ABSTRACT
Guides for Emergency Response: Biological Agent or Weapon: Viral Encephalitus AGENT: Venezuelan Equine Encephalitis (VEE) also includes Western and Eastern Equine Encephalitis (WEE and EEE). VEE consists of eight serologically distinct viruses belonging to the Venezuelan equine encephalitis complex that have been associated with human disease. Th e most important of these pathogens are designated subtype 1, variants A, B, and C. Such agents also cause severe disease in horses, mules, and donkeys. Natural infections are acquired by the bites of a wide variety of mosquitoes, and such animals serve as viremic (the presence of virus in the blood of a host) hosts and source of mosquito infection. In natural human epidemics, severe and oft en fatal encephalitis in horses, mules and donkeys always precedes that in humans. A biological warfare or terrorist attack with virus disseminated as an aerosol would cause human disease as a primary event. If horses, mules, and donkeys were present in the area, disease in these animals would occur simultaneously with human disease, while secondary spread by person-to-person contact occurs at a negligible rate. However, in an attack in an area populated by horses, mules, and donkeys with appropriate mosquito vectors (an organism that transmits a pathogen from one organism to another, as fl eas carry plague, mosquitoes carry VEE) could initiate an epizootic (an outbreak of a disease aff ecting many animals of one kind at the same time) epidemic. Children and the elderly are more susceptible to the VEE virus than the average adult; however, pregnant women might develop serious problems although most victims live through this disease.
