The term yellow fever in medicine refers to a viral infection that is accompanied by damage to various organs and tissues. The carrier of the pathogen is a mosquito, which lives only in some countries. The course of the disease often becomes severe and is accompanied by hemorrhagic syndrome. There is no specific treatment against the infection, but a vaccine has been invented that promotes the production of antibodies and the development of stable but temporary immunity.

Causes

The fever vector is a virus whose genetic material is contained in RNA. It is stable in the external environment and tolerates cold exposure well, but dies at temperatures above 700C or under the influence of ultraviolet irradiation and disinfectants.

The source of infection is animals (marsupials, monkeys, rodents) and people. Fever is transmitted transmissibly (that is, through the bite of mosquitoes that breed near residential buildings). After biting a host, the insects become infectious within a few days. The exact timing depends on both weather and temperature conditions.

It is extremely rare that infection occurs through contact. This is possible when the blood of a sick animal gets on an open wound surface, for example, when processing carcasses.

Yellow fever is prone to epidemics. To do this, it is enough to meet only three conditions:

• presence of virus carriers;
• presence of vectors;
• favorable weather conditions (spread is not possible at temperatures below 18 °C).

There are a number of dangerous countries in which you can become infected. The occurrence of epidemics in other regions is unlikely.

When the disease is yellow fever, the pathogen enters the human bloodstream from the digestive tract of an insect. Then it actively multiplies and accumulates in the lymphatic system. Then it penetrates the general bloodstream and spreads through the vessels, causing their inflammation. The spleen, kidneys, liver, bone marrow, central nervous system and heart are also affected.

Africa is where yellow fever is common

Symptoms

When infected with yellow fever, symptoms begin to appear after a week. In the clinical course of the disease, four phases can be distinguished, which successively replace each other:

• hyperemia;
• short-term improvement;
• venous stasis;
• recovery.

The hyperemia phase is characterized by a sudden significant increase in body temperature. At the same time, intoxication symptoms of yellow fever appear:

• nausea;
• muscle weakness;
• joint pain;
• headache;
• disorders of higher nervous activity (impaired consciousness, delusions and hallucinations).

The patient's appearance also changes. The face and neck become somewhat swollen, there is redness of the skin and minor hemorrhages in the sclera, oral mucosa, and conjunctiva. In some cases, patients begin to experience photophobia and experience increased lacrimation.

The main symptoms are yellowing of the skin, as well as a significant increase in temperature, which is how the disease got its name.

Systemic manifestations include:

• change in rhythm (tachycardia turning into bradycardia);
• decreased blood pressure;
• small volume of daily urine;
• enlarged spleen and liver;
• discoloration of the sclera and skin in a yellowish color.

The first phase lasts about four days, after which there is a short period of improvement. It can last from 2-5 to 24-35 hours. At the same time, there is an objective improvement in well-being against the background of a decrease in temperature. In some cases, immediately after this period the patient recovers, but in severe cases of yellow fever, a short remission is followed by a phase of venous stagnation.

Yellow eyes (progressive jaundice)

In yellow fever, the next phase includes the following symptoms:

• pale skin;
• cyanosis of the lips, as well as peripheral parts of the extremities;
• progressive jaundice;
• pinpoint hemorrhages and purpura;
• significant hepatosplenomegaly.

The patient's condition is much worse than during the hyperemic phase. In connection with hemorrhagic syndrome the following are associated:

• bleeding from the nose, gums;
• gastrointestinal bleeding, manifested by melena and vomiting of coffee grounds;
• hemorrhages in internal organs.

During this period, urine often stops being produced altogether, which increases the intoxication of the body. If the course is favorable, a period of recovery follows, but not all patients with yellow fever manage to survive the phase of venous stagnation. In most cases, after recovery, a stable immune defense is formed.

Diagnostics

Diagnosis of the disease is based on analysis of the epidemic situation and assessment of the clinical picture. A number of instrumental techniques are also used:

• a blood test that can detect a decrease in the level of white blood cells, platelets and neutrophils. Further, there is an increase in the concentration of cellular elements and accumulation of metabolic products (urea, creatinine), as well as an increase in the level of liver enzymes and bilirubin;
• urine analysis may contain protein, red blood cells, columnar epithelium;
• using a serological test, the presence of specific antibodies can be detected;
• The yellow fever virus can be identified in the blood using the PCR technique. Due to the danger of an epidemic, biological material should only be handled in a specialized laboratory.

Treatment

Treatment for yellow fever should be started as soon as possible. To do this, the patient should be placed in a separate box in an infectious diseases hospital.

There is currently no specific therapy aimed at eliminating the virus, so only symptomatic treatment is carried out to alleviate the patient’s condition.

Typically, the following classes of medications are prescribed to treat yellow fever:

• anti-inflammatory steroidal or non-steroidal drugs;
• hemostatic (hemostatic) agents;
• antiallergic drugs;
• detoxification solutions (glucose, salts, dextrans);
• diuretics.

