introduced into the body - or weakened pathogens of a particular disease ("live" vaccine), or toxins - waste products of pathogenic microorganisms ("dead" vaccine). In response to the introduction of the vaccine, a person, as it were, falls ill with this disease, but in a very mild, almost imperceptible form. His body actively produces protective antibodies. And although active artificial immunity does not appear immediately after the introduction of the vaccine (it takes a certain time to produce antibodies), it is quite strong and lasts for many years, sometimes for life. The closer the vaccine immunopreparation is to the natural causative agent of infection, the higher its immunogenic properties and the stronger the resulting post-vaccination immunity.
Vaccination with a live vaccine, as a rule, provides complete immunity to the corresponding infection for 5-6 years, vaccination with an inactivated vaccine creates immunity for the next 2-3 years, and the introduction of a chemical vaccine and toxoid provides protection for the body for 1-1.5 years. At the same time, the more purified the vaccine is, the less likely it is to cause unwanted, adverse reactions to its introduction into the human body. As an example of active immunity, one can name vaccinations against poliomyelitis, diphtheria, whooping cough.
Passive artificial immunity occurs as a result of the introduction into the body of serum - defibrinated blood plasma that already contains antibodies to a particular disease. Serum is prepared either from the blood of people who have recovered from this disease, or, more often, from the blood of animals that are specially vaccinated with this disease and in whose blood specific antibodies are formed. Passive artificial immunity occurs almost immediately after the introduction of serum, but since the introduced antibodies are inherently foreign, i.e. possess antigenic properties, over time, the body suppresses their activity.
Therefore, passive immunity is relatively unstable. Immune serum and immunoglobulin, when introduced into the body, provide artificial passive immunity that retains a protective effect for a short time (4-6 weeks). The most characteristic example of passive immunity is anti-tetanus and anti-rabies serum. The bulk of vaccinations are carried out at preschool age. At school age, revaccination is carried out, aimed at maintaining the proper level of immunity. An immunization schedule is a rule-prescribed sequence of vaccinations with a particular vaccine, which indicates the age of the child to be immunized, prescribes the number of necessary vaccinations against a given infection, and recommends certain time intervals between vaccinations. There is a special, legally approved immunization calendar for children and adolescents (the general schedule of immunization schemes). The introduction of sera is used in cases where the likelihood of a disease is high, as well as in the early stages of the disease, to help the body cope with the disease. For example, vaccinations against influenza in case of an epidemic threat, vaccinations against tick-borne encephalitis before leaving for field practice, after a bite from a rabid animal, etc.
Vaccination reactions. In response to the introduction of the vaccine into the body, a general, local or allergic reaction (anaphylactic shock, serum sickness) may develop. The general reaction is characterized by chills, fever, general weakness, body aches, and headache. A local reaction is usually observed at the site of injection or inoculation of the immunological drug and is manifested by redness of the skin, swelling, and soreness at the site of the vaccine. Often this is accompanied by itching. Usually, vaccination reactions are mild and short-lived. Severe reactions to the vaccine, requiring hospitalization and special medical supervision, are quite rare. Allergic reactions to vaccinations are manifested by an itchy rash, swelling of the subcutaneous tissue, joint pain, temperature reaction, less often by difficulty breathing. Vaccination of persons who previously had allergic reactions is allowed only under conditions of special medical supervision.
Indications and contraindications for immunization. The main indication for planned, unscheduled and urgently carried out immunoprophylaxis of infectious diseases is the need to create immunity to infection by stimulating the production of specific immunity by the body's immune system.
Contraindications are:
1. Allergic reactions to previous vaccinations. The decision on vaccination in this case is made by the doctor, and it is carried out in an allergological hospital;
2. Other allergic reactions: respiratory allergy, food and insect allergy. Vaccinations are carried out under the supervision of an allergist;
3. Chronic diseases that occur with a violation of the vital functions of the body; respiration, circulation, liver, kidneys, central nervous and endocrine systems;
4. Any acute diseases (flu, tonsillitis, acute respiratory disease in the acute period and within 1 month after recovery).
If contraindications are identified in some children, giving rise to a withdrawal from vaccination for health reasons (medical withdrawal), the issue of the possibility of vaccination is decided by specialist doctors collectively. The rest of the children must be vaccinated, otherwise an infectious disease in a children's institution may become widespread.
GENERAL PRINCIPLES FOR THE PREVENTION OF INFECTIOUS DISEASES
Primary prevention includes the following activities: personal hygiene, hardening, preventive and ongoing sanitary supervision, promotion of knowledge about infectious diseases and methods for their prevention, preventive vaccinations, and a healthy lifestyle.
Secondary prevention is the early detection of cases and monitoring of persons who have been in contact with patients (hence, knowledge of the signs of the disease), regime-restrictive measures (quarantine, observation), isolation of patients.
Tertiary prevention measures include timely, adequate and effective treatment.
There is hardly a person who at least once in his life has not encountered such a problem as infectious diseases. The list of these pathologies is large and includes the well-known flu and colds, outbreaks of which are recorded in a particular region every year.
Infections can be dangerous, especially if the person has not been given adequate treatment or has not sought help at all. That is why it is worth learning more about the types of infectious diseases, their features, main symptoms, methods of diagnosis and therapy.
Infectious diseases: list and classification
Infectious diseases have accompanied humanity throughout history. One has only to recall the plague epidemics that destroyed more than 50% of the population of Europe. Today, medicine, of course, has learned to cope with a huge number of infections, many of which were considered fatal even a few centuries ago.
There are several systems for classifying infectious diseases. For example, they distinguish intestinal ailments and blood diseases, lesions of the respiratory tract and skin. But most often pathologies are classified depending on the nature of the pathogen:
- prion (fatal familial insomnia, kuru);
- bacterial (salmonellosis, cholera, anthrax);
- viral (influenza, measles, parotitis, HIV infection, hepatitis);
- fungal, or mycotic (thrush);
- protozoan (malaria, amoebiasis).
Transmission routes and risk factors
Infectious agents can enter the body in different ways. There are such ways of infection:
- The alimentary route, in which pathogens enter the body through the digestive tract (for example, along with unwashed food, contaminated water, due to dirty hands).
- Airborne transmission, in which pathogens are introduced through the respiratory system. For example, pathogens can be found in dust. In addition, microorganisms are released into the external environment along with mucus during coughing and sneezing.
- Contact infection occurs when sharing household items or toys, direct contact with the skin of a sick person. When it comes to sexually transmitted diseases, the transmission of infection occurs during sexual intercourse.
- Pathogenic microorganisms are often transmitted from person to person along with the blood. Infection can occur during a blood transfusion, as a result of the use of non-sterile instruments, and not only medical ones. For example, you can catch an infection while doing a manicure. Often, pathogenic microorganisms are transmitted from a sick mother to a child during pregnancy or childbirth. Insects can also be carriers.
It is impossible to completely exclude the possibility of infection in the body. But some people are more prone to this type of disease, and such diseases are much more difficult for them. Why? When infectious agents spread throughout the body, the state of the immune system is of great importance. Dysbacteriosis, anemia, beriberi, weakened immunity - all this creates ideal conditions for the rapid reproduction of pathogens.
Risk factors include severe hypothermia, a sedentary lifestyle, unhealthy diet, bad habits, hormonal disruptions, constant stress, and poor personal hygiene.
Varieties of viral diseases
There are a huge number of viral infections. Here are just a few of them:
- All types of flu, colds (in particular, rhinovirus infection), which are accompanied by general weakness, fever, runny nose, cough, sore throat.
- It is worth mentioning the so-called childhood infections. This group includes rubella, accompanied by damage to the skin, respiratory tract, cervical lymph nodes. Mumps (known as mumps) is also a viral disease that affects the salivary glands and lymph nodes. The list of such infections includes measles, chicken pox.
- Hepatitis is a disease that causes inflammation of the liver. In most cases, the virus is transmitted through the blood (types C and D). But there are also strains that spread by household and alimentary routes (hepatitis A and B). In some cases, the disease leads to the development of liver failure.
