Yellow fever - Causes, Symptoms and Treatment .MF .

August 12, 2017 17:52 | Infectious Diseases

Yellow fever - an acute viral disease with natural foci, transmitted by mosquitoes, and characterized by severe intoxication, hemorrhagic manifestations and losing life support organs - liver, kidneys.The name "yellow" is due to the frequent development in patients with symptoms such as jaundice.

Most cases of yellow fever recorded in countries with tropical and subtropical climates.There are two types of yellow fever:
1) endemic (prevalent in rural or jungle),
2) Epidemic (predominantly urban, anthroponotic).

Yellow fever is a particularly dangerous infection (TELO), refers to a quarantine disease, subject of the international registration.Drive to the yellow fever endemic countries require an international certificate of vaccination against this infection.

International Certificate

Natural yellow fever foci are located in tropical areas of South America and Africa.According to the WHO endemic at the moment are 45 countries in Africa and 13 countries in South and Central America, examples

of which are: the Congo, Sudan, Senegal, Bolivia, Peru, Brazil, Mexico, Cameroon, Nigeria, Zambia, Uganda, Somalia and others.

Endemic countries for yellow fever

dangerous development disease outbreaks among the population.For example, in 2012 during an outbreak in Sudan was ill 850 patients, 171 of which were fatal.Outbreaks occur in endemic countries annually.The only preventive measure is vaccination, which due to reduced morbidity.

causative agent of yellow fever

Yellow fever is arbovirus of the family Flaviviridae genus Flavivirus.The virus genome contains RNA.Strains from different places of Africa and America are not genetically uniform.

Yellow fever virus

virus in the environment is stable enough, dies quickly when exposed to heat and normal dez.sredstv.The virus persists long in the frozen state and upon drying.

Yellow fever virus is related to pathogenicity group 1 (all kinds of work with such viruses are carried out in a maximum containment laboratory).The virus can be isolated from the blood of a patient with yellow fever during the first three days of illness by using white mice and monkeys, as well as from the liver and spleen in section (fatal) cases.

causes of yellow fever

main source and reservoir of infection in the form of yellow fever dzhunglevoy - wild animals (monkeys, possums, marsupials, rodents, etc.), while urban form - the man.

Infectious Source period can not be determined in animals, in humans, this period begins shortly before the onset of clinical signs of the disease lasts for 3-4 days.

carriers of the virus of yellow fever mosquito, both domestic and wild.Mosquitoes become infectious by 9 - 12 days after bloodsucking at ambient temperature to 25 ° C, 7 days at 30 degrees, after 4 days at 37 degrees at a temperature below 18 degrees mosquito loses the ability to transmit the virus.Accordingly, the hotter the climate, the faster the mosquito becomes infectious.In the absence of mosquitoes sick person is not contagious to others.The incidence increases after the rainy season when the mosquito population increases.

pathogen transmission mechanism - transmissible, carriers in the urban centers of - the mosquitoes Aedes aegypti, in the jungle, some other members of this genus.Possible contact and parenteral routes of transmission (through infected blood).Cases of laboratory contamination.

yellow fever vectors

natural susceptibility of people high, suffer both children and adults.In endemic countries, the local population has latent (asymptomatic) immunization small doses of the virus, they do not become ill and develop immunity.

after previous infection in the event of a favorable outcome of developing a strong immunity (up to 6 years or more).

As the disease progresses?

enters the lymph nodes close to the site of the bite (regional), which is its reproduction (in humans, the incubation period - 3-6 days) When the virus through the bite of the lymphatic system.

Transmissible way of infection with yellow fever

virus then hematogenically (through the blood) spread throughout the body and cause damage to the liver, spleen, kidney, bone, and brain (the patient during viremia - 3-5 days).Noteworthy favorite defeat virus vessels of these bodies, the result of which will increase in vascular permeability of the capillary bed.In addition, the developing cell damage: degeneration and necrosis of liver cells, kidney.Unconditional and heavy is the internal hemorrhagic syndrome (hemorrhage in the internal organs - the spleen, heart, brain, intestine, lungs).It is obvious that such severe lesions often are not compatible with life.