In case of severe renal failure, plasmapheresis is performed. If there is blood loss or a serious bleeding disorder, blood products, including plasma and platelets, are used. In case of secondary bacterial infection, antibacterial agents are prescribed.

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There are diseases that are incurable. Of course, the world would be a better place without them, but reality sometimes turns out to be very, very cruel. In this case, we are not talking about some kind of congenital defects, but about diseases that a person can catch accidentally. So to speak, by chance. Sometimes it happens that one moment decides the outcome of your entire life, because an acquired infection can ruin everything at once, cross out your fate and deprive you of the possibility of a normal existence.

What is yellow fever

This is a very insidious and incurable disease. It is also known as West Nile fever. Most common in South America and Africa. In approximately sixty percent of all cases, yellow fever is fatal. It is usually transmitted by mosquitoes and mosquitoes.

What are its signs and why is it so dangerous?

There are two types of it:

Jungle Fever;

City fever.

Jungle fever mostly affects young people who work in the jungle in logging. Epidemic outbreaks are not at all typical for it. In addition to mosquitoes and mosquitoes, it can be carried by various wild animals. Urban fever is characterized by epidemics, since in this case the person himself can act. It spreads very quickly and claims many lives.

Yellow fever has an incubation period that can last for four or even six days. here are the following:

A sharp increase in body temperature;

A person who suffers from yellow fever must be hospitalized and quarantined. He is given antiviral and symptomatic drugs, as well as many vitamins. In fact, there is no cure for yellow fever, and during the entire treatment, doctors do not fight the infection itself, but only its symptoms (liver failure, etc.). Doctors constantly have to treat one thing or another. Yellow fever cannot be completely cured, and the body suffers greatly from it. Those who were nevertheless able to overcome all the main symptoms may develop such unpleasant consequences as gangrene, pneumonia, sepsis, and many others. These consequences can appear immediately or after several years.

Yellow fever: vaccination

The best means of prevention in this case is vaccination. Thanks to it, the body gets the opportunity to develop a certain immunity, with which yellow fever will not be scary for it, in just one week. The vaccine is actually very effective and allows you to protect yourself for about six to seven years.

The content of the article

Yellow fever(synonyms for the disease: amaryllosis, amarylline typhus) is an especially dangerous acute infectious natural focal infectious disease, which is caused by the same arbovirus, transmitted by mosquitoes, characterized by a sudden onset, two-phase course, hemorrhagic syndrome, damage to the liver, circulatory organs, kidneys and other organs. Refers to quarantine infections and is subject to registration with WHO.

Historical data of yellow fever

The first epidemics of yellow fever (Spanish amarillo - yellow) with high mortality were known in Central America and West Africa in 1647-1648 pp. N. R. Carter. The disease was repeatedly introduced into countries in Europe and North America. In 1881, the Cuban doctor K. Finlay suggested the viral nature of the disease and its transmission by mosquitoes. In 1901, viral etiology was proven by a special commission in Cuba, which was headed by the American military doctor W. Reed. In the 20th century. yellow fever is recorded mainly in the tropical zones of Africa and South America.

Etiology of yellow fever

The causative agent of yellow fever, Flavivirus febricis, belongs to the genus Flavivirus, family Togaviridae. The virion is 40-50 nm in size and contains single-stranded RNA.
It is reproduced in different cell cultures; chicken embryos, monkeys, pigs, guinea pigs, and cats are sensitive to it. The pathogen is sensitive to ether, detergents, and formaldehyde. At a temperature of 56 ° C loses activity within 10 min.3n

Epidemiology of yellow fever

There are two epidemiological types of yellow fever cells - endemic, or natural (jungle), and epidemic, or anthropourgical (urban).
The reservoir of infection in natural (jungle) foci of the disease are monkeys, possibly rodents, marsupials, hedgehogs and other animals, and the carriers are mosquitoes from the genera Aedes in Africa and Haemagogus in America. The penetration of the yellow fever virus into cities can lead to the formation of an epidemic (anthroponotic) type of yellow fever cells. The reservoir of infection in these foci is a sick person, and the carrier is Aedes aegypti mosquitoes. Mosquitoes are capable of infecting humans 6-12 days after ingesting infected blood. The endemic (jungle) form of yellow fever is characterized by sporadic illness, less often - group outbreaks, epidemic (urban) - epidemic outbreaks.
Immunity after an illness is stable and lifelong. The distribution area of ​​the disease covers areas between 40°S. w. and 42 ° N. w. Registered in the countries of South and Central America and Africa - Bolivia, Brazil, Colombia, Peru, Angola, Mali, Nigeria, Togo, etc.