- Pneumonia is an inflammation of the lungs that can have very serious consequences. The role of the causative agent can be adenoviruses, cytomegaloviruses, influenza and parainfluenza viruses. By the way, the inflammatory process can also be caused by bacteria, but the symptoms in this case are different. Signs of viral pneumonia - fever, runny nose, general weakness, unproductive cough, shortness of breath. Viral forms of inflammation are characterized by a more rapid course.
- Infectious mononucleosis is considered quite common. Symptoms, treatment and consequences of this disease are of interest to many readers. The causative agent is the Epstein-Barr virus, which is transmitted from an infected person by airborne droplets, most often with saliva (by the way, this is why the disease is often called "kissing disease"). The infection affects the tissues of the pharynx, lymph nodes, liver and spleen. Against the background of the disease, a change in the composition of the blood is observed - atypical mononuclear cells appear in it. Currently, there is no specially developed treatment regimen. Doctors provide symptomatic treatment.
Prion diseases and their features
Prions are rather specific infectious agents. In fact, they are a protein with an abnormal tertiary structure. Unlike viruses, prions do not contain nucleic acids. However, they can increase their numbers (reproduce) using living cells of the body.
Most often, prion infectious diseases are diagnosed in animals. Their list is not that big. In cows, against the background of infection, the so-called mad cow disease, or spongiform encephalopathy, can develop. Prions affect the nervous system of cats, antelopes, ostriches and some other animals.
A person is also susceptible to this type of infection. Against the background of prion activity, people develop Creutzfeldt-Jakob disease, Gerstmann syndrome, fatal familial insomnia.
Bacterial infections
The number of bacterial organisms that can lead to the development of a disease when it enters the human body is huge. Let's take a look at some of the infections.
Salmonellosis. This term unites a whole group of acute infectious diseases that affect the human digestive tract. Bacterial microorganisms of the genus Salmonella act as pathogens. The incubation period lasts from 6 hours to 8 days. The first symptoms are abdominal pain. As the disease progresses, pathogenic agents can affect the organs of the central nervous system and the cardiovascular system.
Botulism. Another disease from the group of intestinal infections. The causative agent is the bacterium Clostridium botulinum. This microorganism, penetrating the wall of the digestive tract, begins to release botulinum toxin, which is dangerous for humans. Signs of botulism are severe abdominal pain, weakness, vomiting, diarrhea, and fever. By the way, most often the pathogen enters the body with food.
Dysentery is an acute intestinal infection caused by a bacterium of the genus Shigella. The disease begins with a simple malaise and a slight increase in temperature, but then other disorders appear, in particular severe diarrhea. The disease is dangerous, as it can lead to damage to the intestinal mucosa and dehydration.
anthrax is a very dangerous disease. It starts acutely and develops very quickly. What are the symptoms of the disease? Anthrax is characterized by serous-hemorrhagic inflammation of the skin, serious lesions of internal organs and lymph nodes. The disease often ends in the death of the patient, even with properly administered therapy.
Lyme disease. Symptoms of the disease are fever, fatigue, skin rash, headaches. The causative agents are bacteria of the genus Borrelia. The infection is carried by ixodid ticks. Sometimes, against the background of infection, an inflammatory lesion of the heart, joints and nervous system is observed.
Venereal diseases. Not to mention sexually transmitted infections. Bacterial diseases include gonorrhea, ureaplasmosis, chlamydia, mycoplasmosis. Sexual syphilis is also dangerous. In the initial stages, this disease is easily treatable, but if left untreated, the pathogen affects almost all organs, including the brain.
Quite common are diseases caused by meningococci. These pathogens are spread by airborne droplets. Forms meningococcal infection may be different. Against the background of infection of the body, pneumonia, meningitis, meningoencephalitis develops. Much less frequently, patients are diagnosed with endocarditis and arthritis.
Mycoses: fungal infections of the body
Mycoses are infectious diseases caused by the penetration of pathogenic fungi into the human body.
Perhaps the most common and well-known disease of this group is candidiasis(thrush). The infection affects the mucous membranes of the genital organs, the oral cavity, less often the skin in the natural folds of the body. A characteristic feature is the formation of a white cheesy plaque with a sour smell.
Onychomycosis- a group of common ailments, the causative agents of which are dermatophyte fungi. Microorganisms infect the nails on the hands and feet, gradually destroying the nail plate.
Other fungal diseases include seborrhea, pityriasis versicolor, ringworm, sporotrichosis and many others.
Protozoal diseases
Malaria A disease caused by plasmodium. The disease is accompanied by the development of anemia, repeated bouts of fever, an increase in the size of the spleen. The causative agent of malaria enters the body through the bite of a malarial mosquito. These protozoa are common in some countries of Africa, Asia and South America.
The group of protozoan diseases also includes amoebiasis(pathogen - amoeba), leishmaniasis(the causative agent is leishmania, which enters the human body through the bite of a mosquito), sarcocystosis, toxoplasmosis, trichomoniasis, sleeping sickness, giardiasis(accompanied by damage to the digestive tract and skin).
Common signs of infectious diseases
There are a huge number of symptoms that can accompany infectious diseases. The list of them can be discussed endlessly, because each ailment has its own, unique characteristics. Nevertheless, there are a number of common signs that are present in any infectious disease:
- An increase in body temperature is observed in almost any infectious lesion of the body.
- It is worth mentioning the symptoms of intoxication - these are headaches, body aches, muscle pain, weakness, drowsiness, fatigue.
- Cough, runny nose, sore throat appear when the respiratory tract is infected (for example, a rhinovirus infection can lead to the appearance of such symptoms).
- The appearance of a rash and redness on the skin that does not disappear with the use of antihistamines.
- Gastrointestinal disorders, including abdominal pain, stool disorders, nausea and vomiting. With liver damage, the color of the skin and sclera of the eyes changes (this is how hepatitis A develops).
Of course, each disease has its own characteristics. An example is Lyme disease, the symptoms of which are the appearance of migratory ring redness on the skin, fever, damage to the nervous system with the further development of depressive states.
Diagnosis of infectious diseases
As you can see, infectious diseases are very diverse. Of course, for proper treatment it is extremely important to determine the nature of the pathogen in time. This can be done through laboratory research. They can be divided into three groups:
- Direct diagnostic methods
The purpose of research is to accurately identify the pathogen. Until recently, the only way to conduct such an analysis was to inoculate samples taken from a patient on a special medium. Further cultivation of the culture of microorganisms made it possible to identify the pathogen and even assess the degree of its sensitivity to certain drugs. This technique is used to this day, but it takes a long time (sometimes 10 days).
A faster method is PCR diagnostics, aimed at identifying certain fragments of the pathogen (usually DNA or RNA) in the patient's blood. This technique is especially effective in viral diseases.
- Indirect diagnostic methods
This group includes laboratory studies in which they study not pathogens, but the reaction of the human body to them. When an infection enters, the immune system begins to produce antigens, in particular immunoglobulins. These are specific proteins. Depending on the structure of the antibodies present in the blood, the doctor can judge the development of a particular infectious disease.
- Paraclinical methods
This includes studies that can help determine the symptoms of the disease and the degree of damage to the body. For example, a blood test confirms the presence of an inflammatory process in the body. Infectious damage to the kidneys affects the functioning of the excretory system - any failures can be detected by examining urine samples. The same methods include ultrasound, X-ray, MRI and other instrumental studies.
What does the treatment depend on?
How are infectious diseases treated? The list of them is huge, and the treatment regimens are varied. In this case, it all depends on the nature of the pathogen, the general condition of the patient, the severity of the disease and other factors.
For example, for bacterial infections, broad-spectrum antibiotics are used. These drugs will be useless for viral diseases, because in such cases the patient needs to take antiviral drugs, interferon and immunomodulators. The presence of mycoses is an indication for taking antifungal agents.
Of course, symptomatic therapy is also carried out. Depending on the symptoms, it includes taking anti-inflammatory, antipyretic, painkillers and antihistamines. A rhinovirus infection, for example, will clear up more easily with special nasal drops. With lesions of the respiratory system, accompanied by a cough, specialists prescribe expectorant syrups and antitussive drugs.
It should be understood that self-medication is impossible in any case. For example, if you find signs of botulism in yourself, you should immediately consult a doctor, as this is a serious disease - in the absence of therapy, serious consequences are possible, especially when it comes to the body of a child.
