What is the name of the bacterium malaria. The development of the disease and characteristic changes in the body

Malaria(Italian mala aria - “bad air”, formerly known as “swamp fever”) - a group of transmissible infectious diseases transmitted to humans by the bites of mosquitoes of the genus Anopheles (“malarial mosquitoes”) and accompanied by fever, chills, splenomegaly (an increase in the size of the spleen) , hepatomegaly (enlargement of the liver), anemia. It is characterized by a chronic relapsing course. It is caused by parasitic protists of the genus Plasmodium (80-90% of cases - Plasmodium falciparum).

Malaria causes about 350-500 million infections and about 1.3-3 million deaths in humans every year. Sub-Saharan Africa accounts for 85-90% of these cases, with the vast majority affecting children under 5 years of age. The death rate is expected to double over the next 20 years.

The first chronicle evidence of a fever caused by malaria was found in China. They date back to around 2700 BC. e., during the Xia Dynasty.

What causes Malaria

The causative agents of malaria are the protozoa of the genus Plasmodium (Plasmodium). Four species of this genus are pathogenic for humans: P.vivax, P.ovale, P.malariae and P.falciparum In recent years, it has been established that a fifth species, Plasmodium knowlesi, also causes malaria in humans in Southeast Asia. A person becomes infected with them at the time of inoculation (injection) by a female malarial mosquito of one of the stages of the life cycle of the pathogen (the so-called sporozoites) into the blood or lymphatic system, which occurs during blood sucking.

After a short stay in the blood, the sporozoites of the malarial plasmodium penetrate into the hepatocytes of the liver, thereby giving rise to the preclinical hepatic (exoerythrocytic) stage of the disease. In a process of asexual reproduction called schizogony, from 2,000 to 40,000 hepatic merozoites, or schizonts, are eventually formed from one sporozoite. In most cases, these daughter merozoites re-enter the blood after 1-6 weeks. In infections caused by some North African strains of P. vivax, the primary release of merozoites from the liver into the blood occurs approximately 10 months after infection, coinciding with a short period of mass breeding of mosquitoes in the following year.

The erythrocyte, or clinical, stage of malaria begins with the attachment of merozoites that have entered the bloodstream to specific receptors on the surface of the erythrocyte membrane. These receptors, which serve as targets for infection, appear to be different for different species of malarial plasmodia.

Epidemiology of malaria
Under natural conditions, malaria is a naturally endemic, protozoal, anthroponotic, transmissible infection.

The causative agents of malaria find hosts in various representatives of the animal world (monkeys, rodents, etc.), but as a zoonotic infection, malaria is extremely rare.

There are three ways of contracting malaria: transmissible, parenteral (syringe, post-transfusion) and vertical (transplacental).

The main transmission route is transmissive. Human malaria vectors are female mosquitoes of the genus Anopheles. Males feed on the nectar of flowers.

The main vectors of malaria in Ukraine:
an. messae, An. maculipennis, An. atroparvus, An. Sacharovi, An. superpictus, An. pulcherrimus and others.

The life cycle of mosquitoes consists of a number of stages: egg - larva (I - IV age) - pupa - imago. Fertilized females attack a person in the evening or at night and feed on blood. In females that are not fed with blood, eggs do not develop. Blood-fed females remain in the dark corners of residential or utility rooms, thickets of vegetation until the end of the digestion of blood and the maturation of eggs. The higher the air temperature, the faster the development of eggs in the body of the female is completed - (gonotrophic cycle): at a temperature of + 30 ° C - up to 2 days, at + 15 ° C - up to 7 in P. vivax. Then they rush to the reservoir, where they lay their eggs. Such reservoirs are called anophelogenic.

The maturation of the aquatic stages of vector development also depends on temperature and lasts 2-4 weeks. At temperatures below +10°C, mosquitoes do not develop. During the warm season of the year, up to 3-4 generations of mosquitoes may appear in the middle latitudes, 6-8 in the south, and up to 10-12 in the tropics.

For sporogony, a temperature of at least + 16 ° C is required. Sporogony of P. vivax at +16°C is completed in 45 days, at +30°C - in 6.5 days. The minimum temperature for P. falciparum sporogony is +19 - 20°C, at which it is completed in 26 days, at +30°C - in 8 days.

The season for malaria transmission depends on this. In the tropics, the malaria transmission season reaches 8-10 months, in the countries of equatorial Africa it is year-round.

In temperate and subtropical climate zones, the malaria transmission season is limited to the summer-autumn months and lasts from 2 to 7 months.

In wintering mosquitoes, sporozoites die; therefore, females that hatch in the spring are not carriers of malarial plasmodia, and in each new season, mosquitoes are infected from malaria patients.

Perhaps intrauterine infection of the fetus through the placenta in the presence of infection in a pregnant mother, but more often this occurs during childbirth.

With these forms of infection, schizont malaria develops, in which there is no phase of tissue schizogony.

Susceptibility to malaria is universal. Only representatives of the Negroid race are immune to P. vivax.

The spread of malaria is determined by geographical, climatic and social factors. The boundaries of distribution are 60 - 64 ° north latitude and 30 ° south latitude. However, the species range of malaria is uneven. P. vivax, the causative agent of three-day malaria, has the widest range, the distribution of which is determined by geographic boundaries.

Tropical malaria has a smaller range because P. falciparum requires higher temperatures to develop. It is limited to 45° - 50° N. sh. and 20°S sh. Africa is the world's hotbed of tropical malaria.

The second place in distribution in Africa is occupied by four-day malaria, the range of which reaches 53 ° N. sh. and 29°S sh. and which has a focal, nesting character.

P. ovale is found mainly in the countries of West and Central Africa and on some islands of Oceania (New Guinea, Philippines, Thailand, etc.).

In Ukraine, malaria has been practically eliminated and mainly imported malaria and isolated cases of local infection are recorded - secondary from imported ones.

Malaria is imported to the territory of Ukraine from tropical countries and from neighboring countries - Azerbaijan and Tajikistan, where there are residual foci.

The largest part of imported cases is three-day malaria, which is the most dangerous due to possible transmission by mosquitoes sensitive to this type of pathogen. In second place is the importation of tropical malaria, the most severe clinically, but less dangerous epidemiologically, since Ukrainian mosquitoes are not sensitive to P. falciparum imported from Africa.

Cases of importation with an unidentified cause of infection are registered - “airport”, “baggage”, “accidental”, “transfusion” malaria.

The WHO European Office, due to the political and economic instability in the world, the growth of migration and the implementation of large-scale irrigation projects, highlights malaria as a priority problem due to the possibility of a return of the infection.

Under the influence of these factors, the formation of new foci of malaria, i.e., settlements with adjacent anophelogenic reservoirs, is possible.

In accordance with the WHO classification, 5 types of malaria foci are distinguished:
pseudo-focus - the presence of imported cases, but there are no conditions for the transmission of malaria;
potential - the presence of imported cases and there are conditions for the transmission of malaria;
active new - emergence of cases of local infection, transmission of malaria has occurred;
active persistent - the presence of cases of local infection for three years or more without interruption of transmission;
inactive - malaria transmission has ceased, there have been no cases of local infection during the last two years.

