Flaviviruses (Yellow Fever, Tick-Borne Encephalitis, Dengue, Japanese Encephalitis, West Nile Virus)
7 topics with concise reviews: definitions, key facts, and class questions.
This section is dedicated to the family Flaviviridae, which consists of enveloped, RNA-containing arboviruses transmitted primarily through the bites of blood-sucking arthropods (ticks and mosquitoes). These pathogens cause severe neuroinfections and hemorrhagic fevers, requiring a clear understanding of their epidemiology and pathogenesis.
Here you will find materials on key representatives of the family. You will study the properties of yellow fever, dengue, Omsk hemorrhagic fever, and West Nile viruses, as well as the causative agents of tick-borne and Japanese encephalitis. The section structure covers viral morphology, transmission mechanisms, replication cycles, and the basics of laboratory diagnostics.
During classes and exams, instructors most often emphasize the natural focal character of these infections and the role of vectors. Be sure to pay attention to rapid diagnostic methods (PCR) and serology (ELISA), as well as specific prophylaxis algorithms—primarily vaccines against yellow fever and tick-borne encephalitis.
Which serological reaction is considered the most specific for the identification of flaviviruses?
Neutralization test (NT). Unlike the complement fixation test (CFT) and hemagglutination inhibition test (HI), which can yield cross-reactions within the group, the neutralization test allows for the precise differentiation of even closely related arbovirus species.
What is the vector of the virus in the urban form of the disease?
The vector is represented by synanthropic mosquitoes of the species Aedes aegypti. They transmit the pathogen via an anthroponotic chain from a sick person to a healthy one.
Can one contract tick-borne encephalitis without a tick bite?
Yes. Infection is possible through the consumption of raw milk from infected goats or sheep (alimentary route), as well as when the virus enters microtraumas in the skin from crushing a tick.
What is the main difference between Omsk hemorrhagic fever virus and tick-borne encephalitis virus?
Despite close antigenic and biological relatedness, the Omsk hemorrhagic fever virus does not exhibit pronounced neurotropic properties.
Why is dengue fever referred to as the "dandy" fever?
The name comes from a distorted version of the English word dandy. Due to severe muscle and joint pain, patients change their posture and develop a characteristic stiff or swaggering gait.
Who first discovered the Japanese encephalitis virus and how?
The virus was isolated in 1933 by the Japanese researcher M. Hayashi. To achieve this, he infected a laboratory monkey with a brain suspension from individuals who died during an encephalitis outbreak.
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