Preventive actions
It is much easier to prevent an infection than to treat it later. Prevention of infectious diseases should be comprehensive. A person is constantly in contact with pathogenic microorganisms - they are present in the air and in water, get into food, settle on door handles and household items. Therefore, it is important to strengthen the body.
A strong immune system is able to suppress the reproduction of pathogenic microbes that have already entered the human body. Proper nutrition, regular physical activity, outdoor walks, hardening, proper sleep and rest, lack of stress - all this helps to increase the body's defenses.
Do not give up vaccinations. Timely vaccination can protect against pathogens such as mumps, polio and hepatitis, etc. The preparations used for vaccinations contain samples of a dead or weakened pathogen of a particular disease - they cannot cause serious harm to the body, but help to develop strong immunity.
Many people turn to doctors after traveling. The fact is that in some regions of the planet various infectious diseases are rampant. For example, the causative agent of malaria (Plasmodium) enters the human blood only when bitten by a malarial mosquito, which lives only in some regions of Africa, Asia and South America. If you are going to spend some time in a particular country (especially if we are talking about countries with a tropical climate), be sure to ask about the level of spread of a particular infection - it is quite possible that it is better to get vaccinated or stock up on medicines before the trip.
Of course, it is very important to observe hygiene standards, buy high-quality food, wash them before use, and cook them properly. During epidemic outbreaks of influenza or other colds, it is worth avoiding crowded places, taking special drugs to strengthen immunity (for example, Aflubin). To protect against sexual infections during intercourse, it is imperative to use a condom.
Infectious (contagious) diseases occupy a special place among other human diseases. The most important feature of infectious diseases is their contagiousness, i.e., the possibility of transmission from a sick person or animal to a healthy one. Many of these diseases, such as influenza, are capable of mass (epidemic) spread, covering, under appropriate conditions, the entire village, city, region, country, etc. continents.
One of the reasons for the mass spread of infectious diseases is the low sanitary culture of the population, non-compliance with various sanitary and hygienic rules. In this regard, sanitary teams with appropriate training can play an important role in raising the sanitary culture among the population, in inculcating hygienic skills in it. In addition, it is important to carry out a number of anti-epidemic measures, such as sanitary supervision of catering establishments, the condition of dwellings and public places. Health care workers can be of great help in this regard. With the mass spread of infectious diseases, especially when the enemy uses bacteriological (biological) weapons, sanitary squads can also be involved in many other anti-epidemic measures.
Infectious diseases are caused by microbes (microorganisms) that are very small in size; Microorganisms are studied with a microscope. A modern electron microscope gives a magnification of 200,000 times or more. The size of microbes is usually expressed in thousandths of a millimeter - microns. The world of microbes is extremely large and diverse. Microorganisms are found in large numbers in soil, water, and air. Without the participation of microorganisms, the cycle of substances in nature is impossible. Microorganisms take part in the enrichment of the soil with mineral compounds and nitrogen, decompose corpses and plants (rotting), and participate in many chemical reactions. With the help of some microbes (yeast), wine, kefir, curdled milk and many other products are obtained. Numerous types of microbes inhabit the intestines of human animals, live on the skin and in the oral cavity.
Such widespread therapeutic agents as antibiotics (penicillin, streptomycin, chloramphenicol, tetracycline, gramicidin) are products produced by microorganisms.
Along with useful microorganisms, there are also harmful ones. Some of them are causative agents of contagious (infectious) diseases of humans, animals and agricultural plants. These microbes are pathogenic.
There are the following main groups of microorganisms.
1. Bacteria are unicellular organisms that reproduce by simple division (Fig. 30).
Some bacteria, such as anthrax and tetanus, under adverse conditions form spores with a dense shell, which are very resistant to drying, heat, sunlight, and chemicals.
2. Mushrooms have a more complex structure. For the most part, fungi are multicellular organisms, the cells of which have an elongated shape resembling threads.
3. The simplest - unicellular organisms of animal origin, in which there is protoplasm and. well-defined core. Some protozoa have vacuoles that perform the functions of digestion, excretion, etc.
Pathogenic microbes produce special substances - toxins with toxic properties. Toxins secreted by microbes during their lifetime are called exotoxins. Endotoxins are released only after the death and destruction of the microbial cell and are present in all pathogenic microbes. Exotoxins are produced only by some of them (tetanus, diphtheria, botulism and a number of other pathogens) and are strong poisons that act mainly on the nervous and cardiovascular systems of the body.
The direct cause of the disease is the introduction of a pathogenic microorganism into the human body or its poisoning with a toxin.
The causative agents of infectious diseases are transmitted from sick to healthy in various ways. The spread of infectious diseases in the human team is called the epidemic process. . This process is a complex phenomenon, which, in addition to the properties of the pathogen and the state of the human body, is also greatly influenced by social factors: the material condition and density of the population, the nature of nutrition and water supply, the availability of medical care, the degree of sanitary culture, etc.
In the process of the spread of infectious diseases, three links are distinguished: 1) the source of the infectious agent; 2) transmission mechanism; 3) the susceptibility of the population. Without these links, or factors, new infections cannot occur.
Source of the infectious agent. In most diseases, the source of the infectious agent is a sick person or a sick animal, from the body of which the pathogen is excreted by sneezing, coughing, urinating, vomiting, defecation. Sometimes, even after recovery, a person can secrete pathogenic microbes for a long time. Such people are called bacteria carriers (bacteria excretors). In addition, there are so-called healthy bacteria carriers - people who themselves either did not get sick or suffered the disease in the mildest form (and therefore it remained unrecognized), but became bacteria carriers. Sometimes bacteria carriers periodically secrete pathogens into the external environment for many years. Bacteriocarrier is observed in diphtheria, typhoid fever, dysentery and some other diseases.
If the main source of the infectious agent are animals from which human infection occurs, such diseases are called zoonoses. A person can become infected from a sick animal not only by direct contact with it (bite by a rabid animal, manual removal of the placenta during lambing, carcass processing, etc.), but also by eating meat and milk obtained from sick animals.
The source of the causative agent of infection can be not only domestic animals, but also rodents. Rats, various types of mice, marmots, ground squirrels, tarbagans, etc. are natural keepers (reservoirs) of pathogens of many human infectious diseases (plague, tularemia, leptospirosis, encephalitis, leishmaniasis, tick-borne relapsing fever, etc.).
pathogen transmission mechanism.After the release of the pathogen from the source (infected organism) into the external environment, it may die, but it can remain in it for a long time until it reaches a healthy person. The survival time of the pathogen depends both on the environmental conditions and on the properties of the pathogen itself. In food products, for example, in meat, milk, various creams, the causative agents of many infectious diseases can live for a long time and even multiply.
The transmission of pathogens involves water, air, food, soil, etc.
foodroute of transmission of infectious agentslesne is one of the most common. The causative agents of typhoid fever, cholera, dysentery, brucellosis, Botkin's disease, poliomyelitis, etc. are transmitted this way. In this case, the causative agents of these diseases can get on food products in various ways. This can happen both from a sick person or a bacteria carrier, and from people around him who do not follow the rules of personal hygiene. If their hands are contaminated with patient or carrier faeces containing pathogens, they can transfer them to processed foods. Therefore, intestinal infectious diseases are sometimes called "dirty hands disease".
A certain role in the spread of pathogens of intestinal infectious diseases belongs to flies. Sitting on dirty bedpans, feces, various sewage, flies pollute their paws and suck pathogenic bacteria into their intestinal tube, and then transfer them to food products and utensils.
Pathogens of cholera, typhoid and paratyphoid, dysentery, tularemia, brucellosis, leptospirosis, etc. can be transmitted through water contaminated with feces. The transmission of pathogens occurs both when drinking contaminated water, and when washing food with it, as well as when bathing in it. The transmission of the pathogen through the air occurs when talking, exhaling, kissing, but more often when coughing and sneezing with droplets of mucus (“drip transmission of the pathogen”). Some microbes can also be transmitted by dust particles (dust path).