An indicator of the intensity of the risk of contracting malaria according to the WHO classification is the splenic index in children from 2 to 9 years old. According to this classification, 4 degrees of endemia are distinguished:
1. Hypoendemia - splenic index in children from 2 to 9 years old up to 10%.
2. Mesoendemia - splenic index in children from 2 to 9 years old is 11 - 50%.
3. Hyperendemia - the splenic index in children from 2 to 9 years old is above 50% and high in adults.
4. Holoendemia - the splenic index in children from 2 to 9 years old is constantly above 50%, the splenic index in adults is low (African type) or high (New Guinean type).

Pathogenesis (what happens?) during Malaria

According to the method of infection, sporozoite and schizont malaria are distinguished. Sporozoite infection- This is a natural infection through a mosquito, with the saliva of which sporozoites enter the human body. In this case, the pathogen passes through the tissue (in hepatocytes), and then the erythrocyte phase of schizogony.

Schizont malaria due to the introduction of ready-made schizonts into the human blood (hemotherapy, syringe malaria), therefore, unlike sporozoite infection, there is no tissue phase here, which determines the features of the clinic and treatment of this form of the disease.

The immediate cause of attacks of malarial fever is the entry into the blood during the breakdown of morula merozoites, which are a foreign protein, malarial pigment, hemoglobin, potassium salts, erythrocyte residues, which change the specific reactivity of the body and, acting on the heat-regulating center, cause a temperature reaction. The development of a fever attack in each case depends not only on the dose of the pathogen (“pyrogenic threshold”), but also on the reactivity of the human body. The alternation of fever attacks characteristic of malaria is due to the duration and cyclicity of the erythrocyte schizogony of the leading generation of plasmodia of one species or another.

Alien substances circulating in the blood irritate the reticular cells of the spleen and liver, cause their hyperplasia, and with a long course - the growth of connective tissue. Increased blood supply to these organs leads to their increase and soreness.

Important in the pathogenesis of malaria is the sensitization of the body by a foreign protein and the development of autoimmunopathological reactions. The breakdown of erythrocytes in erythrocyte schizogony, hemolysis as a result of the formation of autoantibodies, increased phagocytosis of erythrocytes of the reticuloendothelial system of the spleen are the cause of anemia.

Relapses are typical for malaria. The reason for the near relapses in the first 3 months after the end of the primary acute symptoms is the preservation of a part of erythrocyte schizonts, which, due to a decrease in immunity, begin to actively multiply again. Late or distant relapses, characteristic of three-day and oval malaria (after 6-14 months), are associated with the completion of the development of bradysporozoites.

Symptoms of Malaria

All clinical manifestations of malaria are associated only with erythrocyte schizogony.

There are 4 specific forms of malaria: three-day, oval-malaria, four-day and tropical.

Each species form has its own characteristics. However, fever attacks, splenohepatomegaly and anemia are typical for all.

Malaria is a polycyclic infection, in its course there are 4 periods: the period of incubation (primary latent), primary acute manifestations, secondary latent and relapse period. The duration of the incubation period depends on the type and strain of the pathogen. At the end of the incubation period, symptoms appear - precursors, prodromes: weakness, muscle, headache, chilling, etc. The second period is characterized by recurring attacks of fever, for which a staging development is typical - a change in the stages of chills, heat and sweat. During the chill, which lasts from 30 minutes. up to 2 - 3 hours, the body temperature rises, the patient cannot warm up, the extremities are cyanotic and cold, the pulse is rapid, breathing is shallow, blood pressure is elevated. By the end of this period, the patient warms up, the temperature reaches 39 - 41 ° C, a period of fever sets in: the face turns red, the skin becomes hot and dry, the patient is excited, restless, headache, delirium, confusion, sometimes convulsions. At the end of this period, the temperature drops rapidly, which is accompanied by profuse sweating. The patient calms down, falls asleep, a period of apyrexia begins. However, then the attacks are repeated with a certain cyclicity, depending on the type of pathogen. In some cases, the initial (initial) fever is irregular or permanent.

Against the background of attacks, the spleen and liver increase, anemia develops, all body systems suffer: cardiovascular (myocardial dystrophic disorders), nervous (neuralgia, neuritis, sweating, chilliness, migraine), genitourinary (symptoms of nephritis), hematopoietic (hypochromic anemia, leukopenia, neutropenia, lymphomonocytosis, thrombocytopenia), etc. After 10-12 or more attacks, the infection gradually subsides, and a secondary latent period sets in. With incorrect or ineffective treatment, a few weeks or months later, short-term (3 months), late or distant (6-9 months) relapses occur.

Three day malaria. The duration of the incubation period: minimum - 10 - 20 days, in case of infection with bradysporozoites - 6 - 12 months or more.

Characterized by prodromal phenomena at the end of incubation. A few days before the onset of attacks, chilling, headache, back pain, fatigue, nausea appear. The disease begins acutely. The first 5-7 days of fever may be of an irregular nature (initial), then an intermittent type of fever is established with a typical alternation of attacks every other day. For an attack, a clear change in the stages of chills, heat and sweat is characteristic. The heat period lasts 2-6 hours, less often 12 hours and is replaced by a period of sweating. Attacks usually occur in the morning. The spleen and liver after 2-3 temperature paroxysms increase, are sensitive to palpation. On the 2nd - 3rd week moderate anemia develops. This species form is characterized by near and distant relapses. The total duration of the disease is 2-3 years.

Malaria oval. In many clinical and pathogenetic features, it is similar to three-day malaria, but differs in a milder course. The minimum incubation period is 11 days, there may be a long incubation, as with a three-day incubation - 6 - 12 - 18 months; from publications, the deadline for incubation is 52 months.

Attacks of fever occur every other day and, unlike 3-day malaria, occur mainly in the evening. Early and distant relapses are possible. The duration of the disease is 3-4 years (in some cases up to 8 years).

tropical malaria. The minimum duration of the incubation period is 7 days, fluctuations up to 10 - 16 days. Characterized by prodromal phenomena at the end of the incubation period: malaise, fatigue, headache, joint pain, nausea, loss of appetite, feeling chilly. Initial fever is constant or irregular, initial fever. Patients with tropical malaria often lack typical malaria symptoms of an attack: no or mild chills, feverish period lasts up to 30-40 hours, temperature drops without sudden sweating, muscle and joint pains are pronounced. Cerebral phenomena are noted - headache, confusion, insomnia, convulsions, hepatitis with cholemia often develops, there are signs of respiratory pathology (phenomena of bronchitis, bronchopneumonia); quite often expressed abdominal syndrome (abdominal pain, nausea, vomiting, diarrhea); impaired renal function.

Such a variety of organ symptoms makes diagnosis difficult and is the cause of erroneous diagnoses.

Duration of tropical malaria from 6 months. up to 1 year.

malarial coma- cerebral pathology in tropical malaria is characterized by rapid, rapid, sometimes lightning-fast development and a difficult prognosis. Three periods are distinguished in its course: somnolence, sopor and deep coma, the lethality in which is close to 100%.

Often, cerebral pathology is aggravated by acute renal failure.