Pathogenesis and pathomorphology of yellow fever

After the virus enters the body and reproduces it for 3-6 days, viremia develops in the cells of the mononuclear phagocyte system, causing dissemination of the pathogen to the liver, kidneys, spleen, bone marrow and other organs. They experience inflammatory-degenerative and necrotic processes. Vascular damage leads to the development of severe hemorrhagic syndrome with hemorrhages of various locations. Perivascular infiltrates and hemorrhages appear in the brain.

Yellow fever clinic

The incubation period lasts 3-6 days.
There are four periods, or phases, of the disease:
1) initial (hyperemia)
2) short-term remission,
3) venous stasis,
4) recovery.
Initial period (hyperemia phase) lasts 3-4 days. The onset of the disease is acute, body temperature with chills rises to 39-41 ° C. Intense headache, muscle and lower back pain, nausea, and repeated vomiting appear. Characterized by a gradual change in the color of the vomit over the course of the disease from yellow (the color of bile) to black, like soot (Vidal's sign). A typical appearance of the patient, which is called the amaryl mask: the face is puffy, purplish-red, the eyes are shiny, the sclera and conjunctiva are hyperemic, photophobia, lacrimation, plump, scarlet lips. The skin of the neck and upper chest becomes red. From the first days of the illness, a peculiar odor is felt from the patients’ mouth, reminiscent of the smell of a butcher shop (Ferrari sign). The liver is enlarged and painful. Delirium and psychomotor agitation are often observed. The pulse is rapid at first, then turns into relative bradycardia, blood pressure is reduced. At the end of the hyperemia phase, slight icterus of the sclera and skin, hyperbilirubinemia, and increased activity of serum aminotransferases appear. A petechial rash may appear on the skin. Blood tests reveal leukopenia with thrombocytopenia.
After 3-5 days, the period of hyperemia is replaced by period of short-term remission, which lasts from several hours to one day. Body temperature decreases, general condition improves, pain decreases, and vomiting stops. This period can transition into a period of recovery, but more often a period of venous metastases develops. The period of venous metastases. The patient's condition quickly deteriorates, body temperature rises again, jaundice increases significantly, and severe hemorrhagic syndrome develops. An increase in body temperature is often combined with a decrease in pulse rate (Faget's sign), which is 50-40 per minute. Puffiness and hyperemia of the face disappear, the skin of the face and the whole body is pale with a significant cyanotic tint (venous stagnation). Against the background of jaundice, a hemorrhagic rash appears on the skin and mucous membranes in the form of petechiae and ecchymoses. Bloody vomiting, melena, hematuria, and uterine bleeding appear. Kidney failure develops (oligoanuria, hyperazotemia), infectious-toxic shock. Death occurs on the 6-9th day of illness from kidney failure and toxic encephalitis, less often from liver failure, myocarditis. From the blood side, during this period, leukopenia (rarely leukocytosis) is detected with a shift in the leukocyte formula to the left, and thrombocytopenia increases. In the urine there is protein, red blood cells, casts.
Recovery period (reconvalescence) begins on the 9-10th day of illness. Body temperature decreases, clinical and laboratory parameters gradually normalize, undergo reverse development, and all pathological changes disappear.
A mild course of the disease with short-term (1-3 days) fever without jaundice and hemorrhagic syndrome is also observed. Diagnosis in such cases is significantly difficult and is based “on laboratory data and taking into account the epidemiological situation.

Complications of yellow fever

Possible bleeding, pneumonia, myocarditis, mumps, encephalitis, gangrene of the limbs, cheeks (noma), uremia.
The prognosis is always serious. Depending on the nature of the epidemic, the mortality rate ranges from 1 to 30% or more.

Diagnosis of yellow fever

The main symptoms of the clinical diagnosis of yellow fever are the acute onset of the disease, its two-wave course, fever, amaryl mask symptom, Ferrari, Vidal, Fage signs, a combination of jaundice with hemorrhagic syndrome, manifestations of kidney failure. The epidemiological history is also taken into account - stay in an area endemic for this disease.
Specific diagnostics is based on the isolation of the virus from the blood in the first 3-4 days of illness (in the hyperemia phase). Serological studies in the dynamics of the disease (paired sera method) using RGNGA, RSK, HP1F, RN allow retrospective confirmation of the diagnosis, since specific antibodies appear only after the 2nd week of the disease.

Differential diagnosis of yellow fever

Yellow fever should be differentiated from viral hepatitis, leptospirosis, tropical malaria, and other hemorrhagic fevers.

Treatment of yellow fever

Treatment involves the complex use of detoxification and anti-shock drugs, large doses of glycocorticosteroids, blood transfusions and blood-containing solutions. At the onset of the disease, it is advisable to administer interferon (reaferon) parenterally. Homeostasis is corrected. If kidney and liver failure develops, hemodialysis is indicated.