Many pathogens of infectious diseases are transmitted by blood-sucking arthropod vectors. Having sucked the blood of a sick person or animal containing pathogens, the carrier becomes contagious. Attacking then on a healthy person, the carrier infects him. In this way, fleas transmit the causative agent of plague, lice - typhus and relapsing fever, mosquitoes - malaria, ticks - encephalitis, etc.
In cases where pathogens are transmitted through contact of the patient or his secretions with a healthy person, they speak of a contact-household transmission route.
The susceptibility of the population. Everyone knows that the susceptibility of people to various pathogens of infectious diseases is not the same. There are pathogens to which all people are susceptible (smallpox, measles, influenza, etc.). To other pathogens, on the contrary, the susceptibility is very low. The susceptibility of the population - can be significantly reduced by carrying out preventive vaccinations aimed at increasing specific immunity (immunity).
Immunity is a property of the body that ensures its immunity to infectious diseases or poisons.
The human body has a number of protective devices that prevent the penetration of pathogenic microbes or due to which they die in the body. First of all, it is necessary to note the great protective role of the skin and mucous membranes. Saliva, tears, gastric and intestinal juice have antimicrobial properties. The further spread of microbes is prevented by the lymph nodes, in which the microbes linger and then die.
The founder of the doctrine of immunity, the great Russian scientist I. I. Mechnikov (1845-1916), established that white blood cells - leukocytes are able to capture live pathogenic microbes and destroy them. This phenomenon was called by I. I. Mechnikov phagocytosis. Along with phagocytes, for the state of immunity of the body, special substances are important - antibodies, which are located mainly in the blood, lymph and many tissues.
A lot of antibodies accumulate in the blood of animals (for example, horses), if they are repeatedly injected subcutaneously with killed microbes or neutralized toxins. Specific therapeutic sera are prepared from the blood of such horses.
Immunity to infectious diseases manifests itself in several forms.
Natural immunity arises naturally, without conscious human intervention, for example, as a result of an infectious disease. After some infectious diseases (natural smallpox, measles, typhoid fever, etc.), immunity persists for a long time, sometimes for life, after others (flu) - for a short time. Natural immunity to certain diseases (measles, scarlet fever, diphtheria) is also observed in children in the first months of life, which is associated with the preservation of the protective bodies they received from mothers who had had these diseases in the past.
Artificial immunity is created by the introduction of vaccines or sera in order to prevent a particular disease. Preparations with the help of which it is possible to artificially create the body's immunity, that is, immunity, are called vaccines and toxoids. Currently, a variety of vaccines are being produced: 1) from live attenuated pathogens; 2) from killed microbes; 3) chemical vaccines prepared from products of chemical breakdown of microbial cells; 4) toxoids, which are neutralized toxins.
Immunity after the introduction of killed vaccines is shorter (up to 1 year) than after the introduction of live vaccines, in which immunity sometimes persists for 3-5 years. After the specified period, revaccination (re-vaccination) is carried out.
In the USSR, vaccinations against smallpox, diphtheria, tuberculosis, poliomyelitis and some other diseases are mandatory and are carried out for all children, and anti-smallpox vaccinations for adults as well. In addition, there are combination vaccines; after inoculation with such a vaccine, immunity against several diseases arises.
The widespread use of preventive vaccinations has proven to be a highly effective method of combating infectious diseases. Suffice it to recall that the implementation of mandatory smallpox vaccination, established in our country back in 1919 by a decree of the Council of People's Commissars signed by V. I. Lenin, ensured success in the fight against smallpox, this serious disease, completely eliminated in the territory of the Soviet Union.
It should be emphasized that the basis for the prevention of infectious diseases is the implementation of broad sanitary-hygienic and general anti-epidemic measures, and the use of prophylactic vaccinations is of secondary importance. First of all, success is ensured by general sanitary measures, which are carried out regardless of the presence of diseases. These are sanitary control over water supply and food enterprises, cleaning up populated areas from sewage, fighting the breeding of flies, draining swamps, introducing water pipes and sewers, etc. General sanitary measures play a decisive role, especially in the prevention of intestinal infectious diseases. Early detection and isolation of infectious patients are of great importance in preventing further transmission of the infectious agent. In most cases, they are hospitalized in specialized infectious diseases departments or hospitals, and only for some infectious diseases (scarlet fever, measles, influenza, in some cases dysentery) is isolation at home allowed. In these cases, all possible measures are taken in these conditions to isolate the patient from others: he is placed in a separate room or, in extreme cases, behind a screen, the patient's excretions are neutralized, etc. Infectious patients are strictly forbidden to visit public places, including an outpatient clinic and a clinic.
Infectious patients are transported by special transport. After each patient, the machine is subjected to processing (disinfection, disinsection).
A significant place in the comprehensive prevention of infectious diseases belongs to the promotion of hygiene and cultural skills among the population. The sanitary combatant should be an active assistant to the doctor and nurse in conducting sanitary and educational work and set an example in observing hygiene and cultural skills. In a conversation, she can talk about the source of a particular infection, ways of its spread, teach others about the simplest preventive measures: isolating the patient, ventilating the room, neutralizing dishes and household items by boiling, etc.
If necessary, sanitary combatants can be involved in house-to-house rounds, the purpose of which is to identify all febrile patients during an epidemic outbreak of certain diseases for subsequent hospitalization.
Disinfection, disinsection and deratization play a huge role in preventing further transmission of the infectious agent;
Disinfection - disinfection. In the practice of disinfection, two types of it are distinguished: focal and prophylactic.
Preventive disinfection is carried out in order to improve the health of populated areas and prevent the occurrence of diseases, regardless of their presence. This is airing rooms, wet cleaning rooms, washing hands before eating, cleaning and chlorinating tap water at a water pumping station, pasteurizing and boiling milk, canning food, etc.
Focal disinfection is carried out in those cases when it becomes known about the appearance of a disease in a family, a hostel, a children's institution, that is, in an epidemic focus. Depending on the stage at which disinfection is carried out, current and final disinfection is distinguished.
Current disinfection is carried out in the focus of infection in order to destroy pathogens immediately after they are isolated from the patient's body. To this end, every portion of feces and urine is neutralized, if we are talking about intestinal infections, sputum of tuberculosis patients, etc.
Disinfect also objects used by the patient, his linen, as it may be contaminated with feces containing pathogens. They systematically wash the walls, floors, beds, bedside tables with disinfectant solutions, wash with soap, boil toys, linen, dishes.
One of the most important moments of the current disinfection is the strict observance of the rules of personal hygiene and the development of appropriate skills by all persons caring for the sick.
The final disinfection is carried out by specially trained disinfectors after the patient is hospitalized, recovered, transferred to another room or died.
Disinfection is carried out using physical and chemical means. One of the methods of physical purification of tap water is filtration. Direct sunlight also has a detrimental effect on many pathogenic microbes.
Ultraviolet rays are highly bactericidal. To obtain them, mercury-quartz and uviol lamps are used, which are used to disinfect the air and surfaces of various indoor items.
Dishes, bedpans, spittoons, surgical instruments, syringes, needles, brushes, etc. are disinfected in boiling water for at least 45 minutes. Linen is also often disinfected by boiling.
Chemical methods of disinfection are the most common. Various chemicals are used for disinfection: phenol, cresols, lysol, alcohols, various alkalis and acids, bleach, etc. Disinfection is carried out according to special instructions approved by the USSR Ministry of Health.
The most commonly used is bleach, from which, during its decomposition, free oxygen and free chlorine are released, which have a detrimental effect on the vital activity of the microbial cell. Chloric lime is used for disinfection of secretions from intestinal infections (typhoid fever, paratyphoid fever, dysentery, cholera, etc.), respiratory diseases (diphtheria, tuberculosis), plague, anthrax, etc., as well as disinfection of linen and dishes.
For disinfection of outerwear, bedding, books and other items, formalin is widely used - a 40% aqueous solution of formaldehyde. Disinfection is carried out in special disinfection chambers.
Along with stationary cameras, there are also mobile installations on a car. Thus, the mobile steam-formalin chamber APKD (Fig. 31) has two chambers and a device that allows washing people in the shower simultaneously with the disinfection of things. Movable chambers allow disinfection in the field and in small settlements.