No less severe course is characterized by hemoglobinuric fever, pathogenetically associated with intravascular hemolysis. Most often, it develops in individuals with genetically determined enzymopenia (deficiency of the G-b-PD enzyme) while taking antimalarial drugs. May result in the death of the patient from anuria due to the development of acute renal failure.

The algid form of tropical malaria is less common and is characterized by a cholera-like course.

Mixed malaria.
In malaria-endemic areas, simultaneous infection by several species of Plasmodium occurs. This leads to an atypical course of the disease, making it difficult to diagnose.

Malaria in children.
In malaria-endemic countries, malaria is one of the causes of high child mortality.

Babies under 6 months of age born to immune women in these areas acquire passive immunity and very rarely get malaria. Most severely, often with a fatal outcome, children aged 6 months and older are ill. up to 4 - 5 years. Clinical manifestations in children of this age differ in originality. Often there is no most striking symptom - malarial paroxysm. At the same time, symptoms such as convulsions, vomiting, diarrhea, abdominal pain are observed, there are no chills at the beginning of the paroxysm and sweating at the end.

On the skin - rashes in the form of hemorrhages, spotty elements. Anemia is on the rise.

In older children, malaria usually proceeds in the same way as in adults.

Malaria in pregnancy.
Malaria infection has a very adverse effect on the course and outcome of pregnancy. It can cause abortions, premature births, eclampsia of pregnancy and death.

Vaccinated (schizontal) malaria.
This malaria can be caused by any human malaria pathogen, but P. malariae is the predominant species.

In past years, for the treatment of patients with schizophrenia, neurosyphilis, the method of pyrotherapy was used, infecting them with malaria by injecting the blood of a malarial patient. This is the so-called therapeutic malaria.

Currently, depending on the conditions of infection with plasmodia-infected blood, blood transfusion and syringe malaria are isolated. The literature describes cases of accidental malaria - professional infection of medical and laboratory personnel, as well as cases of infection of recipients of transplanted organs.

The viability of Plasmodium in the blood of donors at 4°C reaches 7-10 days.

It should be noted that post-transfusion malaria can also be severe, and in the absence of timely treatment, give an unfavorable outcome. It is difficult to diagnose it, primarily because the doctor does not have an assumption about the possibility of nosocomial infection with malaria.

The increase in cases of schizont malaria is currently associated with the spread of drug addiction.

In the treatment of such patients, there is no need to prescribe tissue schizontocides. One form of schizont malaria is a congenital infection, i.e., infection of the fetus during fetal development (transplacental if the placenta is damaged) or during childbirth.

Immunity against malaria.
In the process of evolution, humans have developed different mechanisms of resistance to malaria:
1. innate immunity associated with genetic factors;
2. acquired active;
3. acquired passive immunity.

Acquired active immunity caused by infection. It is associated with humoral restructuring, the production of antibodies, an increase in the level of serum immunoglobulins. Only a small part of the antibodies plays a protective role; in addition, antibodies are produced only against erythrocyte stages (WHO, 1977). Immunity is unstable, quickly disappears after the release of the body from the pathogen, has a species- and strain-specific character. One of the essential factors of immunity is phagocytosis.

Attempts to create artificial acquired active immunity through the use of vaccines do not lose their value. The possibility of creating immunity as a result of vaccination with attenuated sporozoites has been proven. Thus, immunization of people with irradiated sporozoites protected them from infection for 3-6 months. (D. Clyde, V. McCarthy, R. Miller, W. Woodward, 1975).

Attempts have been made to create merozoite and gamete antimalarial vaccines, as well as a synthetic multispecies vaccine proposed by Colombian immunologists (1987).

Complications of malaria: malarial coma, rupture of the spleen, hemoglobinuric fever.

Diagnosis of Malaria

Diagnosis of malaria is based on an analysis of the clinical manifestations of the disease, epidemiological and geographical history data and is confirmed by the results of a laboratory blood test.

The final diagnosis of the specific form of malaria infection is based on the results of a laboratory blood test.

With the study mode recommended by WHO for mass examinations, it is necessary to carefully examine 100 fields of view in a thick drop. Examination of two thick drops for 2.5 minutes. per each is more effective than examining one thick drop for 5 minutes. When Plasmodium malaria is detected in the very first fields of view, the viewing of preparations is not stopped until 100 fields of view are viewed so as not to miss a possible mixed infection.

If indirect signs of a malarial infection are detected in a patient (stay in the malarial zone, hypochromic anemia, the presence of pigmentophages in the blood - monocytes with clumps of almost black malarial pigment in the cytoplasm), it is necessary to examine a thick drop more carefully and not two, but a series of 4 - 6 at one prick. In addition, with a negative result in suspicious cases, it is recommended to take blood samples repeatedly (4-6 times a day) for 2-3 days.

The laboratory response indicates the Latin name of the pathogen, the generic name of Plasmodium is reduced to "P", the species name is not reduced, as well as the stage of development of the pathogen (required when P. falciparum is detected).

To control the effectiveness of treatment and identify possible resistance of the pathogen to the antimalarial drugs used, the number of Plasmodium is counted.

The detection of mature trophozoites and schizonts - morula in the peripheral blood in tropical malaria indicates a malignant course of the disease, which the laboratory must immediately inform the attending physician.

In practice, the former have found greater use. More often than other test systems, an indirect immunofluorescence reaction (IRIF) is used. As an antigen for the diagnosis of three-day and four-day malaria, smears and drops of blood with a large number of schizonts are used.

For the diagnosis of tropical malaria, the antigen is prepared from an in vitro culture of P. falciparum, since in most patients there are no schizonts in the peripheral blood. Therefore, for the diagnosis of tropical malaria, the French company BioMerieux produces a special commercial kit.

Difficulties in obtaining an antigen (a patient's blood product or from an in vitro culture), as well as insufficient sensitivity, make it difficult to introduce NRIF into practice.

New methods for diagnosing malaria have been developed on the basis of luminescent enzyme-linked immunosorbent sera, as well as using monoclonal antibodies.

Enzyme-linked immunosorbent assay using soluble antigens of Plasmodium malaria (REMA or ELISA), like RNIF, is mainly used for epidemiological studies.

Malaria Treatment

Quinine is still the most commonly used drug for treating malaria. It was replaced for a while by chloroquine, but more recently quinine has regained popularity. The reason for this was the appearance in Asia and then spread to Africa and other parts of the world, Plasmodium falciparum with a mutation of resistance to chloroquine.

Extracts of the plant Artemisia annua (Artemisia annua), which contain the substance artemisinin and its synthetic analogues, are highly effective, but their production is expensive. Currently (2006), clinical effects and the possibility of producing new drugs based on artemisinin are being studied. Another work by a team of French and South African researchers has developed a group of new drugs known as G25 and TE3 that have been successfully tested in primates.

Although antimalarial drugs are on the market, the disease poses a threat to people who live in endemic areas where there is no adequate access to effective drugs. According to Médecins Sans Frontières, the average cost of treating a person infected with malaria in some African countries is as low as US$0.25 to US$2.40.