Prevention of yellow fever

Patients are subject to hospitalization in hospitals that are protected from mosquitoes. In endemic areas, measures are taken for individual and collective protection from mosquito attacks, as well as for their destruction. Specific prevention in foci of infection is carried out with the live Teiler vaccine from attenuated strains 17-D, and less often with the Dakar vaccine. 0.5 ml of the vaccine is administered subcutaneously in a dilution of 1:10. Antibodies appear 7-10 days after vaccination. Immunity lasts for 6 years. Vaccinated persons are issued certificates that are valid from the 1st day after vaccination. Unvaccinated persons arriving from areas where yellow fever has been reported are subject to quarantine for 9 days (monkeys and other animals for 7 days).

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Yellow fever

What is Yellow Fever -

Yellow fever(yellow fever, fievre jaune, fiebre amarilla, vomito negro, febris flava) is an acute obligate-transmissible disease with natural focality from the group of viral hemorrhagic fevers. Refers to particularly dangerous infections. Characterized by a severe course with high fever, liver and kidney damage, jaundice, and bleeding from the gastrointestinal tract. The clinical picture of yellow fever was first described during an outbreak in America in 1648. In the 17th-19th centuries, numerous epidemics were recorded in Africa and South America, and outbreaks of the disease in southern Europe. The vector-borne route of transmission of infection through Aedes aegypti mosquitoes was established by K. Finlay (1881), its viral etiology was established by W. Reed and D. Carroll (1901). The natural focality of the disease, the role of monkeys in the circulation of the pathogen in the foci was established by the studies of Stokes (1928) and Soper et al. (1933). In 1936, Lloyd et al. developed an effective vaccine against yellow fever.

What provokes / Causes of Yellow fever:

The causative agent of yellow fever- RNA genomic virus Viscerophilus tropicus of the Flavivirus genus of the Flaviviridae family. The diameter of viral particles is 17-25 nm. It is antigenically related to the Japanese encephalitis and dengue fever viruses. Pathogenic to monkeys, white mice and guinea pigs. Cultivated in developing chick embryos and tissue cultures. It is stored for a long time (more than a year) in a frozen state and when dried, but at 60 ° C it is inactivated within 10 minutes. It quickly dies under the influence of ultraviolet rays, ether, and chlorine-containing drugs in normal concentrations. Low pH values ​​have a detrimental effect on it. Populations at risk of yellow fever The population of 45 endemic countries in Africa and Latin America, totaling more than 900 million people, is at risk. In Africa, an estimated 508 million people living in 32 countries are at risk. The remaining populations at risk live in 13 Latin American countries, with Bolivia, Brazil, Colombia, Peru and Ecuador most at risk. An estimated 200,000 cases of yellow fever occur worldwide each year (30,000 of which are fatal). A small number of imported cases occur in countries free of yellow fever. Although the disease has never been introduced into Asia, the region is at risk because it has the conditions necessary for transmission. Reservoir and sources of infection- various animals (monkeys, marsupials, hedgehogs, possibly rodents, etc.). In the absence of a carrier, a sick person is not dangerous to others. Transmission mechanism- transmission. The carriers are mosquitoes of the genera Haetagogus (on the American continent) and Aedes, especially A. aegypti (in Africa), which have a close connection with human habitation. Vectors breed in decorative ponds, water barrels, and other temporary water reservoirs. They often attack humans. Mosquitoes become infectious within 9-12 days after blood-sucking at ambient temperatures up to 25°C and after 4 days at 37°C. At temperatures below 18 °C, the mosquito loses its ability to transmit the virus. If infected blood comes into contact with damaged skin and mucous membranes, a contact route of infection is possible. Natural receptivity people are high, post-infectious immunity is long-lasting. Main epidemiological features. Yellow fever is classified as a quarantine disease (a particularly dangerous disease) subject to international registration. The highest incidence is recorded in tropical areas, but outbreaks of this disease occur almost everywhere where there are carriers of the virus. The spread of the virus from endemic areas can occur both through sick individuals and through mosquitoes during the transportation of goods. There are two types of foci: natural (jungle) and urban (anthropurgic). The latter more often manifest themselves in the form of epidemics; in this case, the sources of infection are patients during the period of viremia. In recent years, yellow fever has become more of an urban disease and has acquired the features of anthroponosis (transmission occurs through the chain “human - mosquito - human”). If there are conditions for the spread of the pathogen (virus carriers, a large number of carriers and susceptible individuals), yellow fever can become epidemic.

Pathogenesis (what happens?) during Yellow Fever:

Reproduction of the virus that enters the body through a mosquito bite occurs in regional lymph nodes during the incubation period. During the first few days of illness, the virus disseminates through the bloodstream throughout the body, causing damage to the vascular apparatus of the liver, kidneys, spleen, bone marrow, myocardium, brain and other organs. They develop pronounced dystrophic, necrobiotic, hemorrhagic and inflammatory changes. Characterized by multiple hemorrhages in the gastrointestinal tract, pleura and lungs, as well as perivascular infiltrates in the brain.