Disinfection of the surfaces of the room (floor, walls) and objects in them that cannot be sent to the disinfection chamber is carried out by spraying solutions
high-pressure disinfectants from special pumps and hydraulic panels (Fig. 32).
Disinsection - release from insects and other arthropods - is a subspecies of disinfection. As well as disinfection, disinsection is carried out using physical, chemical and biological means.
Physical methods of disinfestation are basically the same as disinfection. This is the mechanical cleaning of things with brushes, knocking out, suction with a vacuum cleaner, burning low-value items. For the destruction of insects, sticky masses and various traps are widely used. Lice and nits on linen can be destroyed by carefully ironing with a hot iron. Wearable items and soft equipment (mattresses, blankets, etc.) are subjected to disinfestation in hot-air chambers. The device of such cameras is very simple. In the absence of a special chamber, a Russian stove can be used.
Chemical pest control methods are based on the ability of certain chemicals to have a toxic effect on arthropods. The most commonly used are Parisian greens, DDT (dichlorodiphenyltrichloroethane), hexachlorocyclohexane (HCCH, hexachloran), chlorophos, etc. It must be remembered that almost all of these drugs are toxic to humans. Therefore, it is imperative to work with powders or aerosols (the smallest particles of a substance suspended in the air) in a respirator mask, with solutions and emulsions - in rubber gloves and clothing that protects the skin, and take measures to protect food and water from insecticides ( so-called chemicals that have a detrimental effect on arthropods). As a means of personal protection against the attack of blood-sucking insects, repellents are used - substances that repel arthropods: dimethyl phthalate, diethyltoluamide (DET), kyuzol, etc. Insect repellent agents are included in ointments, creams, lotions recommended for personal protection against insect attacks in the taiga, tundra .
Deratization - release from rodents - is aimed at eliminating the source of the infectious agent, which in many diseases are rodents. Extermination measures are carried out using biological, chemical and mechanical methods.
Chemical methods of deratization consist in the use of various poisons, usually mixed with bait (bread, cereals, vegetables, etc.). Various poisons and baits are used for different types of rodents: ratsid, zinc phosphide, zoocoumarin, etc.
Biological methods for the destruction of rodents are reduced to the use of cats, rat-traps, etc., mechanical - to the use of traps and traps.
Source---
Textbook for sanitary combatants. M.: Medicine, 1972.- 192 p.
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INFECTIOUS DISEASES AND THEIR PREVENTION
1. The doctrine of infection and the infectious process
3. Formation of immunity
disease infectious immunity vaccination
1. Infectious diseases - a group of diseases caused by pathogenic or opportunistic microorganisms, characterized by a cyclical process and the formation of specific immunity.
The infectious process is the result of the interaction of micro- and macro-organisms under the influence of the external environment. If, as a result of such an interaction, a pathological process develops with certain clinical symptoms, this means that an infectious disease has arisen.
The cause of an infectious disease is the introduction of a pathogen into the body. Infection causes the development of an infectious process, which does not always lead to the development of the disease. The following factors are of great importance in the occurrence and course of an infectious disease: socio-economic (nutrition, living and working conditions, organization of medical care), age, climatic, and the state of the immune system. Infectious diseases have a number of features: contagiousness (infectiousness), specificity (each infectious disease is caused by a specific pathogen, has characteristic clinical features), cyclicity, i.e. the presence of certain periods (cycles) of the course of the disease: incubation, prodromal, peak of the disease, extinction, recovery period, development of immunity in the body after the disease.
For example, tetanus toxin affects the motor neurons of the anterior horns of the spinal cord, diphtheria bacillus toxins - epithelial cells, heart muscle cells. Since exotoxins are proteins, they are destroyed when exposed to high temperature. It is used in the prevention of botulism. If canned mushrooms are believed to contain botulinum toxin, then such mushrooms are boiled, while the botulinum exotoxin is destroyed and the product can be eaten. With a certain processing, exotoxins can lose their toxic properties, but retain their immunogenic properties (the ability to produce antibodies - antitoxins when introduced into the body). Neutralized preparations of toxins are called antitoxins and are used in immunization against diphtheria, tetanus, etc.
Endotoxins are produced by gram-negative bacteria, are more often formed during cell destruction, have a lipopolysaccharide nature, they are thermostable. Endotoxins do not have a pronounced specificity; under their influence, nonspecific immunity factors are activated and symptoms of intoxication develop (weakness, nausea, headache, muscle and lower back pain), and the temperature also rises.
The interaction of micro- and macroorganisms does not always end in the development of the disease. In cases where, with such an interaction, the pathological process does not develop, there are no clinical symptoms of the disease, and the pathogen is in the body, they speak of a healthy carriage.
Microbes enter the body in various ways: through the skin, mucous membranes, respiratory tract, digestive tract. The place of introduction of the microbe is called the "entrance gate". From the site of initial introduction, microbes spread throughout the body. They are also excreted from the patient's body in various ways - with feces, urine, sputum.
According to the duration of the release of the pathogen, acute and chronic carriage are distinguished. In some diseases, there is a tendency to form a carrier state (typhoid fever, salmonellosis, dysentery, diphtheria), in other diseases this form is absent (smallpox, plague, influenza, glanders). Since the carriers of the causative agent of the disease most often do not know about the release of pathogenic microbes into the environment and therefore do not comply with the necessary sanitary regime, their danger to others exceeds the danger posed by the sick with the presence of clinical symptoms of the disease. Massive release of pathogens begins at the end of the incubation period, reaches a maximum during the height of the disease and decreases during the recovery period. In most cases, the isolation of bacteria lasts no more than three months (acute bacteria), but sometimes persists for life (chronic bacteria). Chronic bacterial excretors and patients suffering from erased and mild forms of the disease are the main sources of infection.
Many infectious diseases can take on a mass character and spread to entire regions. They are called epidemics. If the epidemic extends beyond the borders of the country and covers large areas, it is called a pandemic; Influenza is a typical pandemic in recent decades. Single cases of contagious diseases, recurring from year to year in some separate, limited area, are called endemic. Infections transmitted from animals to humans are called zoonoses.
The urgency of the fight against infectious diseases and its complexity served as a reason to single out an independent science - epidemiology, whose task is to identify the sources of infection, study the mechanisms of infection, the patterns of occurrence and ways of spread and extinction of mass epidemic diseases, as well as the development of measures to combat them.
2. Features of infectious diseases
In addition to the main feature of infectious diseases - the ability to be transmitted from sick people to healthy ones - there are features in the occurrence and course of these diseases. They, as a rule, are acutely febrile, occur with an increase in body temperature and are distinguished by a cyclic course of the disease with pronounced individual periods.
The first, latent, or incubation, period of the disease begins from the moment the pathogen enters the body until the first clinical symptoms of the disease appear in the patient. It covers the time it takes for microbes to multiply and develop their ability to cause disease. The duration of this period is different for different diseases. For example, with cholera - a few hours, with influenza - an average of 2 days, with diphtheria - 5 days, with tetanus - 7-10 days, with typhus - 14 days, etc. If microbes enter the body in large numbers or have high virulence (toxigenic properties), the incubation period may be shorter. It also happens when a person is weakened and his body does not provide adequate resistance to infection. With a number of infections, for example, measles, diphtheria, already in the first period, a person becomes dangerous to others.
The second, so-called prodromal period, which is the period of precursors of the disease, is characterized by the appearance of the first non-specific symptoms (malaise, general weakness, headache, loss of appetite, often fever). It lasts from several hours (scarlet fever, plague) to several days (smallpox, measles, typhoid fever). In some forms of the disease, the prodromal period may be absent.
Then comes the third period - the period of the height of the disease. It is characterized by the most pronounced non-specific symptoms, as well as the appearance of specific symptoms that are characteristic only for this disease (jaundice in viral hepatitis, diarrhea in cholera, etc.). The duration of the period depends on the characteristics of a particular disease.
Finally, if the patient coped with the disease, the fourth period begins - the period of recovery. All clinical symptoms gradually disappear, the structure and functions of the affected organs are restored. In some cases, the symptoms of the disease disappear gradually, in others quickly - like a crisis.