Prevention of Malaria

Methods that are used to prevent the spread of the disease or for protection in areas endemic for malaria include preventive medicines, mosquito extermination, and mosquito bite prevention products. At the moment there is no vaccine against malaria, but active research is underway to create one.

Preventive medicines
A number of drugs used to treat malaria can also be used for prevention. Usually, these drugs are taken daily or weekly at a lower dose than for treatment. Preventive medicines are commonly used by people visiting areas at risk of contracting malaria and are hardly used by the local population due to the high cost and side effects of these medicines.

Since the beginning of the 17th century, quinine has been used for prevention. The 20th century synthesis of more effective alternatives such as quinacrine (Acriquine), chloroquine, and primaquine reduced the use of quinine. With the advent of the chloroquine-resistant strain of Plasmodium falciparum, quinine has returned as a treatment, but not a preventive.

Mosquito extermination
Efforts to control malaria by killing mosquitoes have been successful in some areas. Malaria was once common in the United States and Southern Europe, but the draining of swamps and improved sanitation, along with the control and treatment of infected people, have made these areas unsafe. For example, in 2002, there were 1,059 cases of malaria in the United States, including 8 deaths. On the other hand, malaria has not been eradicated in many parts of the world, especially in developing countries - the problem is most prevalent in Africa.

DDT has proven to be an effective chemical against mosquitoes. It was developed during World War II as the first modern insecticide. At first it was used to fight against malaria, and then it spread to agriculture. Over time, pest control, rather than mosquito eradication, has come to dominate the use of DDT, especially in developing countries. Throughout the 1960s, evidence of the negative effects of its misuse increased, eventually leading to the banning of DDT in many countries in the 1970s. Until that time, its widespread use had already led to the emergence of DDT-resistant mosquito populations in many areas. But now there is the prospect of a possible return of DDT. The World Health Organization (WHO) today recommends the use of DDT against malaria in endemic areas. Along with this, it is proposed to apply alternative insecticides in areas where mosquitoes are resistant to DDT in order to control the evolution of resistance.

Mosquito nets and repellents
Mosquito nets help keep people away from mosquitoes and thereby significantly reduce infections and transmission of malaria. Nets are not a perfect barrier, so they are often used in conjunction with an insecticide that is sprayed to kill mosquitoes before they can find their way through the net. Therefore, nets impregnated with insecticides are much more effective.

For personal protection, closed clothing and repellents are also effective. Repellents fall into two categories: natural and synthetic. Common natural repellents are the essential oils of certain plants.

Examples of synthetic repellents:
DEET (active substance - diethyltoluamide) (eng. DEET, N, N-diethyl-m-toluamine)
IR3535®
Bayrepel®
Permethrin

transgenic mosquitoes
Several variants of possible genetic modifications of the mosquito genome are considered. One potential mosquito control method is the rearing of sterile mosquitoes. Significant progress has now been made towards the development of a transgenic or genetically modified malaria-resistant mosquito. In 2002, two groups of researchers have already announced the development of the first samples of such mosquitoes.

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The fear of contracting an infectious disease is familiar to many travelers to tropical countries. It is in the warm regions that most of the pathogens of severe pathologies in the human body live. One such disease is tropical malaria.

What kind of disease is this, what are the causes and sequence of its occurrence, what are the symptoms and treatment, and how to help the body quickly get rid of a terrible disease - read in our publication.

Description of the infection

At the moment, science has established five types of plasmodia - the causative agents of this pathology.

The disease got its name from the Italian word malaria. In translation, malaria means bad, spoiled air. Another name for this disease is also known - swamp fever. This is because, along with hepatolienal syndrome (enlargement of the liver and spleen) and anemia (anemia), paroxysm of fever is considered the main symptom of malaria.

"Malarial fever causes 3 million deaths each year, of which one million are young children."

The main source of infection in malaria is the bite of a female malarial mosquito, since anopheles males feed on the nectar of flowers. Infection occurs when the causative agent strain of malaria enters the blood of a person:

• After being bitten by an Anophele mosquito.
• From mother to child during pregnancy and childbirth.
• Through the use of non-sterile medical instruments with remnants of infected blood cells.

People have been suffering from malaria since ancient times. The intermittent fever inherent in the disease is described in a Chinese chronicle dated to 2700 BC. e. The search for the root cause of malaria lasted for thousands of years, but the first success came to physicians in 1880, when the French physician Charles Laveran was able to detect plasmodia in the blood of an infected patient.

Malaria has been known since ancient times

Anopheles, to which the malarial mosquito belongs, live on almost all continents, with the exception of territories whose climate is too harsh - Antarctica, the Far North and Eastern Siberia.

However, only those members of the Anopheles genus that live in southern latitudes cause malaria, since the Plasmodium they carry can only survive in warm climates.

With the help of the image you will learn what a malaria mosquito looks like.

Mosquitoes are the main carrier of the disease.

"According to the WHO, 90% of infections have been reported in Africa."

Anopheles are blood-sucking insects. Therefore, malaria is considered a disease of transmissible etiology, that is, an infection that is transmitted by blood-sucking arthropods.

The life cycle of anopheles takes place near water bodies, where the mosquito lays eggs and larvae appear. For this reason, malaria is common in waterlogged and swampy areas. An increase in the incidence can be observed during periods of heavy rains that have replaced drought, as well as as a result of population migration from epidemiologically disadvantaged regions.

The degree of infection is determined by the number of bites of infectious mosquitoes per year. In the countries of Southeast Asia, this figure rarely reaches one, while residents of tropical Africa can be attacked by insect vectors more than 300 times a year.

The main distribution area of ​​the disease is tropical latitudes.

Like many infectious diseases, epidemics and acute outbreaks of malaria most often occur in endemic areas or in remote areas where people do not have access to essential medicines.

To reduce the incidence rate, modern epidemiology recommends vaccinating people living in swampy areas where the disease is usually common.

Varieties of pathology

The development of various forms of malaria is provoked by different types of plasmodia.

The most common and one of the most dangerous types of the disease is tropical malaria. It is distinguished by lightning-fast damage to internal organs, the rapid course of the disease, and a large number of severe complications. Often leads to death. Treatment of the infection is hampered by the resistance of the strain to most antimalarials. The causative agent is Plasmodium falciparum.

This type of infection is characterized by relapsing fever with significant daily temperature fluctuations, including a critical decrease in its indicators. Attacks are repeated at short intervals. The infection lasts for a year.

As a rule, with tropical malaria, cerebral, septic, algidic and renal forms of pathologies develop, as well as malarial coma, increased tendon reflexes and a coma.

Three-day malaria is the result of infection with a strain of Plasmodium vivax. Downstream, the three-day form of the pathology is similar to oval malaria caused by a strain of Plasmodium ovale, which is much less common. If malaria attacks are similar in symptoms, then the methods of its treatment are usually the same.

The incubation of strains that cause a three-day form of infection is short and long, depending on the variety of Plasmodium. The first signs of malaria of the three-day type can appear both after 14 days and after 14 months.

Its course is characterized by multiple relapses and the appearance of complications in the form of hepatitis or nephritis. Pathology responds well to treatment. The total duration of infection is 2 years.

The disease is characterized by the development of complications.

"Negroids have antimalarial immunity and are resistant to the Plasmodium vivax strain."

