Zika virus: symptoms, transmission routes, diagnosis and treatment. Basic diagnostic methods

website- The disease got its name from the place where the first carrier of the virus was found, the monkey was caught in the Zika forest, literally translated in “forest thickets”.

The disease is common in tropical and subtropical climates; since the end of 2015, the Zika virus has been in full swing in Brazil. Official WHO sources report more than 4 million cases of Zika infection worldwide.

The virus enters the bloodstream to humans through the bite of mosquitoes belonging to the genus Aedes. For several days, infected people experience a high body temperature, characteristic skin rash, redness of the conjunctiva and sclera of the eyes.

The Zika virus strain was first discovered in Uganda, on the African continent, during scientific research into the spread of the yellow fever virus. It was discovered in the blood of macaques in 1947, further studies showed its presence in the body of the inhabitants of the country.

It has been established that the Zika virus can also be transmitted from person to person through sexual contact, and from mother to child during fetal development.

About incubation period little is known about the disease, with a high degree of probability it can be from 1 to 3 days. Symptoms are mild and similar to other infectious diseases. The course of infection is always acute, chronic form disease is not accepted. It passes quickly enough, but the virus is able to influence the gene structure human body and cause rare but dangerous complications.

Clinical symptoms Zika virus infections include:

• minor headaches;
• general malaise;
• itchy macular or papular rash on the skin (the rash first appears on the face and then spreads throughout the body);
• fever
• pain in muscles and joints with possible swelling of small joints;
• hyperemia and inflammation of the conjunctiva (conjunctivitis);
• pain in the orbits of the eyes;
• intolerance to bright light.

If the disease is carried by a pregnant woman, then due to the penetration of the Zika virus into the body developing fetus, develop malformations of its development, which include microcephaly - a child is born with a reduced brain mass and a reduced skull. This condition is accompanied by a lag of the child in mental development followed by imbecility or idiocy. In adults, after infection, there were registered isolated cases development of the Guienne-Barré syndrome, which consists in the formation of an autoimmune process with a pronounced muscle weakness(myasthenia gravis). Usually, the symptoms of this syndrome disappear on their own without residual effects.

There is no specific etiotropic therapy (treatment aimed at destroying the causative agent of the pathological process) for Zika fever.

Treatment consists of bed rest, increased use liquids to reduce the level of intoxication, as well as the intake of easily digestible food with vitamins. To reduce body temperature at the height of fever and severity pain non-steroidal anti-inflammatory drugs (acetylsalicylic acid, ibuprofen, paracetamol) can be used in the joints after excluding the development of dengue fever, in which there is a risk of bleeding different localization. Usually, after following the general recommendations, after a few days, the manifestations of Zika fever decrease, and disappear on the 7-8th day from the onset of the disease.

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Zika fever is a rapidly spreading acute zooanthroponotic arbovirus infectious disease with a transmissible pathogen transmission mechanism. Distributed in tropical and subtropical countries. Currently, the disease is little studied.

The causative agent of the disease is the Zika virus (English Zika virus, ZIKV), belonging to the arboviruses of the family Flaviviridae kind Flavivirus. It should be noted that flaviviruses are the causative agents of a number of infectious diseases: yellow fever, dengue fever, tick-borne encephalitis, Omsk hemorrhagic fever, Powassan encephalitis, Japanese encephalitis, St. Louis encephalitis, Murray Valley encephalitis, and West Nile fever.

The structure of the virus is similar to that of other flaviviruses, it has a spherical nucleocapsid with a diameter of about 50 nm with a membrane, which is a glycoprotein shell, the surface proteins of which are arranged in ixoahedral symmetry. Inside the nucleocapsid is a single-stranded linear RNA containing 10,794 nucleotides encoding 3,419 amino acids that make up the protein structures of the virus. Attachment of the virus to cytoplasmic cell membranes and its penetration into the cell is due to the presence of a special membrane protein E (Fig. 1).

Viral RNA replication occurs on the surface of the endoplasmic reticulum in the cytoplasm of target cells. To synthesize its own polyprotein, the virus uses the proteins of host cells infected by it. Further, in the process of RNA replication into cellular mRNA, the synthesis of its own structural and non-structural nucleoproteins, the assembly of the viral cell, and the release of the virus through lysis of the host cell are performed.