Infectious diseases are usually divided into typical and atypical forms of the disease. Atypical forms are called forms of the disease that occur with the absence of a number of typical symptoms. Among atypical forms, erased and inapparat (subclinical) forms stand out. The inactive form is a form of the disease that does not manifest itself clinically, but is diagnosed by laboratory tests. Superinfection is the layering of a pathogen of a different type of infection on an already existing infectious disease. Reinfection is a repeated infectious disease caused by the same pathogen. An exacerbation is a return of the symptoms of the height of the disease in a patient who has not yet fully recovered. Relapse is the return of the main symptoms of the disease in a person who is in the stage of complete recovery from an infectious disease.
In terms of duration, the course of an infectious disease can be acute (from 1 to 3 months), protracted (from 4 to 6 months) and chronic (over 6 months). Depending on the ways and means of transmission of infection and the localization of the infectious process, infectious diseases are divided into 5 groups: 1) intestinal infections; 2) airborne infections (respiratory tract infections); 3) blood infections (hematogenous) infections; 4) infections of the outer integument; 5) zoonotic infections (transmitted from animals to humans).
3. Formation of immunity
In the process of developing an infectious disease, a specific immunity is formed in a person.
Immunity is one of the forms of protection of the body from substances or other organisms that have a genetic foreignness.
Genetic foreignness or antigenicity is ultimately due to the biochemical characteristics of the influencing factor (antigen) and always causes the formation of special proteins (antibodies) in the body that bind and neutralize the action of the antigen. Antigenic properties are possessed by viruses, bacteria, many protozoa, helminths and other pathogens that produce substances harmful to the organism into which they enter in the course of their vital activity. Antigenicity is also characteristic of various cells of the host organism in the case when these cells are regenerated (for example, in cancer, tumor cells are genetically different from cells of neighboring tissue).
Immunity is divided into non-specific and specific. Nonspecific immunity (nonspecific resistance) is a system of measures of protection against pathogens, which does not depend on the type of pathogen and has the same type, regardless of the type of pathogen. The barriers of nonspecific resistance include: the state of the neuroendocrine system, the temperature reaction. Integrity of the skin and mucous membranes, peristalsis, normal microflora of the skin and mucous membranes, acidity of gastric juice.
When the barriers of nonspecific immunity are damaged, the body's resistance to pathogens decreases. So, in patients with chronic gastritis, the possibility of infection with intestinal infections increases dramatically. There is a high probability of developing sepsis in a patient with extensive burns. A patient undergoing treatment in a hospital undergoes various manipulations and injections. In these cases, if the rules of asepsis and antisepsis are not followed, conditions for nosocomial infection arise, which is also facilitated by a decrease in nonspecific protection due to damage to the mechanical barrier (violation of the integrity of the skin).
Under the influence of a pathogen, along with nonspecific immunity, specific immunity develops, which is divided into cellular and humoral.
Humoral immunity is mediated by B-lymphocytes, and the result of its action is the production of specific antibodies. The purpose of antibody production is the formation of an antigen-antibody complex, which is subsequently destroyed. Thus, the pathogen is removed from the body.
In parallel with specific humoral immunity, cellular immunity develops. Cellular immunity is mediated by T-lymphocytes, which have different specificities.
Immunity can be innate, received from the mother. Innate immunity (species, hereditary, natural, constitutional immunity) is inherent in one or another type of animal and is inherited, like other genetic traits. So, people are immune to rinderpest, dogs, in turn, animals are immune to the causative agent of measles, meningitis and some other diseases that people suffer from.
There is a different severity of innate immunity - from absolute resistance to any microorganism, which is rarely observed, to relative immunity, which can be overcome as a result of various influences (increasing the dose of an infecting agent, general weakening of the body, for example, with a decrease in temperature).
Acquired immunity occurs as a result of an acquired infectious disease or after vaccination and is not inherited. One of the main features of acquired immunity is its strict specificity: it is produced only to a certain microorganism (antigen) that has entered or introduced into the body.
Distinguish between active and passive acquired immunity. Acquired active immunity may result from the transmission of a disease or through vaccination. Actively acquired immunity is established 1-2 weeks after the onset of the disease and persists for a relatively long time - for years or tens of years. For example, after measles remains for life. In other infections, such as influenza, actively acquired immunity does not last long.
Passively acquired immunity occurs in the fetus due to the fact that it receives antibodies from the mother through the placenta, so newborns remain immune to certain infectious diseases, such as measles, for a certain time. Passively acquired immunity can also be created artificially by introducing into the body antibodies obtained from recovered or vaccinated people or animals. Passively acquired immunity is established quickly - a few hours after the introduction of immunoglobulin and persists for a short time (within 3-4 weeks).
Thus, the joint action of nonspecific resistance, specific humoral and cellular immunity is aimed at protecting the body from pathogens of infectious diseases, and even in the case of the development of the disease, it ensures the cyclical course of its course with recovery.
However, sometimes in the process of developing immunity, immunopathological reactions also develop, and then immunity instead of the function of protection carries the function of damage.
One of the options for such immunopathological conditions is the development of allergies.
4. Conditions for the development of infectious diseases
For the occurrence of an infectious disease, one penetration into the body of the causative agent of this disease is not enough. Also, the presence of several patients is not enough for an epidemic to develop. In both cases, a combination of a number of external and internal factors is necessary that can contribute to the emergence and development of epidemic diseases.
The epidemic process includes the following links:
1. Source of infection.
2. Mechanisms of transmission of pathogens.
3. Susceptibility of the population (groups at risk for a particular infectious disease).
source of infection. The source of infection in most cases is a person with an erased or typical form of an infectious disease, or a bacteriocarrier. The causative agent can be released when coughing, the so-called airborne infections (flu, SARS). In intestinal infections, the pathogen is excreted during defecation with feces. In some so-called blood infections (typhus), the pathogen is in the blood and is transmitted by blood-sucking insects and arthropods. Infectious diseases that spread only among people are called anthroponotic. In cases where the source of the disease is a sick animal and the infectious principle is transmitted from it to humans, we are talking about a zoonotic or zoonotic infectious disease.
In zoonotic infectious diseases, the animal is sometimes the only source of infection, in other infections (plague) the source can be a person and an animal. A person is infected by an animal both by direct contact (bite of a rabid animal, manual separation of the placenta in brucellosis), and indirectly (through the consumption of infected products: meat, milk). The incidence of zoonoses is naturally more common among rural residents; urban populations can become infected by eating animal products. The source or reservoir of infection can be not only domestic animals, but also wild animals (boars with trichinosis) and rodents (rats, mice, ground squirrels, etc.).
In the human body, the pathogen multiplies in various organs and systems: a) the digestive tract; b) respiratory organs; c) liver; d) circulatory system and spleen; e) kidneys; f) skin and its appendages, including mucous membranes. After the pathogen has been released into the external environment (soil, water, air), the length of stay and the ability to exist in it matter. Many pathogens are detrimental to the sun's rays, drying. Others are quite stable in the external environment (hepatitis B virus), especially those with spores (the causative agent of tetanus, botulism, etc.).
Very quickly, within a few minutes, the pathogens of influenza, meningococcal infection, gonorrhea die. other microorganisms. Adapted to survive outside the body. The causative agents of anthrax, tetanus and botulism form spores and can persist in the soil for decades. In food products. For example, in milk, the causative agents of many infectious diseases live for a long time and even multiply. The degree of stability of the pathogen in the external environment is of great importance in epidemiology, in particular in the selection and development of a set of anti-epidemic measures. Various environmental factors (water, air, soil, foodstuffs, household items, insects) are involved in the transmission of the infectious principle, which determine the ways of infection transmission.
Contact transmission occurs when the patient comes in contact with a healthy person. Contact can be direct in direct contact with the patient or his secretions and indirect, indirect, through household items (toys, dishes, etc.) and industrial purposes.
Intestinal infections are most often transmitted by food. Patients or carriers infect food in various ways. Of particular importance is the contamination of hands with pathogens, and then the introduction of infection through food into the body, which is why intestinal infections are called "diseases of dirty hands." The spread of infections at present most often occurs through milk and dairy products, meat obtained from animals with zoonoses. It should be noted that food products can serve as a nutrient medium for the accumulation and reproduction of microbes (Salmonella, dysentery bacillus, etc.).