Four-day malaria (quartana) is a form of infection with a strain of Plasmodium malariae.

Malaria of the four-day type is characterized by a benign course, without enlargement of the spleen and liver and other pathological conditions that usually develop against the background of the disease. The main symptoms of quartana are quickly eliminated with medication, but it is difficult to completely get rid of malaria.

"Bouts of four-day malaria can recur even 10 to 20 years after its symptoms have been eliminated."

There are known cases of infection of people as a result of blood transfusions from donors who had previously had a four-day form of infection.

Another pathogen, a strain of Plasmodium knowlesi, has recently been discovered. It is known that this strain of Plasmodium causes the spread of malaria in Southeast Asia. So far, epidemiology does not have complete information about the features of this form of the disease.

All types of malaria differ in symptoms, course and prognosis of the disease.

The specifics of the development of infectious pathology

"Several thousand daughter cells can develop from a single sporozoite, enhancing the progress of the disease."

The subsequent stages in the development of the pathogen determine all the pathological processes that characterize the clinical picture of malaria.

• tissue schizogony.

The disease has several stages of development.

Moving along with the blood flow, Plasmodium penetrate into the hepatocytes of the liver and are divided into forms of rapid and slow development. Subsequently, chronic malaria arises from a slowly developing form, causing numerous relapses. After the liver cells are destroyed, the plasmodia enter the blood vessels and attack the red blood cells. At this stage, the clinical symptoms of malaria do not appear.

• Erythrocyte schizogony.

Having penetrated into erythrocytes, schizonts absorb hemoglobin and increase in size, which causes rupture of the erythrocyte and the release of malarial toxins and newly formed cells - merozoites into the blood. Each merozoite is again introduced into the erythrocyte, starting a repeated cycle of damage. At this stage of malaria, a characteristic clinical picture is manifested - fever, enlargement of the spleen and liver.

• Gametocytogonia.

The final stage of erythrocyte schizogony, which is characterized by the formation of plasmodium germ cells in the blood vessels of the internal organs of a person. The process is completed in the stomach of the mosquito, where the gametocytes enter with the blood after the bite.

The life cycle of Plasmodium, which causes the development of malaria, is presented in the video below.

The duration of the life cycle of plasmodia influences the incubation period of malaria.

Manifestations of symptoms

From the moment an infectious agent enters the human body to the stage when the pathological anatomy of malaria appears, a lot of time can pass.

Four-day malaria can appear within 25-42 days.

The pathogenesis of tropical malaria occurs relatively quickly - in 10-20 days.

Three-day malaria has an incubation period of 10 to 21 days. Infection, transmitted by slowly developing forms, becomes acute within 6-12 months.

Oval-malaria manifests itself in 11-16 days, when infected with slowly developing forms - from 6 to 18 months.

Depending on the period of development of the disease, the symptoms of malaria differ in the intensity and nature of the manifestations.

• prodromal period.

The first signs of the disease are nonspecific and look more like a viral infection than a serious illness like malaria. The malaise is accompanied by headaches, deterioration of health, weakness and fatigue, periodically manifested by pain in the muscles and a feeling of discomfort in the abdomen. The average duration of the period is 3-4 days.

• period of primary symptoms.

Occurs when a fever occurs. The paroxysm characteristic of the acute period appears in the form of successive stages - chills with an increase in temperature from 39 ° C and a duration of up to 4 hours, fever with an increase in temperature to 41 ° C and a duration of up to 12 hours, increased sweating, lowering the temperature to 35 ° C.

• Intercritical period.

During it, the body temperature normalizes and the well-being improves.

Symptoms of the disease depend on the stage.

In addition, there are such consequences of malaria as yellowness of the skin, confusion, drowsiness or insomnia, anemia.

Features of pathological changes

Depending on the type of disease, malarial paroxysm is determined by specific characteristics. The definition of three-day malaria involves a short morning attack that appears every other day. The duration of the attack is up to 8 hours.

The four-day form is characterized by a recurrence of attacks every two days.

During the tropical form of the disease, short interictal periods (3-4 hours) are observed, and the temperature curve is characterized by the predominance of heat for 40 hours. Often the body of patients can not withstand such a load, which leads to death.

With a long course of the disease, the plasmoid pigment is absorbed by the internal organs.

It is possible to detect complications of malaria in the form of an increase in organs in children a few days after the onset of the disease with the help of palpation. Children, unlike adults, are not protected by immunity that can resist infection.

In the tropical form of infection, pathological anatomy is observed in the brain, pancreatic and intestinal mucosa, heart and subcutaneous tissue, in the tissues of which stasis is formed. If a patient has been in a malarial coma for more than a day, petechial hemorrhage and necrobiosis in certain parts of the brain are possible.

The pathomorphology of three-day and four-day malaria is practically the same.

Elimination of the consequences of infection

To diagnose an infectious lesion in medicine, a complete blood count, urinalysis, biochemical analysis, as well as clinical, epidemic, anamnestic criteria and laboratory results are used.

Differential diagnostic testing of patients' blood smears for malaria and possible complications is indicated for all patients with febrile symptoms. The procedure is prescribed before the start of treatment.

Often, donors - carriers of pathogens transmitted through the blood - become the source of infection.

As soon as the diagnosis is confirmed, the patient is hospitalized in an infectious diseases hospital and treatment is prescribed.

The aims and objectives of treatment measures are summarized in the form of a short guide:

Treatment has a number of main directions.

• The vital activity of the causative agent of the disease in the patient's body must be interrupted.
• The development of complications should be prevented.
• Do everything to save the life of the patient.
• To ensure the prevention of the development of a chronic form of pathology and the appearance of relapses.
• Prevent the spread of the infectious agent.
• Prevent Plasmodium from developing resistance to antimalarial drugs.

The basis of medical care for the patient is preparations of hematoschizotropic (Hingamin, Delagil, Chloridine) and gametocidal action (Delagil). In the acute course of the disease, the patient is provided with complete rest, plenty of fluids, and protection from hypothermia. In addition, a diet is recommended, aimed at increasing immunity and general strengthening of the patient's body, and folk remedies for malaria.

Even a strong and healthy man finds it difficult to cope with the infection on his own. Without the help of professional doctors, the disease can cause such severe complications as malarial coma, the development of hemorrhagic and convulsive syndrome, malarial algid, cerebral edema, renal failure, urinary retention, the appearance of a hemorrhagic rash, DIC, etc.

The fight against malaria involves measures to prevent the disease - protection from mosquito bites, vaccination and antimalarial drugs.

The disease is very insidious. It must be treated under constant medical supervision. At home, it is impossible to achieve the desired effect; at best, it will be possible to remove the symptoms of the disease. However, this is not enough - to avoid relapse, you need long-term adequate treatment.

Accompanied by fever, chills, enlargement of the spleen and liver, anemia. A characteristic feature of this protozoal invasion is the cyclical clinical course, i.e. periods of improvement in well-being are replaced by periods of sharp deterioration with a high rise in temperature.

The disease is most common in countries with a hot climate. These are South America, Asia and Africa. According to the World Health Organization, malaria is a serious health problem in 82 countries where the death rate from this infection is very high.