It should also be noted high ability flaviviruses to mutations due to the imperfection of the mechanism of copying genetic information, which can lead to a change in the antigenic properties and virulence of the virus.

The virus was first isolated from rhesus monkeys (lat. Macaca mulatta) April 18, 1947 in the course of monitoring the forest form of yellow fever in the Zika forest (Uganda), as part of the Rockefeller research program, from where the name of the pathogen originates. Two days later, the febrile monkeys were taken to the laboratory, where mice were infected with their serum. After 10 days, all mice showed symptoms of the disease. Subsequently, the pathogen was isolated from the brain of infected animals. In 1948, the virus was first isolated from the body of a female mosquito of the genus Aedes aegipti, and in 1968 - from the biomaterials of representatives of the indigenous population of Nigeria. From 1951 to 1981, sporadic cases of the disease were recorded in Africa - in Uganda, Tanzania, Egypt, the Central African Republic, Sierra Leone, Gabon, Senegal, and also in some Asian countries, including India, Malaysia, the Philippines, Thailand, Vietnam and Indonesia. In April 2007, an outbreak of Zika fever with laboratory-confirmed cases of the disease was recorded on the Yap Islands in the Federal States of Micronesia for the first time (Zika virus RNA was isolated in biomaterials from patients in the acute phase of the disease). In 2013, an outbreak in French Polynesia. In 2015, the active spread of the virus began in Central and South America.

According to World Organization public health, the Zika virus is now prevalent in tropical areas with large mosquito populations. It is known to circulate in Africa, South and Central America, South Asia and western Pacific Ocean. Imported cases have been registered in Austria, Germany, Denmark, Ireland, Spain, Italy, Portugal, Finland and Switzerland, as well as in Israel and Australia. All cases returned from regions endemic for Zika fever (Fig. 2).



The source of the pathogen is sick people, healthy virus carriers, monkeys infected with the virus. From person to person and from animals, the virus is transmitted by the bites of mosquitoes of the genus Aedes (A. aegipti and A. albopictus), which are also carriers of dengue, yellow fever, and chikungunya. The mosquito poses the greatest epidemic danger A. aegipti, which is common in tropical and subtropical regions but does not survive over low temperatures. A. albopictus is also capable of transmitting the virus, but can hibernate and survive in cooler regions. Mosquitoes are infected with the virus from infected people and animals. The possibility of adaptation of the virus to the body of mosquitoes of other species is not excluded.

For female mosquitoes A. aegipti and A. albopictus intermittent feeding is characteristic, as a result of which they bite several people per feeding cycle. 3 days after the completion of the feeding cycle, the female mosquito lays eggs, which can last up to a year in the absence of water. In the aquatic environment, the eggs turn into larvae, and then into sexually mature individuals. Very little water is needed for the development cycle. Mosquitoes of the above-described species can fly a distance of no more than 400 m, but are often unintentionally brought in by people, for example, in car trunks, with things, plants, over long distances. If able to survive and reproduce in the new temperature climate, mosquitoes can spread the virus in regions where they have been introduced.

The main transmission mechanism of the pathogen is transmissible. At the moment, cases of infection through sexual contact and blood transfusion are described. Also, according to Brazilian scientists, the virus penetrates the hematoplacental barrier, causing intrauterine infection of the fetus, followed by the development of severe congenital pathology.

The natural reservoir of the virus is still unknown.

The pathogenesis of the disease this moment also little studied. Recent studies have shown that the virus primarily infects dermal fibroblasts, epidermal keratinocytes, immature dendritic cells at the site of introduction, then reaches the lymph nodes with subsequent hematogenous spread. The phosphatidylserine receptor AXL, located on the surface of immune skin cells, is responsible for the adhesion and penetration of the virus into target cells. In these cells, affected nuclei were found at the site of the alleged introduction of the virus. An increase in viral replication causes the production of type I interferon and autophagosomes in cells. The high sensitivity of the virus to type I and type II interferons has been proven. During the course of the disease, there is a persistent increase in the activity of T cells (mainly Th1, Th2, Th9 and Th17), which is expressed in an increase in the level of the corresponding cytokines with a clear increase towards the period of convalescence.