The role of flies in the spread of infectious diseases in our time is negligible. Some authors in the transmission of intestinal infections attach importance to cockroaches.
The water way of transmission of infectious diseases is typical for intestinal diseases (cholera, typhoid fever, dysentery, salmonellosis, etc.), when water sources are contaminated with feces. Then a person becomes ill by eating raw water or bathing in pathogen-contaminated springs.
Infections are transmitted by air, the pathogens of which are localized in the respiratory tract (meningococcal infection, influenza, SARS, plague, etc.). These infections form an airborne transmission route, and in infections whose pathogens are resistant to listening (anthrax, tularemia, etc.), a transmission route with dust particles is possible - airborne.
The transmissible route of transmission operates when the infectious onset is spread by blood-sucking insects and arthropods. At the same time, some insects are mechanical carriers of infection (flies, cockroaches), others are an intermediate host, since reproduction and accumulation of the pathogen occurs in their body (lice with typhus, ticks with encephalitis, mosquitoes with malaria).
The susceptibility of the population. Susceptibility is a property of an organism and its tissues to be an optimal environment for the development and reproduction of microbes. It is the third and very important link in the epidemic chain. Susceptibility to infectious diseases varies among different population groups. It is high for especially dangerous viruses and influenza viruses, and lower for other infections. Particularly dangerous infections are also diseases in which a high incidence of a person is observed, i.e. out of 100 people who communicate with the patient, 98% fall ill (cholera, plague). Social factors, age, nutrition, the state of natural and artificial immunity play an important role in the nature of susceptibility.
Epidemic focus - the location of the source of infection with the territory surrounding it, within which the transmission of an infectious beginning is possible. The alternation of a number of epidemic foci, arising from one another and interconnected, creates an epidemic process. The incidence is determined by the number of cases of this infection per 100 thousand people. An epidemic is a significant increase in the incidence in a given area (3-10 times more than the usual level).
The development of the epidemic process is influenced by natural conditions. For certain infectious diseases, natural reservoirs of infection, caused by the spread of rodents, ticks and other arthropods infected with the pathogen (bacterium or virus), play an important role in the area. Such diseases are called endemic (tick-borne encephalitis, plague, tularemia, hemorrhagic fevers, etc.).
Of great importance in the development of the epidemic process are the social conditions of people's lives (the presence and condition of sewerage, water supply), as well as other social factors: drainage of swamps, improvement of settlements, cultural skills and sanitary culture of the population.
Thus, the epidemic process can develop only in the presence of three factors: the source of infection, the mechanism of its transmission and the susceptibility of the organism. By influencing these links, it is possible to prevent and even eliminate the epidemic process that has already arisen.
5. Combating infectious diseases
Among the anti-epidemic measures, general sanitary measures should be singled out: sanitary control over water supply and food measures, cleaning of populated areas, personal hygiene, sanitary education, and timely identification of sources of infection. This also includes measures aimed at improving work and life and strengthening the health of the population, rational nutrition, hardening, the use of physical culture and sports as non-specific factors to increase immunity, the correct mode of work and rest.
The second group consists of preventive measures aimed at preventing the mass spread of certain infections through preventive vaccinations.
The third group includes special anti-epidemic measures, which provide for special measures to combat pathogens of certain diseases along the routes of their transmission to healthy people, etc.
Measures to neutralize sources of infection. The fight against the source of infection begins immediately when an infectious disease is suspected or after a diagnosis is made. At the same time, the spread of the disease as early as possible is a paramount task, as it allows timely adoption of appropriate anti-epidemic measures. First of all, it is necessary to identify an infectious patient, isolate him for the entire period that is dangerous in an epidemic sense, and provide the necessary therapeutic assistance. In most cases, patients are hospitalized in infectious diseases departments or hospitals, and only for some infectious diseases (scarlet fever, measles, influenza, sometimes dysentery) is isolation at home allowed. In this case, the patient is placed in a separate room, his discharge is disinfected. Infectious patients are strictly forbidden to visit public places, including outpatient clinics and clinics. Infectious patients must be transported by special transport, after which the machine is processed (disinfection, disinsection).
Already at the time of hospitalization, in order to combat possible nosocomial infections, a strict division of patients according to nosological forms of the disease is ensured, taking into account the mechanism of infection transmission. When discharged from infectious patients, not only clinical, but also epidemiological data are taken into account. In some diseases (typhoid fever, dysentery), patients are discharged only after negative results of bacteriological studies. For other infectious diseases (flu), a certain period must be observed, after which the patient is no longer dangerous to others.
Measures in relation to bacteria carriers are reduced to their detection and, if possible, to isolation. Bacteriocarriers are identified by bacteriological studies conducted among persons in contact with the patient, his secretions or household items, as well as in mass studies of the population (for example, in cholera foci). Be sure to examine all applicants for work at food enterprises, children's institutions, hospitals, sanatoriums, rest homes. Bacteriocarriers are suspended from work for the duration of the carrier or even forever. Bacteria carriers should be explained what danger they pose to others. How and why they need to observe a strict hygiene regimen.
Measures in relation to animals - sources of infection are reduced in dangerous cases to their destruction. In other cases, workers establish quarantine and carry out appropriate treatment of animals.
In the focus of an infectious disease, everyone who had contact with the patient is subject to observation, sometimes they take material for bacteriological studies, thus identifying bacteria carriers. The terms of observation are set by the epidemiologist depending on the maximum duration of the incubation period of the disease. In case of a number of diseases (plague, cholera, smallpox), persons who communicated with the patient are completely isolated in special departments, medical supervision is established for them. Persons. Those who have already been infected or were in the focus of infection are injected with preparations containing ready-made antibodies (immune sera, gamma globulins, bacteriophages).
Disinfection. It provides for the neutralization and destruction of pathogens of infectious diseases in the environment, as well as carriers of these diseases (insects and rodents). Includes the actual disinfection, disinsection and deratization.
When it comes to actual disinfection, a distinction is made between preventive, current and final disinfection.
Current disinfection is carried out continuously around the patient in the focus of an infectious disease. The discharge of the patient, household items, his underwear and clothes are subjected to disinfection.
Current disinfection plays a significant role in intestinal infectious diseases. The purpose of the current disinfection is to reduce the contamination of objects surrounding the patient with pathogenic microorganisms. In case of airborne infections, an effective method of disinfection is ultraviolet irradiation with quartz lamps of rooms and wards, wet cleaning of rooms where the patient is located.
The final disinfection is carried out once in the outbreak after the patient is hospitalized in a hospital after the patient recovers or dies.
Preventive disinfection is carried out in order to prevent the emergence and spread of infectious diseases (for example, boiling water). For any type of disinfection, physical, chemical and biological methods are used.
Physical methods of disinfection are the simplest and most affordable. A common method is the mechanical removal of the infectious principle by washing, cleaning, shaking, filtering, ventilation, etc. Effectively two- and three-time washing of the walls with sodium bicarbonate or other detergents. UV rays and special bactericidal lamps have a bactericidal effect.
A good effect is obtained during disinfection by the use of high temperatures, including calcining objects in a flame (disinfection of a loop in microbiological practice, tweezers and scalpels). The corpses of dead sick animals and low-value items used by an infectious patient should be burned.
The next method of disinfection is boiling. Surgical instruments, brushes, dishes are processed in boiling water with the addition of 1-2% sodium bicarbonate solution. If disinfection by boiling is not possible, the dishes are treated chemically. Infected linen can be pre-soaked for 6-12 hours in water, to which a 0.5-1% solution of soda ash is added, and boiled for 1-1.5 hours. Disinfection with a steam-air mixture is carried out in special disinfection chambers. Processing in them is carried out both at normal and at elevated atmospheric pressure. Fur, leather and some colored items cannot be disinfected in steam chambers due to the possibility of damage.
Chemical methods of disinfection are the most common. For disinfection in these cases, various chemicals are used: phenol, alcohols, alkalis and acids, chloramine, bleach, etc.
Certain conditions are necessary to ensure chemical disinfection: 1) the use of disinfectants in liquid form (in the form of solutions or emulsions), 2) the use of optimal concentrations of disinfectants in liquid form, 3) the availability of the required amount of disinfectants to treat the object, 4) keeping time actions (exposure) of disinfectants.