The relevance of malaria for a Russian person is due to the possibility of infection during tourist trips. Often, the first symptoms appear already upon arrival at home, when a person has a fever.

Without fail, when this symptom appears, you should inform the doctor about your trip, because. this will facilitate the establishment of the correct diagnosis and save time.

Causes, clinic of the disease

The causative agent of malaria is the malarial Plasmodium. It belongs to the class of the simplest. Causative agents can be 4 types of plasmodia (although there are more than 60 species in nature):

• R. Malariae - leads to malaria with a 4-day cycle;
• R. vivax - causes malaria with a 3-day cycle;
• R. falciparum - causes tropical malaria;
• R. Ovale - causes an oval-shaped three-day malaria.

The life cycle of malarial plasmodia includes a successive change of several stages. In this case, there is a change of owners. At the stage of schizogony, pathogens are found in the human body. This is the stage of asexual development, it is replaced by the stage of sporogony.

It is characterized by sexual development and occurs in the body of the female mosquito, which is the carrier of the infection. Causal mosquitoes belong to the genus Anopheles.

The penetration of malarial plasmodia into the human body can occur at different stages in different ways:

1. When bitten by a mosquito, infection occurs at the sporozontal stage. In 15-45 minutes, the penetrated plasmodia find themselves in the liver, where their intensive reproduction begins.
2. The penetration of erythrocyte cycle plasmodia at the schizont stage occurs directly into the blood, bypassing the liver. This path is realized by the introduction of donor blood or by using non-sterile syringes that can be infected with Plasmodium. At this stage of development, it penetrates from the mother to the child in utero (vertical route of infection). This is the danger of malaria for pregnant women.

In typical cases, the division of Plasmodium that enters the body with a mosquito bite occurs in the liver. Their number is multiplying. At this time, there are no clinical manifestations (incubation period).

The duration of this stage varies depending on the type of pathogen. It is minimal in P. Falciparum (from 6 to 8 days) and maximal in P. malariae (14-16 days).

The characteristic symptoms of malaria are described by the well-known triad:

• paroxysmal (like crises) fever, recurring at regular intervals (3 or 4 days);
• enlargement of the liver and spleen (hepatomegaly and splenomegaly, respectively);
• anemia.

The first symptoms of malaria are nonspecific. They correspond to the prodromal period and are manifested by signs characteristic of any infectious process:

• general malaise;
• severe weakness;
• lower back pain;
• joint and muscle pain;
• a slight increase in temperature;
• decreased appetite;
• dizziness;
• headache.

A specific increase in temperature develops due to the release of plasmodia into the blood. This process is repeated many times, being reflected in the temperature curve. The cycle time is different - in some cases it is 3 days, and in others - 4.

Based on this, the corresponding varieties of malaria (three-day and four-day) are distinguished. This is the period of obvious clinical manifestations, when the patient goes to the doctor.

The fever in malaria has a characteristic appearance due to the successive change of three phases. In the beginning, the stage of chills (a person cannot warm up, despite warm wrappings), which is replaced by fever (second stage). The temperature rises to high values ​​(40-41°C).

The attack ends with excessive sweating. It usually lasts from 6 to 10 hours. After an attack, a person immediately falls asleep due to a pronounced weakening that has developed as a result of intoxication and muscle contractions.

An increase in the liver and spleen is not determined from the very beginning of the disease. These symptoms can be detected after 2-3 febrile attacks. Their appearance is due to the active reproduction of malarial plasmodia in the liver and spleen.

When infected, anemia immediately appears in the blood, associated with the destruction of red blood cells (malarial plasmodia settle in them).

At the same time, the level of leukocytes, mainly neutrophils, decreases. Other hematological signs are accelerated erythrocyte sedimentation rate, complete absence of eosinophils, and a relative increase in lymphocytes.

These signs indicate the activation of the immune system. She fights the infection, but she can't cope. The disease progresses, and the risk of complications increases.

With a certain degree of probability, they can be predicted on the basis of unfavorable prognostic signs. These are considered:

• fever observed every day, and not cyclically (after 3-4 days);
• the absence of an inter-fever period between attacks (an elevated temperature is constantly determined, which between attacks corresponds to subfebrile values);
• severe headache;
• widespread convulsions observed 24-48 hours after the next attack;
• a critical decrease in blood pressure (70/50 mm Hg or less), approaching a state of shock;
• high level of protozoa in the blood according to microscopic examination;
• the presence of plasmodia in the blood, which are at different stages of development;
• progressive increase in the number of leukocytes;
• decrease in glucose below the value of 2.1 mmol / l.

Main complications malaria are:

• malarial coma, which is more common in pregnant women, children and young people;
• acute kidney failure with a decrease in diuresis less than 400 ml per day;
• hemoglobinuric fever, which develops with massive intravascular destruction of red blood cells and the formation of a large amount of toxic substances;
• malarial algid, which resembles brain damage in this disease, but differs from it in the preservation of consciousness;
• pulmonary edema with acute onset and course (often fatal);
• rupture of the spleen associated with torsion of its legs or congestion;
• severe anemia due to hemolysis;
• intravascular coagulation within the framework of DIC, followed by pathological bleeding.

Tropical malaria complications may be specific:

• corneal damage;
• clouding of the vitreous body;
• choroiditis (inflammatory damage to the capillaries of the eye);
• visual neuritis;
• paralysis of the eye muscles.

Laboratory diagnosis of malaria is carried out according to indications. These include:

1) Any increase in body temperature in a person located in an endemic geographical area (countries with increased incidence).

2) An increase in temperature in a person who has had a blood transfusion in the last 3 months.

3) Repeated episodes of fever in a person receiving therapy in accordance with the final diagnosis (an established diagnosis is any disease other than malaria).

4) Preservation of fever for 3 days during the epidemic period and more than 5 days at other times.

5) Presence of certain symptoms (one or more) in people who have visited endemic countries in the last 3 years:

• fever;
• malaise;
• chills;
• liver enlargement;
• headache;
• enlargement of the spleen;
• decrease in hemoglobin;
• yellowness of the skin and mucous membranes;
• the presence of herpetic eruptions.

To verify the diagnosis, various methods of laboratory examination can be used:

1. Microscopic study of blood smears (allows you to directly detect malarial plasmodium).
2. Express test.
3. (the study of genetic material by repeatedly obtaining copies of the DNA of the malarial plasmodium in its presence in the blood).
4. Biochemical analysis is performed to determine the severity of the disease (determines the severity of liver damage, which is always observed with malaria).

All patients with a confirmed diagnosis of malaria are shown to undergo a number of instrumental studies. Their results help the doctor to identify possible complications and start their treatment in time.

• ultrasound scanning of the abdominal cavity (special attention is paid to the size of the liver, kidneys and spleen);
• electrocardiogram;
• radiography of the lungs;
• echocardioscopy;
• neurosonography;
• electroencephalography.

Treatment of patients with malaria is carried out only in a hospital. The main goals of therapy are:

• prevention and elimination of acute attacks of the disease;
• prevention of complications and their timely correction;
• prevention of recurrence and carriage of malarial plasmodia.