The manifestation of the disease, according to the World Health Organization, occurs in 1 out of 5 cases of infection, which is also typical for other flavivirus infections.

The incubation period of the disease is unknown. According to some sources, it is from 2 to 7 days, according to others it can last up to two months (in connection with which the United States introduced a ban on donation for two months for all those who returned from endemic areas).

The clinical picture of the disease is diverse, similar to that of dengue fever and chikungunya. The duration of the disease is from 2 to 7 days. More often the disease begins with the onset of fever, although in some cases it can occur against the background of normothermia. Headache, pain in muscles and joints, conjunctivitis are characteristic. Usually on the 2-3rd day of illness on the skin of the trunk, neck, upper and lower extremities(sometimes including the palms and feet) a maculopapular rash appears (Fig. 3). The development of conjunctivitis is often noted. In rare cases, the disease may be accompanied by dizziness, vomiting, diarrhea, and abdominal pain. In general, the disease proceeds benignly and, unlike Dengue fever, the development hemorrhagic syndrome not noted. Cases of manifestation of the disease with isolated conjunctivitis are known. There is evidence that infection is of particular danger to pregnant women in the first trimester of pregnancy, due to the penetration of the virus through the hematoplacental barrier with subsequent development intrauterine infection leading to a serious pathology of fetal development (microcephaly). In 2015, a case of infection of a pregnant woman at the end of the first trimester of pregnancy was described. At the time of the transfer of the disease, accompanied by fever and rash, the woman lived in Brazil. Fetal microcephaly was detected by ultrasound at the 29th week of pregnancy. After an emergency artificial delivery of the patient, a fetal autopsy was performed, which confirmed the presence of microcephaly with components of hydrocephalus, agyria and the presence of foci of multifocal inflammation, petrificates. The Zika virus was detected in the fetal brain by polymerase chain reaction (PCR) and electron microscopy. There is evidence of a connection between Zika fever and the development of Guillain-Barré syndrome, as well as various autoimmune reactions.



There is currently no evidence that Zika virus in recovered women poses a risk of infection of the fetus in future pregnancies. The Zika virus usually remains in the blood of an infected person for about a week.

In view of light flow diseases specific treatment not required. It is recommended to comply with bed rest, the use of any available non-steroidal anti-inflammatory drugs. Recommended for detoxification plentiful drink. If symptoms worsen, seek medical attention. Special attention should be given to pregnant patients.

Due to clinical similarity with other tropical fevers, clinical diagnosis is not very informative.

For laboratory diagnosis of Zika, the method of choice is PCR and isolation of the virus from blood samples. Serological diagnosis not very informative due to cross-reactions with other flaviviruses such as dengue fever virus, West Nile virus and yellow fever virus.

Disease prevention and control is to reduce the number of mosquitoes by converting and/or destroying their breeding grounds, reducing the likelihood of their contact with the population through the use of repellents, mosquito nets on doors and windows, mosquito nets for sleeping. It should be remembered that for breeding mosquitoes of the genus Aedes very little water is required, so agricultural water tanks (buckets, barrels, plant pots, etc.) must be emptied. Public health work with the population also plays an important role. Particular care should be taken when traveling to areas endemic for the disease: use personal protective equipment (repellents, closed clothing), and avoid places where mosquitoes spread.

In the United States, people who have returned from Zika endemic areas are warned against sexual contact: abstain altogether if there is a pregnant partner and be careful in all other cases.

The World Health Organization is helping countries control Zika virus disease in the following ways:

• prioritize research on Zika virus disease by convening experts and partners;
• strengthen surveillance for Zika virus and potential complications;
• enhance the capacity to communicate proliferation risk to assist countries in meeting their obligations under the International Health Regulations;
• provide specialized training in clinical management, diagnosis and vector control, including through a number of World Health Organization collaborating centres;
• to strengthen the capacity of laboratories to detect the virus;
• support health authorities in implementing a vector control strategy focused on reducing mosquito populations Aedes such as providing larvicides to treat stagnant water in places that cannot be treated otherwise, ie by washing, emptying, covering;
• prepare recommendations for clinical care and follow-up of people virus-infected Zika, in collaboration with experts and other health organizations.

