Equine Encephalitis Viruses & Chikungunya Virus (Togaviridae)

The Togaviridae family, which includes viral species in the Alphavirus genus, are positive-sense, enveloped RNA viruses. Alphaviruses within this family exhibit an icosahedral capsid. Many are arboviruses transmitted by arthropods. Notably, the equine encephalitides (EEEV, WEEV, VEEV) affect horses and humans, with transmission occurring through mosquitoes. Alphaviruses causing equine encephalitides often maintain an animal reservoir, including birds. Eastern equine encephalitis virus (EEEV) is primarily concentrated along the eastern U.S. coastline and is more prevalent during the summertime. Western equine encephalitis virus (WEEV) affects western and southwestern parts of the U.S Neuroinvasive EEEV infections can lead to meningitis and encephalitis, carrying a high risk of death or long-term morbidity. Western equine encephalitis virus (WEEV) particularly threatens infants, who are at higher risk for severe encephalitis. Venezuelan equine encephalitis virus (VEEV) is another Alphavirus, with neuroinvasive VEEV infections being more common in children. Chikungunya virus (CHIKV), also within this family, is transmitted by Aedes aegypti mosquitoes and causes chikungunya fever. This virus is found worldwide due to global trade and can result in chronic arthralgias and arthritis, persisting for months to years.

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