Symptoms of yellow fever

incubation period (from infection to onset of symptoms) lasts an average of 3 to 6-days.Typical for yellow fever is a kind of "double-wavelength" character with the 3 periods:

1) initial;
2) remission (improvement);
3) during the venous stasis (sharp deterioration).

also secrete several forms of severity: mild, moderate, and severe lightning.

1. Basic (feverish) period lasts 3-4 days.The disease begins acutely, characterized by a sharp rise in temperature to a maximum level of up to 40 ° on the first day of illness.Patients worried chills, severe headache, muscle pain in the back and limbs, vomiting, often repeated, thirst, general weakness.Pulse is speeded up to 130 per minute, blood pressure normal, heart sounds are muffled.For patients with yellow fever in the initial period is characterized by the so-called "amarilnaya Mask" (redness of the face, neck, or eyes konyuktiv - vascular injection, edema of the eyelids, puffy face, swollen lips).

Patients annoying glare disturbs sleep disorders.Patients irritable skin is hot and dry.Often there is no criticism to his condition, but there is fear and euphoria.The liver and spleen increase in size, painful on palpation.In peripheral blood - neutropenia and lymphopenia, ESR is not enlarged.In the urine - proteinuria.

On the 3rd day of illness appears jaundice (yellowing of the sclera eyes first, then the mouth, eyelids and skin).

Jaundice with yellow fever

Quickly join hemodynamic instability (blood pressure falls, the skin becomes bluish tint).The patient gets worse: there are initial manifestations of hemorrhagic syndrome - bleeding gums, nosebleeds, blood in the stool and vomit.The patient greatly slows the pulse.In severe disease in this period, the patient may die.

2. At a less severe disease occurs remission (4-5 hours of onset): the temperature decreases, the condition is improving, stops vomiting.This period can last from several hours to days and in mild patient recovers.More frequently observed severe and comes 3rd period.

3. venous stasis period (lasting 3-4 days). temperature rises again, jaundice increases, as well as become more severe hemorrhagic symptoms: nasal, uterine, gastrointestinal hemorrhage, major hemorrhage appear on the skin.

yellow fever patients

rapidly developing acute renal failure with marked albuminuria (protein in the urine), oliguria (decreased urine output), it is possible anuria (absence of urine output).Blood pressure falls, heart sounds are muffled, pulse 40 beats per minute, beats, can collapse.Dimensions of the liver increased, it becomes dense, sharply painful on palpation of the liver capsule tension.At the biochemical examination of blood: increase performance of direct and indirect bilirubin, ALT, decreased white blood cell count up to 1.5-2.5 thousand per 1 L, marked neutropenia and lymphopenia..Slows blood clotting, increased erythrocyte sedimentation rate.These changes are most typical for the 6-7 day of illness.This critical period for the patient, the amount of protein in the urine increased to 10 g / l appear grainy and hyaline cylinders.

lethal outcome occurs in 50% of cases, often due to acute renal failure with the development of uremic coma (cerebral edema, loss of consciousness), and toxic encephalitis, sometimes by hepatic coma, or cardiovascular disease (myocarditis).

With a favorable course of the disease with a 8-9 day illness general condition gradually improved, there comes a period of convalescence (convalescence), laboratory parameters are normalized.A small weakness in the form of a residual phenomenon persists for weeks.

complications of yellow fever

Complications of yellow fever are: pneumonia, kidney abscess, encephalitis, can be soft tissue gangrene, possibly fatal.

When to see a doctor?