According to the Federal Service for Supervision of Consumer Rights Protection and Human Welfare in the Russian Federation dated February 15, 2016, the first imported case of Zika fever was registered.

The patient is in a boxed department of the infectious diseases hospital in a satisfactory condition. Tested contact family members tested negative for Zika virus.

Before the development of the disease, the patient returned from tourist trip to the Dominican Republic. A few days after the return, a deterioration in health, the appearance of fever, and a rash were recorded.

The patient was immediately admitted to the hospital with a recommendation for examination for hemorrhagic fevers. According to the results of a laboratory study by a domestic test system, RNA of the Zika virus was detected in the biological fluids of the diseased woman.

On board the flight on which the patient arrived, a complex of anti-epidemic measures was taken, there is no danger for those who arrived on this flight.

Since the beginning of 2016, Rospotrebnadzor has begun weekly monitoring of people arriving from countries that are unfavorable for transmissible fevers. As of February 15, 2016, more than 50,000 people were screened for signs of infectious diseases at airports and sea checkpoints receiving flights from South and Central America and the Caribbean, Brazil, Southeast Asia and Oceania and Africa.

Rospotrebnadzor also reports that climatic conditions The Russian Federation is not at risk of spreading Zika. Attention is also drawn to the planning of holidays in the countries of the tropical and subtropical regions: it is preferable to choose countries that are prosperous in epidemiological terms.

If one or more symptoms of the disease appear (fever, rash, conjunctivitis, muscle and joint pain, chills, general weakness) within 2-3 weeks after returning from countries endemic for the Zika virus, you should immediately consult a doctor.

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Yu. Ya. Vengerov, doctor of medical sciences, professor
O. V. Parfenova 1

GBOU VPO MGMSU them. A. I. Evdokimova Ministry of Health of the Russian Federation, Moscow




Countries in the North American region Countries in the South American region Countries in the Asia-Pacific region Area of ​​distribution of Zika Fever Area of ​​distribution of Zika Fever data Cases have been reported in 40 countries.





Countries not affected by Zika virus Brazil lab-confirmed cases, 70,611– suspected DV cases Dominican Republic Ecuador El Salvador Fiji French Guiana 88 lab-confirmed cases, 1,430– suspected DV cases Guatemala – 109 lab-confirmed cases, 278 suspected DV Jamaica Maldives Marshall Islands Martinique Mexico - 65 laboratory confirmed cases Nicaragua - 47 laboratory confirmed cases Panama - 42 laboratory confirmed cases Paraguay Puerto Rico - 30 laboratory confirmed cases Thailand Venezuela Total number more than 120 thousand people have been affected, including 1983 with a laboratory-confirmed diagnosis.





REGISTRATION OF A CASE OF ZIKA FEVER IMPORTATION TO THE TERRITORY OF THE RUSSIAN FEDERATION The first case of Zika fever importation has been registered in the Russian Federation. The patient was on vacation in the Dominican Republic. Upon arrival in Moscow, there were no clinical manifestations of the disease; a few days after the return, a deterioration in health, fever, and a rash were recorded. According to the results of a laboratory study of domestic test system Zika virus was detected in the patient's body fluids. Upon arrival, the entire range of necessary anti-epidemic measures was carried out on the aircraft that the sick woman arrived from the Dominican Republic, and there is no threat to the health of passengers.


























CLINICAL PICTURE - minor headaches; - general malaise; - itchy macular or papular rash on the skin (the rash first appears on the face and then spreads throughout the body); - fever; - pain in muscles and joints with possible swelling of small joints; - hyperemia and inflammation of the conjunctiva (conjunctivitis); - pain in the area of ​​the orbits of the eyes; - intolerance to bright light.




















In Brazil, 1248 cases of intrauterine fetal injury were reported in 2015. In early 2016, 7 countries reported an increase in cases of microcephaly and Guillain-Barré syndrome. It is necessary to use barrier methods of contraception during the entire period of stay in endemic countries and within 28 days after return.