CLINICAL FEATURES

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

ETIOLOGIC AGENT

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

INCIDENCE

• 639 confirmed cases in the U.S. since 1964

SEQUELAE

• Mild to severe neurologic deficits in survivors

COSTS

• 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

TRANSMISSION

• Mosquito-borne

RISK GROUPS

• Residents of endemic areas and visitors
• Persons with outdoor work and recreational activities

SURVEILLANCE

• National Notifiable Diseases Surveillance System

TRENDS

• Epidemic disease that is difficult to predict
• Risk exposure increases as population expands into endemic areas

CHALLENGES

• No licensed vaccine for human use
• No effective therapeutic drug
• Unknown overwintering cycle
• Control measures expensive
• Limited financial support of surveillance and prevention

OPPORTUNITIES

• Mosquito control
• Education of health-care workers and the public
• Integrated State and Federal prevention efforts
• Vaccine development
• Therapeutic development

RESEARCH PRIORITIES

• Improve predictive capabilities
• Develop and evaluate vaccines
• Develop and evaluate therapeutics
• Improve diagnostic and virus detection tests