Aqueous disinfectant solutions have the best effect on the pathogen cell. Dry bleach is used to disinfect the feces of patients (200 ml of bleach is required per 1 liter of disinfected feces of patients). For various infections, different exposures are used: for intestinal infections, viral hepatitis, typhoid fever - 60 minutes, for anthrax and plague - 120 minutes.
Chloric lime is poorly soluble in water, so working solutions are prepared from it in the form of 10-20% chloride-lime "milk". Disinfection utensils (spittoons, pots, bedpans, etc.) are disinfected with them with an exposure time of 30 minutes for most infections. For processing dishes and other items, a 1% solution of chloramine is used (chloramine contains 28% active chlorine and is highly soluble in water with an exposure of 30 minutes).
For disinfection of linen, treatment of walls, floors, a 3-10% soap-phenolic solution of lysol is used. It is used warm. Surfaces of objects are treated by wiping, washing or spraying chemical disinfectants.
Disinsection is included in the concept of disinfection and consists in the destruction of insects. Great importance is given to household pest control, while insects are systematically and constantly destroyed in the premises. Disinsection, like disinfection, is carried out by physical, chemical and biological methods.
Physical pest control is carried out with the help of mechanical cleaning of things with brushes, knocking out, suction with a vacuum cleaner, destruction of low-value items. Biological methods are used for malaria by breeding gambusia fish in water bodies, which eats mosquito larvae. Chemical methods of disinfection are based on the ability of some insecticides to have a detrimental effect on arthropods. Some insecticides are applied in a gaseous or vaporous state and enter the body through the respiratory tract. Others show their action in the intestines of arthropods. Contact insecticides penetrate the body of insects through the outer covers. Some of the insecticides are poisonous to humans, and also destroy beneficial insects along with pests.
As personal protective equipment, repellents are used - substances that repel blood-sucking arthropods. They are part of ointments, creams, lotions. The use of repellents reduces the risk of vector-borne infections.
Deratization is the extermination of rodents. Its purpose is not only to interrupt the transmission of infectious diseases, but also to eliminate, eliminate sources or reservoirs of a number of diseases. As a result, conditions unfavorable for the existence of rodents are created. For deratization use the same methods as for disinfection.
For chemical control of rodents, baits and poisons are used. I lay them near the holes of the holes. Biological methods - keeping cats and other animals - have been known since ancient times. Mechanical methods - the use of rat traps, mousetraps, traps.
Measures to increase the population's resistance to infectious diseases come down to promoting a healthy lifestyle in society and the formation of appropriate behavioral stereotypes. Prophylactic vaccinations serve to create individual immunity of the population.
The prevention and control of infectious diseases includes a number of measures aimed at eliminating sources of infection, eliminating the mechanisms of their transmission, and increasing the reactivity (protective properties of the body) of the population susceptible to infection. These measures are reduced to timely hospitalization and treatment of infectious patients (the leading source of the infectious process) in a hospital. Disinfection measures reduce the possibility of spreading infection. With some "blood" infections, such as typhus, an important measure is the fight against lice (disinsection), thereby interrupting the chain in the transmission of infection: man-louse-man.
Measures such as quarantine and observation contribute to the prevention of the spread of infection. Quarantine is a complex of restrictive medical and sanitary and administrative measures aimed at preventing the introduction and spread of quarantine infectious diseases (plague, cholera, etc.). Individuals, families, organized groups (kindergarten, school, ship, etc.) can be quarantined. During the quarantine, sanitary and epidemic measures are taken to be applied in case of the infection for which it was announced. At the same time, it is prohibited to move outside the quarantine zone of persons and groups of the population without prior observation.
The quarantine end date is calculated from the moment of isolation of the last patient and final disinfection, after which it continues for the maximum time of the incubation (hidden) period: with plague - 6 days, with cholera - 5 days.
The term quarantine is also often misused to refer to restrictive anti-epidemic measures in hospitals, kindergartens, etc. during the spread of influenza, measles, etc.
Observation - medical observation of healthy people isolated in specially adapted rooms who have been in contact with patients with quarantine infections (plague, cholera), or persons traveling outside the quarantine zone before the end of its period. If necessary, observation can be carried out for other infectious diseases. The duration of observation is determined by the maximum duration of the latent period of the disease, for which it is carried out.
6. Vaccination as a method of creating artificial active immunity
To increase the body's reactivity to infectious diseases, vaccinations (vaccination) of the population are important. Vaccination - the introduction of a vaccine into the body - a method used to create artificial active immunity.
Vaccines are preparations obtained from microbes, viruses and their metabolic products and used for active immunization of people and animals for preventive and therapeutic purposes. Vaccines are divided into live, killed, toxoids and chemical. For the preparation of live vaccines, strains of pathogenic microbes with weakened virulence are used, i.e. deprived of the ability to cause a disease, but retaining the ability to multiply in the body of the vaccinated and cause a benign vaccinal process (BCG - vaccine against tuberculosis, brucellosis vaccine, against viral hepatitis A, etc.). Live vaccines provide permanent immunity. The methods of administration of such vaccines are varied: subcutaneous (most vaccines), dermal or intradermal (tularemia vaccine, BCG, etc.), enteral (BCG), combined (BCG, against brucellosis).
Killed vaccines are obtained by heating bacteria and viruses, other physical influences (phenol, alcohol solutions, formalin). Killed vaccines are most often administered subcutaneously or intramuscularly (against intestinal infections, whooping cough, therapeutic vaccine against brucellosis). Chemical vaccines are prepared by extracting the main antigens with immunogenic properties from microbial bodies (polyvaccine is a complex preparation for immunization against typhoid fever, dysentery, cholera and tetanus, as well as an immunogen against dysentery).
Anatoxin is a neutralized toxin, which, however, can cause active toxoid immunity. An example is the diphtheria, tetanus and whooping cough vaccine (DTP - contains two toxoids and a killed whooping cough vaccine).
In addition to vaccines, immunoglobulins are used for specific emergency prevention and treatment. They contain antibodies in a concentrated form, which stimulate non-specific resistance of the body.
Antitoxic specific sera are obtained from the blood of horses, which are previously hyperimmunized with specific attenuated toxins.
The first vaccination is carried out in order to prevent infectious diseases and according to epidemic indications in the focus of an infectious disease. The adopted vaccination schedule begins at the maternity hospital. Newborns are given the BCG vaccine against tuberculosis, then revaccination is carried out: at 2 years, at 7 years and every 3-4 years until the age of 16. From the age of three months, the child is vaccinated with DTP three times, at intervals of 30-40 days, and then revaccinated after 6-9 months. The next stage is age-related revaccination every 3-4 years. For adults - DS every 5 years.
Of no small importance in the prevention of infectious diseases are vaccinations carried out according to epidemiological indications (against tetanus, cholera, plague, tick-borne encephalitis).
The result of artificial immunization depends not only on the quality of bacterial preparations, but also on the correct selection of population contingents to be vaccinated, on compliance with the timing of immunization and the dosage of the drug.
Main literature
1. Baran V.M., Klyuchareva A.A., Karpov I.A., Khamitskaya A.M. Infectious diseases with the basics of epidemiology: Uch. allowance for medical schools. - Minsk: "Universitetskaya", 1998.
2. Ten E.E. Fundamentals of medical knowledge: Textbook. - M.: Mastery, 2002.
additional literature
1. Laptev A.P., Minkh A.A. Hygiene of physical culture and sports: Textbook for institutes of physical culture and sports. - M .: "Physical culture and sport", 1979.
2. Tonkova-Yampolskaya R.V., Chertok T.Ya., Alferova I.N. Fundamentals of medical knowledge: Uch. allowance for pedagogical schools. - M.: Enlightenment, 1993.
3. Fundamentals of medical knowledge. / Ed. M.I. Gogolev: Prob. uch. allowance for avg. uch. manager - M.: Enlightenment, 1991.
4. Nurse's Handbook of Nursing. / Ed. N.R. Paleev. -M .: LLC "Firm Publishing House AST", 1999.
5. First aid. Complete guide. - M.: Eksmo Publishing House, 2003.
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