Symptoms of Yellow Fever:

There are three variants of yellow fever in humans. These are jungle fever (rural type), city fever and an intermediate type. Rural option(yellow jungle fever). In tropical forests (selva), yellow fever occurs in monkeys infected by the bites of “wild” mosquitoes. Infected monkeys can spread the infection by passing it on to healthy mosquitoes. Infected "wild" mosquitoes bite and transmit the virus to people in the forest. This chain leads to isolated cases of infection, mainly in young people working in logging, without leading to epidemics or large outbreaks. The infection can also spread between infected people. Intermediate option infection occurs in humid or semi-humid African savannas and is the dominant form of infection on the continent. There are limited-scale epidemics that differ from the urban variant of the infection. “Semi-domestic” mosquitoes infect both animals and people. During such epidemics, several villages can be affected simultaneously, but the mortality rate with this variant of yellow fever is lower than with urban ones. Urban option infections are accompanied by large-scale epidemics, which are caused by the influx of migrants into urbanized regions with high population densities. "Domestic mosquitoes" (species Aedes aegypti) transmit the virus from person to person; monkeys are not involved in the epidemic chain of transmission of the disease. Incubation period lasts about a week, occasionally up to 10 days. In typical cases, the disease goes through several successive stages. Hyperemia phase. The acute onset of the disease is manifested by a rapid increase in body temperature above 38 °C with chills, headache, myalgia, pain in the back muscles, nausea and vomiting, agitation and delirium. In the dynamics of this phase of the disease, these symptoms persist and intensify. When examining patients, hyperemia and puffiness of the face, neck, shoulder girdle, bright hyperemia of the vessels of the sclera and conjunctiva, photophobia, and lacrimation are noted. Hyperemia of the tongue and oral mucosa is very characteristic. Severe tachycardia persists in severe cases of the disease or is quickly replaced by bradycardia, and initial arterial hypertension is replaced by hypotension. The size of the liver and, less commonly, the spleen increase slightly. Oliguria, albuminuria, and leukopenia occur. Cyanosis, petechiae appear, and symptoms of bleeding develop. At the end of the phase, icterus of the sclera may be noted. The duration of the hyperemia phase is 3-4 days. Short-term remission. Lasts from several hours to 1-2 days. At this time, the body temperature usually decreases (down to normal values), the well-being and condition of the patients improve somewhat. In some cases, with mild and abortive forms, recovery gradually occurs in the future. However, more often, after a short-term remission, high fever occurs again, which can last up to 8-10 days, counting from the onset of the disease. In severe cases, remission is replaced by a period of venous stasis. During this period, there is no viremia, but fever persists, pallor and cyanosis of the skin, icteric staining of the sclera, conjunctiva and soft palate are noted. The patient's condition worsens, cyanosis, as well as jaundice, progress rapidly. Widespread petechiae, purpura, and ecchymosis occur. Hepatolienal syndrome is pronounced. Characterized by vomiting blood, melena, bleeding gums, and organ bleeding. Oliguria or anuria and azotemia develop. Infectious-toxic shock and encephalitis are possible. Infectious-toxic shock, renal and liver failure lead to the death of patients on the 7-9th day of illness. Complications infections can be pneumonia, myocarditis, gangrene of soft tissues or extremities, sepsis as a result of the layering of a secondary bacterial infection. In cases of recovery, a long period of convalescence develops. Post-infectious immunity is lifelong.

Diagnosis of Yellow Fever:

In Ukraine, yellow fever can only occur in the form of imported cases. In clinical differential diagnosis, attention is paid to the sequential change of the main two phases in the development of the disease - hyperemia and venous stasis - with a possible short period of remission between them. Laboratory data The initial stage of the disease is characterized by leukopenia with a sharp shift to the left, neutropenia, thrombocytopenia, at its height - leukocytosis, progressive thrombocytopenia, increased hematocrit, blood nitrogen and potassium. The amount of protein in the urine increases, red blood cells and casts appear. Hyperbilirubinemia and high activity of aminotransferases (mainly AST) are noted. In specialized laboratories, it is possible to isolate the virus from the blood in the initial period, using biological diagnostic methods (infection of newborn mice). Antibodies to the virus are determined using RNGA, RSK, RNIF, indirect hemagglutination inhibition reaction, ELISA.

Treatment of Yellow Fever:

Treatment of yellow fever is carried out according to the same principles as hemorrhagic fever with renal syndrome, in the conditions of infectious diseases departments for working with especially dangerous infections. Causal therapy has not been developed. Convalescent blood plasma, used in the first days of illness, gives a weak therapeutic effect. Forecast: the mortality rate of the disease ranges from 5%-10% to 15-20%, and during epidemic outbreaks - up to 50-60%.

