HWN Suggests

The continued threat of emerging flaviviruses

Flaviviruses are single-stranded RNA viruses vectored principally by arthropods that cause severe illnesses in humans. The extensive global spread and epidemic transmission of flaviviruses during the last seven decades has been remarkable. The mosquito-borne dengue viruses (DENV) infect an estimated 400 million humans each year; more than a quarter of the world’s population lives in areas where DENV is now endemic. By comparison, only sporadic DENV epidemics were documented before the Second World War. The introductions of West Nile (WNV) and Zika (ZIKV) viruses into the Western Hemisphere was followed by rapid geographical spread, large numbers of human infections and considerable morbidity.

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Featured

 The Viral Most Wanted: The Flavivirus Family

It's certainly a big family, with 70 known members, and possibly more relatives yet to be discovered. Prime Suspects Among the most dangerous and deadly members of the Flavivirus Family are Yellow Fever virus, Dengue virus, Zika virus, West Nile virus, Japanese Encephalitis virus, Tick-Borne Encephalitis virus, Kyasanur Forest virus, Alkhurma virus and Omsk virus. Hepatitis C is also a Flavivirus and the only one in the family that is not vector-borne, so it stands out from the rest of the family as an exception.

Articles of Interest

Flavivirus Threats Persist

WRAIR has been researching flaviviruses, a family of viruses that includes yellow fever, Japanese encephalitis, dengue, West Nile and Zika viruses, for over a century, beginning in the 1890s when Major Walter Reed helped prove that yellow fever is spread by the Aedes aegypti mosquito. Spread primarily by ticks and mosquitoes, these viruses can cause a wide range of illnesses manifesting in diverse symptoms.

Flavivirus and its Threat

Flaviviruses are transmitted primarily by arthropods. Most areas of the globe are endemic for at least one flavivirus, putting billions of the population at risk for infections. Flaviviruses are now globally distributed and infect up to 400 million people annually.

Flaviviruses

The majority of the viruses in the genus flavivirus are arboviruses—transmitted between mammalian hosts by an invertebrate vector (mosquitoes and ticks). Virus replication takes place in both the vertebrate host and the insect vector. In the case of yellow fever and dengue viruses, these are maintained in the wild by transmission from primates to mosquitoes, and back to primates. Humans are infected as accidental event when intruding into this natural ecosystem. Dengue virus has evolved along with the expansion of major conurbations to the extent that some experts argue a sylvatic cycle through an animal reservoir is no longer necessary for its endemicity.

Flaviviruses and the Central Nervous System: Revisiting Neuropathological Concepts

Flaviviruses are major emerging human pathogens on a global scale. Some flaviviruses can infect the central nervous system of the host and therefore are regarded as neurotropic. The most clinically relevant classical neurotropic flaviviruses include Japanese encephalitis virus, West Nile virus, and tick-borne encephalitis virus.

Mosquito-Borne Flaviviruses and Current Therapeutic Advances

Mosquito-borne flavivirus infections affect approximately 400 million people worldwide each year and are global threats to public health. The common diseases caused by such flaviviruses include West Nile, yellow fever, dengue, Zika infection and Japanese encephalitis, which may result in severe symptoms and disorders of multiple organs or even fatal outcomes. Till now, no specific antiviral agents are commercially available for the treatment of the diseases.

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ViralZone

Flavivirus is a genus of ssRNA+ viruses in the Flaviviridae family that infect vertebrates and are transmitted by arthropods (arbovirus). In humans, these viruses can cause fevers with variable symptoms.