The Natural Occurrence of Venezuelan Equine Encephalitis in the United States

Naturally acquired Venezuelan equine encephalitis (VEE) has not been previously recognized in the United States, although VEE virus has been repeatedly isolated in Everglades National Park. In September, 1968, severe headache and feverishness suddenly developed in a 53-year-old woman living in Homestead, Florida. On admission the temperature was 105°F. Cerebrospinal-fluid findings indicated an aseptic-meningitis pattern. Electroencephalography showed diffuse disorganization. Hemagglutination-inhibition (HI) and complement-fixation antibodies to VEE virus rose in titer, but antibodies to other arboviruses or picornaviruses did not. A survey of 353 residents of the Homestead area revealed five to have VEE HI antibodies of 1:20 or higher and neutralizing antibodies of 2.0 logs or higher; one person had had recent illness. Since the Florida strain of VEE appears to be capable of causing disease in man, the occurrence of antibodies in persons living close to an urban area may have serious epidemiologic implications.