Changes

====Epidemiology====

====Epidemiology====

Disease associated with EEE, WEE and VEE is largely restricted to the Western Hemisphere, ranging from temperate to desert climates.  Transfer is via '''vector''': mostly through '''[[Culicidae|mosquito salivary transfer]]'''.  WEE and VEE may also be transmitted via secretions.  Disease amplification occurs during the viraemic phase which lasts until nervous signs develop.  Amplification from horses is unlikely with EEE and WEE but occurs with VEE in association with a relatively high viraemia.  Zoonotic spread had been noted with VEE but is unlikely for the other two serotypes.

Disease associated with EEE, WEE and VEE is largely restricted to the Western Hemisphere, ranging from temperate to desert climates.  EEE in the United States is mainly seen in the Southeastern United States but has been detected in all states east of the Mississippi River and some Western states.  Large outbreaks of WEE have been described in California and other Western states but the incidence of clinical disease in these areas has experienced a dramatic decrease. The reason for this unknown but may be due to geographical variation in virulence.  Equine disease associated with WEE is rare on the Eastern seaboard ofthe United States.  VEE  virus is a very important human andveterinary pathogen in the Western Hemipshoere that can cause large outbreaks of disease in humans and horses over large geopgrahic areas. Transfer is via '''vector''': mostly through '''[[Culicidae|mosquito salivary transfer]]'''.  WEE and VEE may also be transmitted via secretions.  Disease amplification occurs during the viraemic phase which lasts until nervous signs develop.  Amplification from horses is unlikely with EEE and WEE but occurs with VEE in association with a relatively high viraemia.  Zoonotic spread had been noted with VEE but is unlikely for the other two serotypes.

====Pathogenesis====

====Pathogenesis====