Prevention of Yellow Fever:

Preventive actions are aimed at preventing the introduction of the pathogen from abroad and are based on compliance with the International Health Regulations and the Rules for the sanitary protection of the territory. They destroy mosquitoes and their breeding sites, protect premises from them and use personal protective equipment. Specific tests are carried out at foci of infection immunoprophylaxis with live attenuated vaccine. It is administered subcutaneously to persons of all ages in a volume of 0.5 ml. Immunity develops within one week in 95% of vaccinated people. Immunity develops after 7-10 days and lasts for at least 10 years. Vaccination of children and adults is carried out before leaving for endemic areas (South Africa), where the disease in new arrivals is very severe and has a high mortality rate. Immunization against yellow fever is recommended:- persons traveling on business or tourism (even for a short time), or living in a region where the disease is endemic, - unvaccinated persons traveling from an endemic to a non-endemic region. In accordance with the established rules, a stamp of vaccination against yellow fever must be affixed to the International Certificate, as well as signed and approved by an accredited yellow fever vaccination center. - This vaccination certificate is valid for 10 years, starting from the 10th day after the date of vaccination. - persons at risk of infection due to their professional duties, HIV-infected persons in the asymptomatic stage. In accordance with established rules, a mark on vaccination against yellow fever must be affixed to the International Certificate, as well as signed and approved by an accredited yellow fever vaccination center. This vaccination certificate is valid for 10 years, starting on the 10th day after the date of vaccination. Contraindications to vaccination against yellow fever: General contraindications for yellow fever vaccination are similar to those for any vaccination: - infectious diseases in the active stage, - progressive malignant diseases, - current immunosuppressive therapy. Specific contraindications: - documented allergy to egg whites, - acquired or congenital immunodeficiency. Pregnant women and children under 6 months of age are not recommended to be vaccinated. However, in the event of an epidemic, pregnant women and infants from 4 months of age can be vaccinated. In difficult cases, you should consult a doctor. Precautions for yellow fever vaccination- In persons with allergic diseases, a test is indicated to assess sensitivity to the drug by intradermal administration of 0.1 ml of the vaccine. If there are no reactions within 10 - 15 minutes, the remaining 0.4 ml of vaccine should be administered subcutaneously. - In special cases, a decision may be made to vaccinate patients receiving immunosuppressive therapy. It is best not to vaccinate until 1 month after the end of such therapy and, in any case, you should make sure that the biological indicators are within normal limits. - In difficult cases, you should consult a doctor. Adverse reactions Sometimes, 4-7 days after vaccination, general reactions may occur - headache, malaise, slight increase in body temperature. Activities in the epidemic outbreak Patients are hospitalized in the infectious diseases department. If a sick person is detected on a ship during a voyage, he is isolated in a separate cabin. Disinfection is not carried out in the outbreak. Any vehicle arriving from countries affected by yellow fever must have information about the disinfestation carried out. Unvaccinated persons arriving from endemic areas are subject to isolation with medical supervision for 9 days. If an outbreak of yellow fever occurs, mass immunization of the population begins immediately. List of countries requiring an international certificate of vaccination against yellow fever. 1. Benin 2. Burkina Faso 3. Gabon 4. Ghana 5. Democratic Republic of the Congo 6. Cameroon 7. Congo 8. Ivory Coast 9. Liberia 10. Mauritania 11. Mali 12. Niger 13. Peru (only when visiting jungle areas) 14. Rwanda 15. Sao Tome and Principe 16. Togo 17. French Guiana 18. Central African Republic 19. Bolivia List of countries with zones endemic for this infection, upon entry to which it is recommended to have an international certificate of vaccination against yellow fever : South American countries 1. Venezuela 2. Bolivia 3. Brazil 4. Guyana 5. Colombia 6. Panama 7. Suriname 8. Ecuador African countries 1. Angola 2. Burundi 3. Gambia 4. Guinea 5. Guinea-Bissau 6. Zambia 7. Kenya 8. Nigeria 9. Senegal 10. Somalia 11. Sudan 12. Sierra Leone 13. Tanzania 14. Uganda 15. Chad 16. Equatorial Guinea 17. Ethiopia

Which doctors should you contact if you have Yellow fever:

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You? It is necessary to take a very careful approach to your overall health. People don't pay enough attention symptoms of diseases and do not realize that these diseases can be life-threatening. There are many diseases that at first do not manifest themselves in our body, but in the end it turns out that, unfortunately, it is too late to treat them. Each disease has its own specific signs, characteristic external manifestations - the so-called symptoms of the disease. Identifying symptoms is the first step in diagnosing diseases in general. To do this, you just need to do it several times a year. be examined by a doctor, in order not only to prevent a terrible disease, but also to maintain a healthy spirit in the body and the organism as a whole.

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The icteric color of the skin of the face and the entire body is a distinctive sign not only of viral hepatitis, it is one of the typical symptoms of another viral disease - yellow fever. Those who are planning to visit Africa or South America are in for an unpleasant surprise - another injection against a dangerous infection. But it is better to get vaccinated immediately before the expected meeting with the pathogen than to be among those who are forced to deal with its consequences for life.

