Western equine encephalitis

Synonyms and Related Keywords: Mosquito-borne

Epidemiology and Demographics
639 confirmed cases in the U.S. since 1964.

Risk Factors

 * Epidemic disease that is difficult to predict
 * Residents of endemic areas and visitors
 * Persons with outdoor work and recreational activities
 * Risk exposure increases as population expands into endemic areas
 * Unknown overwintering cycle

Pathophysiology & Etiology
Western equine encephalitis virus, member of the family Togaviridae, genus Alphavirus. Closely related to eastern and Venezuelan equine encephalitis viruses.

History and Symptoms
Symptoms range from mild flu-like illness to frank encephalitis, coma and death.

Treatment

 * No licensed vaccine for human use
 * No effective therapeutic drug

Primary Prevention

 * Control measures expensive
 * Limited financial support of surveillance and prevention

Cost-Effectiveness of Therapy

 * Total case costs range from $21,000 for transiently infected individuals to $3 million for severely infected individuals
 * Insecticide applications can cost as much as $1.4 million depending on the size of area treated

Suggested Reading and Key General References

 * http://www.cdc.gov/ncidod/dvbid/arbor/weefact.htm