Eastern equine encephalitis virus

Eastern equine encephalitis virus (EEEV) is a single-stranded, positive-sense RNA virus. It is most commonly seen as an infection of horses, however it sporadically affects species of poultry. The disease occurs primarily in the eastern parts of North America, throughout Central America and the Caribbean, and in eastern parts of South America. In the United States, EEE has been identified in most states east of the Mississippi River, as well as Louisiana and Texas; it occurs most often in Atlantic seaboard states and Gulf Coast states.

Outbreaks generally occur in late summer and fall as a consequence of increasing numbers of mosquito vectors. The virus is maintained in nature through a bird—mosquito cycle. Wild birds from the Passeriforme family, are the principal vertebrate hosts of EEE virus. These birds rarely become ill but serve as maintenance and amplifying hosts for the virus in the transmission cycle.

Hosts: EEEV is capable of infecting a wide range of animals, including mammals, birds, reptiles, and amphibians



  • Order: Martellivirales
  • Family: Togaviridae
  • Genus: Alphavirus


  • horses
  • wild birds
  • pheasants
  • mosquitoes
  • birds