What kind of disease is yellow fever and why is this disease dangerous? How is the infection transmitted and what pathogen causes it? What are the symptoms at different stages of the disease and how to cope with it? What will help in the fight against yellow fever and what preventive measures are there?

What kind of disease is yellow fever?

What is yellow hemorrhagic fever? This is an acute viral disease with a natural source of infection, the carrier of which is mosquitoes. What else is yellow fever known for? Besides the “screaming” name, it’s worth knowing a little more about the disease.

1. In the middle of the 17th century, scientists discovered foci of the disease in Africa and America. These are the countries that are at risk for morbidity. Africa occupies the leading position, where about 90% of disease cases are registered annually.
2. Before the creation of a vaccine, yellow fever was often epidemic in nature.
3. There are two main types of the disease - the jungle or wild variant, and the urban one. In the second case, uncontrolled epidemics of yellow fever often develop, which quickly spread among people.
4. The infection is transmitted by mosquitoes. The extermination of pockets of insects at one time helped to avoid the spread of the disease.
5. Female mosquitoes can infect a person even a week after the bite, but not within the first 4 days from the moment of infection.
6. And although in our time the number of deaths after suffering a severe infection does not exceed 5%, during massive outbreaks of yellow fever it significantly exceeds this figure. In some cases, mortality reached 50%.

Is the disease dangerous these days, when the source of infection is known and there are all ways to combat it? Undoubtedly, yellow fever, even now, is one of the serious diseases and each case of the disease must be reported to the state sanitary and epidemiological supervision. In Africa, Central and South America, vaccination against yellow fever is vital; during the development of the infection, it is even given to pregnant women.

The causative agent of yellow fever

The yellow fever virus is a flavivirus, but this disease is caused by an arbovirus. Pathogens belonging to this genus are responsible for the occurrence of Dengue fever, tick-borne and Japanese encephalitis. Any of these infections is characterized by a special course and damage to vital organs.

What are the features of this virus?

1. It affects the liver, kidneys and heart.
2. At low temperatures, the virus persists for years in a frozen state, as well as if it is dried.
3. The causative agent of yellow fever affects more than 200 thousand people annually, despite the fact that it is extremely unstable in the external environment and dies under the influence of most disinfectants, ultraviolet radiation and when heated to 60 ° C.
4. After biting a sick person, a female mosquito can infect others for 12 days.

The causative agent of yellow fever is easily inactivated by available inexpensive means. Why do you still need to remember about the disease?

1. In the past, infection was often the cause of mass death.
2. Every person is at risk for this disease when traveling to disadvantaged areas.
3. Outbreaks of yellow fever are recorded in our time every year with varying degrees of intensity.

The difference between a natural infection and an urban one

How does a natural infection differ from a city infection?

Epidemics of yellow fever are recorded when the disease develops in populated areas. But in recent years their number has become less and less common.

There is a list of countries to which anyone will need a yellow fever vaccination to travel. Their list can be easily found in any media. When leaving these regions, a person needs additional examination for the presence of yellow fever virus in the blood, even if he was passing through there on a short business trip. The disease can be transmitted by close people or family members who have visited African and American countries and become infected with yellow fever there.

How does the yellow fever virus behave in the blood?

After a person is bitten by a female mosquito infected with yellow fever, the virus quickly penetrates the blood and rushes to macrophages - protective cells. Once inside, the virus begins to actively multiply. This lasts about four days, but no more than 10, which corresponds to the incubation period of yellow fever.

After an increase in the amount of virus, it goes back into the blood and the phase of active manifestation of the disease begins, when a patient with yellow fever develops all possible symptoms of infection. Damage to the kidneys, liver tissue, heart and brain occurs because the virus is in the blood. Wherever the yellow fever pathogen penetrates through the blood, not only inflammation of tissues occurs, but processes of malnutrition of organs and necrosis or necrosis of some areas occur.

The liver is hit hard, and sometimes irreversible changes develop here. This is why a person develops icteric discoloration of the skin and other familiar symptoms of inflammation of the liver tissue: spider veins, nausea and numerous vomiting that does not bring relief.

After damaging liver cells, the yellow fever virus continues to destroy internal organs and reaches the kidneys, which in most cases ends in acute renal failure.

The presence of the virus in the blood causes damage to many internal organs. The causative agent of yellow fever affects blood vessels, weakens their walls, which contributes to the formation of bruises.

Features of the course of infection

The disease begins suddenly, occurs with acute biphasic fever, affects liver cells, and its typical external sign is yellow discoloration of the skin.

In the development of the disease, there are several periods that follow one after another:

• incubation, lasts from three to ten days;
• then the initial period of yellow fever lasts about four days, characterized by numerous clinical manifestations;
• short-term remission, when a person feels practically healthy for several hours or even a day;
• a period of venous stasis with a sharp deterioration in condition and the appearance of more indicative symptoms;
• recovery with a slow subsidence of all visible and invisible manifestations of the disease.

