YELLOW FEVER: EPIDEMIOLOGY, CLINIC, DIAGNOSTICS AND PREVENTION

Abstract

The aim of the work is to summarize the data on etiology, epidemiological features, clinical manifestations and laboratory diagnostics of yellow fever (YF), to submit the main recommendations of the WHO and the CDC in relation to its prevention and treatment.

The most recent data about YF, the peculiarities of its distribution are given. The YF virus (YFV) belongs to the Flavivirus family. The main reservoir of the pathogen in the nature is monkeys, additional – perhaps hedgehogs, marsupials, rodents, in which the infection duration can be latent. YFV gets into the person by biting an infected mosquito. The disease is registered in tropical areas of Africa and Central and South America. The natural epidemiology of YF on both continents – is the circulation of the virus between forest mosquitoes and wild primates. The transmission to a human occurs in forest (jungle, rural), intermediate and urban focuses. The urban transmission cycle is the most dangerous epidemiologically, which is implemented among non-immune people, as a result of the infected persons’ movement, or by accidently transporting of the infected mosquitoes. The severe clinical course and complications testify a special danger of this disease for humanity. The incubation period is usually 3–6 days, it can rarely reach 10 days. Typically, there are three periods of illness: an initial febrile, a period of remission with decrease of body temperature and a period of venous stasis. Mortality is 5–10 %, during the epidemic – up to 60 % and above. For YF light, abortive forms of the disease without jaundice and hemorrhagic syndrome are also possible. For the diagnosis verification within 5 days from the onset of symptoms, a polymerase chain reaction with reverse transcription and serological diagnosis (ELISA) are used. An effective etiotropic method of treatment has not yet been developed, only pathogenetic remedies are used. Currently, the only way to fight this infection, according to WHO and CDC recommendations, is immunization. Vaccinations should be done at least 10 days before travel in the endemic area. Employees of specialized laboratories in the risk group of infection and must be vaccinated. Since July 11, 2016, the WHO has decided to exclude re-vaccination, because a single dose provides lifelong immunity.