All patients immediately after the diagnosis is recommended bed rest and the appointment of antimalarial drugs. These include:

• Primakhin;
• Chloroquine;
• Mefloquine;
• Pyrimethamine and others.

At the same time, the use of antipyretic and symptomatic drugs is indicated. They are quite diverse due to the multiorganism of the lesion. Therefore, doctors of various specialties, and not only infectious disease specialists, are often involved in the treatment.

In cases where this does not happen, a change in the antimalarial drug is required. It is also indicated when, on the 4th day, plasmodia are found in the blood. This may indicate possible pharmacological resistance. It increases the risk of distant relapses.
If everything goes smoothly, then special criteria are determined to finally confirm the cure. These include:

• temperature normalization;
• reduction of the spleen and liver to normal size;
• normal blood picture - the absence of asexual stages of malarial plasmodia in it;
• normal indicators of a biochemical blood test, indicating the restoration of liver function.

Prevention of malaria

Map of the distribution of malaria in the world

Tourists should pay close attention to the prevention of malaria. Even before traveling, you should find out with a travel agency whether the country poses a risk for this disease.

If yes, then you should visit an infectious disease specialist in advance. He will recommend taking antimalarial drugs that will protect the person from infection.

There is no specific vaccine for malaria.

• avoid being on the street after 17.00, because at this time there is a peak of mosquito activity;
• if necessary, go outside - cover the body with clothes. Pay special attention to the ankles, where mosquitoes most often bite, as well as the wrists and hands, where the skin is very thin;
• the use of repellents.

If the child is small, then parents should refrain from traveling to dangerous countries. In childhood, taking antimalarial drugs is not desirable, due to the frequent development of side effects and hepatotoxicity. Therefore, parents should weigh the possible risks.

world malaria day

The World Health Organization established International Malaria Day in 2007 (at its 60th session). It falls on April 25th.

The prerequisite for establishing the date was disappointing statistics. Thus, a new infection occurs annually in 350 - 500 million cases. Of these, death occurs in 1-3 million people.

The main objective of World Malaria Day is to promote preventive measures against the disease.

Malaria is a disease of the African continent, South America and Southeast Asia. Most of the cases of infection are recorded in young children living in West and Central Africa. In these countries, malaria leads among all infectious pathologies and is the main cause of disability and death of the population.

Etiology

Malaria mosquitoes are ubiquitous. They breed in stagnant, well-heated water bodies, where favorable conditions are preserved - high humidity and high air temperature. That is why malaria used to be called "swamp fever". Malaria mosquitoes are outwardly different from other mosquitoes: they are slightly larger, have darker colors and transverse white stripes on their legs. Their bites also differ from ordinary mosquitoes: malarial mosquitoes bite more painfully, the bitten place swells and itches.

Pathogenesis

In the development of plasmodium, 2 phases are distinguished: sporogony in the mosquito body and schizogony in the human body.

In more rare cases, there is:

1. Transplacental route - from a sick mother to a child,
2. Hemotransfusion route - during blood transfusion,
3. Infection through contaminated medical instruments.

The infection is characterized by high susceptibility. Residents of the equatorial and subequatorial zones are most susceptible to malaria infection. Malaria is the leading cause of death for young children living in endemic regions.

malaria distribution regions

The incidence is usually recorded in the autumn-summer period, and in hot countries - during the year. This is anthroponosis: only humans get malaria.

Immunity after an infection is unstable, type-specific.

Clinic

Malaria has an acute onset and presents with fever, chills, malaise, weakness, and headache. rises suddenly, the patient shakes. In the future, dyspeptic and pain syndromes are added, which are manifested by muscle and joint pain, nausea, vomiting, diarrhea, hepatosplenomegaly, and convulsions.

Types of malaria

Three-day malaria is characterized by a paroxysmal course. The attack lasts 10-12 hours and is conventionally divided into 3 stages: chills, fever and apyrexia.

In the interictal period, body temperature returns to normal, patients experience fatigue, fatigue, weakness. The spleen and liver thicken, the skin and sclera become subicteric. In the general blood test, erythropenia, anemia, leukopenia, and thrombocytopenia are detected. Against the background of attacks of malaria, all body systems suffer: sexual, excretory, hematopoietic.

The disease is characterized by a long benign course, attacks are repeated every other day.

In children, malaria is very severe. The clinic of pathology in children under the age of 5 years is distinguished by its originality. There are atypical attacks of fever without chills and sweating. The child turns pale, his limbs become cold, general cyanosis, convulsions, and vomiting appear. At the beginning of the disease, the body temperature reaches high numbers, and then persistent low-grade fever persists. Intoxication is often accompanied by severe dyspepsia: diarrhea, abdominal pain. Affected children develop anemia and hepatosplenomegaly, and a hemorrhagic or patchy rash appears on the skin.

Tropical malaria is much more severe. The disease is characterized by less pronounced chills and sweating, but more prolonged attacks of fever with an irregular febrile curve. During the fall in body temperature, chilling reappears, a second rise and a critical decline. Against the background of severe intoxication, patients develop cerebral signs - headache, confusion, convulsions, insomnia, delirium, malarial coma, collapse. Perhaps the development of toxic hepatitis, respiratory and renal pathology with the corresponding symptoms. In children, malaria has all the characteristic features: febrile paroxysms, a special nature of fever, hepatosplenomegaly.

Diagnostics

Diagnosis of malaria is based on a characteristic clinical picture and epidemiological data.

Laboratory research methods occupy a leading place in the diagnosis of malaria. Microscopic examination of the patient's blood allows you to determine the number of microbes, as well as their genus and type. For this, two types of smear are prepared - thin and thick. The study of a thick drop of blood is carried out if malaria is suspected, to identify Plasmodium and determine its sensitivity to antimalarial drugs. To determine the type of pathogen and the stage of its development allows the study of a thin drop of blood.

In the general analysis of blood in patients with malaria, hypochromic anemia, leukocytosis, and thrombocytopenia are detected; in the general analysis of urine - hemoglobinuria, hematuria.

PCR is a fast, reliable and reliable laboratory diagnostic method for malaria. This expensive method is not used for screening, but only as an addition to the main diagnosis.

Serodiagnosis is of secondary importance. Enzyme immunoassay is carried out, during which the presence of specific antibodies in the patient's blood is determined.

Treatment

All patients with malaria are hospitalized in an infectious disease hospital.

Etiotropic treatment of malaria: "Hingamine", "Quinine", "Chloridine", "Chloroquine", "Akrikhin", sulfonamides, antibiotics - "Tetracycline", "Doxycycline".

In addition to etiotropic therapy, symptomatic and pathogenetic treatment is carried out, including detoxification measures, restoration of microcirculation, decongestant therapy, and the fight against hypoxia.

Colloidal, crystalloid, complex saline solutions are administered intravenously,"Reopoliglyukin", isotonic saline solution, "Hemodez". Patients are prescribed "Furosemide", "Mannitol", "Eufillin", carry out oxygen therapy, hemosorption, hemodialysis.

For the treatment of complications of malaria, glucocorticosteroids are used - intravenously "Prednisolone", "Dexamethasone". According to the indications, plasma or erythrocyte mass is transfused.