On average, each period of yellow fever lasts about 9 days. The outcome of the disease depends on the amount of pathogen and the immunity of the infected person. Mild cases are often observed among local residents of areas with frequent outbreaks of the disease.

Symptoms of yellow fever

During the incubation period of yellow fever, the disease does not manifest itself in any way. This is one of the most dangerous periods in terms of epidemics, since it is at this time that the infection is already spread by mosquitoes, and measures to reduce the incidence are not taken due to the absence of symptoms.

During the active manifestation of the disease, the following symptoms of yellow fever may gradually appear.

In the first stages of yellow fever development, symptoms of suppression of the functioning of internal organs appear.

1. The pulse is rapid in the first days, then bradycardia or a slowing of the pulse and a decrease in blood pressure develop due to damage to the kidney tissue.
2. If tachycardia or rapid heartbeat persists, this is an unfavorable prognostic sign for the course of yellow fever.
3. The liver increases in size, its damage is noticeable to the naked eye - the sclera and skin turn yellow, on which small red dots or petechiae are visible.

Then the period of the height of the disease gives way to false prosperity. You can accidentally confuse this period with complete recovery. Almost nothing bothers the patient, and the symptoms disappear for a short time almost without a trace.

Dangerous periods of yellow fever

If a person is lucky, the third stage of the disease may be the last, and the infection actually goes away. But in most cases such a happy outcome is not observed. What worries the person next? After a short rest, the patient's condition deteriorates sharply.

In severe cases of yellow fever, shock develops with its typical manifestations: a rare pulse, a rapid decrease in blood pressure, a small amount of urine up to its complete absence (anuria).

Diagnosis of yellow fever

How to diagnose yellow hemorrhagic fever? Doctors do this, most often in an infectious diseases hospital. During the development of an epidemic, it is much easier to determine an accurate diagnosis. During disease outbreaks, this process is not difficult. A complete history of the development of the disease is collected.

Yellow fever is recognized by the following signs.

1. Residence or temporary stay of a person in places with frequent outbreaks of infection.
2. Typical clinical manifestations of the disease help: biphasic course, liver damage, yellow discoloration of the skin.

A correct diagnosis can only be made after clinical studies. To do this, study the blood of a sick person:

• at the very beginning of the disease, the causative agent of yellow fever is sown;
• in a later period, antibodies in the blood to the virus are determined, for which serological studies of RSK or RPGA are carried out.

The sooner doctors can diagnose yellow fever, the sooner treatment will begin and the greater the chance of a more favorable outcome of the disease.

Treatment

Before treating yellow fever, you need to remember a few important rules.

Otherwise, treatment is carried out according to the general rules of infectious diseases. There is no etiotropic or specific treatment for yellow fever, so doctors most often have to prescribe symptomatic drugs.

1. Detoxification solutions are administered to correct the functioning of the kidneys and liver.
2. Anti-shock measures are being carried out.
3. With repeated vomiting, the loss of fluid and microelements is replenished.
4. In case of renal failure, hemodialysis is performed.

It is important to remember that yellow fever is a quarantine disease. If a person lives in countries with frequent epidemics and has not been vaccinated, then during the growth of the epidemic he is completely isolated for 9 days.

Consequences

Like any other disease, yellow fever can be mild or severe. Although in the case of this disease, a mild course is so rare that it occurs in isolated cases. Then, as already mentioned, in the development of infection, three periods and temporary imaginary well-being are most often observed, after which everything ends with recovery. This is an almost ideal course of yellow fever, when a person’s symptoms are much milder and there are almost no complications. Such “happy” cases occur among residents of countries with frequent epidemics of this disease. However, early diagnosis is difficult, because a person can recover from the infection without yellowing of the skin and other classic symptoms.

But in some cases, the consequences of the disease are much more severe than the infection itself:

• infectious encephalitis or inflammation of the brain may develop;
• pneumonia or pneumonia after yellow fever;
• the most unpleasant thing is death due to damage to the kidneys or liver, with the development of liver or kidney failure.

Those who have contracted the disease do not need to take any additional measures to protect themselves from the mosquito vectors; people develop strong, lifelong immunity to the yellow fever virus.

Prevention of yellow fever

Prevention is divided into two main types: nonspecific and specific. In the first case, a standard set of measures is carried out to eradicate disease vectors (clusters of mosquitoes are destroyed) or to detect a reservoir of infection.

Specific prevention of yellow fever is carried out in medical institutions, often in clinics or hospitals. It consists of administering a live attenuated vaccine to everyone who is at risk for the disease. People visiting dangerous areas are also vaccinated. Correctly administered vaccination provides long-term protection.

Yellow fever is another disease in a long list of dangerous infections that travelers and people who frequently travel abroad need to be aware of. And let the forced need to protect against this disease not frighten such people. This is a prevention not only of yellow fever itself, but also a guarantee that a person will leave the source of infection alive.