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Yellow fever

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Yellow fever

Yellow fever (amarillez) — the acute arbovirusny illness of tropical countries which is characterized by a two-phase current, fever, a heavy hemorrhagic syndrome, jaundice, a nephropathy. Treats especially dangerous quarantine diseases.

Etiology. The activator — a virus which patogenen also for monkeys and white mice, termolabilen, is sensitive to usual disinfectants. When drying and freezing it remains over a year. The virus is cultivated in cultures of cells. Long cultivation received the avirulent strains used as a vaccine.

Epidemiology. Distinguish two types of the centers of yellow fever. Endemic (natural) the centers of yellow fever of the jungle (rural type) are primary. An infection source — monkeys, ascigerous hedgehogs, anteaters and other animals. Carriers — mosquitoes which can infect also the person. In settlements the epidemic centers of yellow fever of city type where an infection source — the sick person form. Mosquitoes — carriers of yellow fever of city type differ from carriers of yellow fever of the jungle. The activator — the same virus. Depending on ambient temperature the mosquito is capable to transmit a virus in 9 — 12 days (till 30 days) after infection and to keep the infecting ability for life.

Pathogeny. The virus gets into an organism at a sting the infected mosquito. On lymphatic ways the activator gets to lymph nodes where breeds. Since the end of an incubation interval a blood flow it extends on an organism, affecting a liver, a spleen, kidneys, marrow. In a liver Kaunsilmen's little bodies are typical. The virusemia proceeds 3 — 5 days.

Clinic. Incubation interval of 3 — 6 days. The clinic is characterized by two-staging of a current. The initial stage (a hyperemia stage) - an illness begins suddenly with a tremendous fever, temperature increase to 39 — 41 °C. There are a severe headache, pain in muscles of a back and extremities, nausea, vomiting. Outward is characteristic: icteric coloring of skin, a face red, bloated, eyelids are edematous. The photophobia, tachycardia are noted. In blood a leukopenia. The state every day worsens. The prostration, excitement, nonsense are possible. With 4 — the 5th day temperature decreases, the state improves a little (the remission period).

In several hours or 1 — 2 day temperature increases again, the general state sharply worsens — there comes the reactive period: the active hyperemia is replaced by venous stagnation (a stage of a staz). A pale face, with a cyanotic shade. There are jaundice, a moderate hepatolienal syndrome. Hemorrhagic diathesis is expressed; hemorrhagic rash, bleeding of mucous membranes, gastrointestinal, pulmonary bleedings, hamaturia. The oliguria, an anury develops. The albuminuria, a cylindruria are expressed. Tachycardia is replaced by bradycardia (Fazhe's symptom). In hard cases the collapse, toxic encephalitis are possible, uraemic or the hepatic coma is more rare. A lethality from 5 — 10% to 15 — 20%, and during epidemic flashes — to 50 — 60%. Lungs, the erased illness forms are possible.

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