Patients with malaria should strengthen the immune system. It is recommended to add nuts, dried fruits, oranges, lemons to the daily diet. It is necessary during the illness to exclude the use of "heavy" food, and it is better to give preference to soups, vegetable salads, cereals. You should drink as much water as possible. It lowers body temperature and removes toxins from the patient's body.

Persons who have had malaria are registered with an infectious disease doctor and undergo periodic examinations for plasmodium carriage for 2 years.

Folk remedies will help speed up the healing process:

Timely diagnosis and specific therapy shorten the duration of the disease and prevent the development of severe complications.

Prevention

Preventive measures include the timely detection and treatment of patients with malaria and carriers of malarial plasmodium, epidemiological surveillance of endemic regions, the destruction of mosquitoes and the use of remedies for their bites.

There is currently no vaccine for malaria. Specific prevention of malaria is the use of antimalarial drugs. Persons traveling to endemic areas should undergo a course of chemoprophylaxis with Khingamine, Amodiakhin, Chloridine. For maximum effectiveness, these drugs are recommended to alternate every month.

Using natural or synthetic repellents, you can protect yourself from mosquito bites. They are collective and individual and are available in the form of a spray, cream, gel, pencils, candles and spirals.

Mosquitoes are afraid of the smell of tomatoes, valerian, tobacco, basil oil, anise, cedar and eucalyptus. A couple of drops of essential oil are added to vegetable oil and applied to exposed areas of the body.

Video: life cycle of malarial plasmodium

It is believed that malaria has accompanied mankind for over 50,000 years. The disease originated from Africa, namely the belts with a tropical and subtropical climate.

causative agents of malaria

Malaria is caused by protozoan unicellular microorganisms that belong to the genus Plasmodium. To date, 4 species of Plasmodium have been studied, which cause various forms of malaria in humans:

• Plasmodium falciparum is the most common causative agent, which is detected in 80% of cases (tropical malaria).
• Plasmodium malariae - causes the classic course of malaria (three-day malaria).
• Plasmodium vivax (four-day malaria).
• Plasmodium malaria-oval).

Plasmodium vivax and ovale have certain features of the life cycle, they can persist in the liver for a long time and lead to an exacerbation of the disease (relapse) after a significant period of time after infection (months and years later).

Recently, another type of malaria pathogen, Plasmodium knowlesi, has been discovered.

Features of infection with plasmodia

This infectious disease is anthroponotic. This means that the source of the pathogen is only a sick person, in whose blood there are sexually mature forms of plasmodia - gametocytes. Pathogen vector (a female mosquito of the genus Anopheles or "malarial mosquito") after being bitten by a sick person becomes infected with Plasmodium. After a certain period of time, during which plasmodia accumulate in the structures of the digestive tract of an infected mosquito, it becomes infectious for another person; when bitten, microorganisms enter the bloodstream, leading to the subsequent development of the disease.

Spread of disease

Malaria mosquitoes live in almost all climatic zones, with the exception of the arctic and subarctic. However, for the transfer of Plasmodium requires a certain high humidity and warm temperatures, so the incidence is higher in regions with tropical and subtropical climates. In Russia, sporadic (single) cases are recorded in the Transcaucasus, Central Asia, and the Caucasus.

In recent years, cases of malaria have been reported in the Moscow region and the Volga region.

The mechanism of the development of the disease

The main characteristic feature of the pathogenesis of malaria is the cyclicity of the disease associated with the properties of plasmodia. After being bitten by a mosquito and entering the human body, plasmodia penetrate into the erythrocytes (erythrocyte schizogony), where they accumulate, after which they enter the blood in large quantities. In the free state in the blood, a significant part of the plasmodium dies due to the protective effect of the immune system. This leads to severe intoxication of the body (accompanied by fever), caused by a significant amount of foreign protein. The rest of the microorganisms again enter the erythrocytes, where for a certain period of time (for each type of plasmodia it has its own) the pathogen accumulates (during this period of time, the person feels relatively normal). Then the accumulated cells of the causative agent of malaria enter the blood again, leading to intoxication (repeated cycle). With sufficient activity of the immune system, its cells begin to produce antibodies and other protective factors, which gradually completely destroy pathogens.

Some types of Plasmodium are able to pass into the tissue phase (usually they accumulate in hepatocyte liver cells) and do not manifest themselves for a long time. Under the influence of various reasons, they leave the tissues into the blood, penetrate into the erythrocytes and lead to an exacerbation of the disease in the form of intoxication.

Symptoms of malaria

Features of the clinical manifestations of malaria are associated with cyclic erythrocyte schizogony of plasmodium. Regardless of the form of the course of the disease and the type of pathogen, malaria is characterized by several periods:

Since this disease is cyclic, the attack and the interictal period alternate with each other (the cycle depends on the type of plasmodium). If left untreated, each subsequent attack is characterized by a more severe course and can lead to death. For each type of malaria, clinical symptoms have their own characteristics:

• Three-day malaria - characterized by bouts of fever every other day, the attack itself lasts from 6 to 12 hours, usually in the morning, then is replaced by profuse sweating and normalization of temperature. A few weeks after the onset of the disease, moderate anemia develops. The duration of the disease can reach 3 years.
• Four-day malaria - differs in that an attack of fever develops with an interval of 2 days, has a more benign, but long (up to 50 years) course.
• Malaria oval - has similarities with three-day malaria, attacks develop every other day, but mainly in the evening.
• Tropical malaria is a severe form of the disease with an attack of fever up to 30 hours, while there may not be a clear cyclical development of attacks. Against the background of an attack of fever, the central nervous system can be affected with the development of a malarial coma (prolonged lack of consciousness).

Tropical malaria develops in persons visiting regions with frequent registration of this disease (endemic zone of pathogen circulation and high incidence) without immunity. Also in endemic areas, a mixed variant may occur when infection occurs with several pathogens at once.

Diagnostics

The detection of the disease, as well as the diagnosis, is performed on the basis of a clinical examination (analysis of symptoms by an infectious disease doctor), as well as an additional study. Laboratory diagnosis of malaria includes several methods:

The choice of research methodology is determined by the capabilities of the medical institution, but it must necessarily include blood microscopy, especially at the height of a fever attack.

Treatment

Modern medicine for the successful treatment of malaria, aimed at the destruction of plasmodia, uses quinine. This is due to the fact that Plasmodium (especially the causative agent of tropical malaria) has developed resistance to more modern and less toxic drugs. The duration of the drug is determined by the severity of the infection, as well as repeated laboratory tests.

People with sickle cell anemia (an inherited disorder characterized by changes in the structure of hemoglobin and the shape of red blood cells) are completely immune to malaria.

Prevention of malaria

Modern malaria prevention includes specific and non-specific measures. Specific prophylaxis is aimed at creating immunity (immunity) in humans to malarial plasmodium. For this, a malaria vaccination is used, which is carried out for people living in endemic regions, as well as for those who plan to go there. Non-specific prophylaxis is aimed at the destruction of mosquitoes (draining the swamps where the mosquito larvae develop), the use of repellents (mosquito repellents), as well as mosquito nets on the windows of the premises.