If you are in an endemic country or arrived recently (3-6 days) from it, the appearance of the first symptoms - high temperature for the first day of illness should you get to see a doctor.No self-medication is not allowed!Only urgent hospitalization!

diagnosis of yellow fever

preliminary diagnosis is based on:

1) The arrival or stay in the endemic region (Africa and South America) - tropical and subtropical;
2) symptoms of the disease ( "saddle" or "two-wave" temperature curve, hemorrhagic syndrome, jaundice, kidney disease, liver and spleen);
3) Laboratory data: (in biochemistry - increased bilirubin, ALT, AST, urea, creatinine, in the general analysis of blood - depression shoots hematopoiesis - a decrease of leukocytes, neutrophils, lymphocytes, decreased platelet count, ESR acceleration, in the urine - a protein cylinders,erythrocytes) and other.

two-wave temperature curve for yellow fever

final diagnosis is confirmed by specific laboratory data at
study of blood on the suspect yellow fever patient taken to 3-4go day of illness.
1) biological method (by intracerebral infection of infants or young white mice).
2) Rapid tests based on antigen display - is carried out by ELISA, results after 3 h.
3) Of the serological tests used RN, CFT, HI, Phragmites, put paired sera taken at the end of the first week of illness, and after 2-3 days.
4) When a lethal outcome studied histologically liver where identified pockets of submassive and massive necrosis of liver lobules and acidophilus Kaunsilmena calf.

Yellow fever differentiate influenza, viral hepatitis, malaria, tropical, icteric form of leptospirosis, dengue fever, tick-borne relapsing fever, Crimean-Congo hemorrhagic fever, a hemorrhagic fevers Lassa, Ebola, Marburg.

Treatment of yellow fever

1. Organizational-regime activities.Hospitalization of patients in the hospital and bed rest!Violation of this clause could cost a person their life.Lacto-vegetarian diet with a complex of vitamins (C, B).
2. causal (antiviral) therapy is not.
3. Pathogenetic and symptomatic treatment:
- detoxification (glucose-saline solutions, albumin solutions);
- prevention and treatment of hemorrhagic syndrome (prednisolone, aminocaproic acid, colloidal solutions, for a blood transfusion if indicated);
- in renal failure (dehydration, stimulation of diuresis, hemodialysis if indicated);
- with the defeat of the liver (detoxification of the body - Gepasol, gepatoprotektory, glucose, etc.)
- Layering secondary bacterial infections prescribe antibiotics.

Prevention of yellow fever

Preventive measures are aimed at preventing the introduction of infection from abroad.

1) Carry out the destruction of mosquitoes and their breeding places, protecting them from the premises and the use of personal protective equipment
.
2) As a means of immunization using single immunization with a live attenuated vaccine
, mainly from the strain 17-D (0,5 ml subcutaneously at a 1:10 dilution), persons between the ages of 9 months.and older, living in endemic areas, or intending to visit them, with a booster after 10 years.Immunity is produced from 10 days after immunization and 1 - after revaccination.In Russia, used a Russian-made vaccine that meets WHO standards.Abroad appointed vaccine "Stamar Pasteur" proizvodstvava "Aventis Pasteur" (France).All vaccinated
issued an international certificate of vaccination or revaccination against yellow fever, which is individual and filled in English and French.The certificate becomes valid from the 10th day after vaccination and for 10 years.

Vaccination is recommended for people traveling to countries: Angola, Argentina, Benin, Guinea-Bissau, Bolivia, Brazil, Burkina Faso, Burundi, Venezuela, Gabon, Gambia, Ghana, Guinea, Guana, Democratic Republic of Congo, Cameroon, Kenya, Colombia, Congo, Côte d'Ivoire, Liberia, Mali, Mauritania, Niger, Nigeria, Panama, Paraguay, Peru, Rwanda, Senegal, Sudan, Suriname, Sera Leone, Togo, Uganda, French Guiana, Central African Republic, Chad,Ecuador, Equatorial Guinea, Ethiopia, South Sudan.

infectious disease doctor Bykov NI