Venezuelan equine encephalitis

Definition

A mosquito-borne viral disease caused by Venezuelan equine encephalitis virus (family Togaviridae, genus Alphavirus) that affects equids and humans. In horses, donkeys, and zebras, VEE produces acute encephalomyelitis with high mortality; in humans, infection ranges from mild febrile illness to severe neurological disease, particularly in children and immunocompromised individuals. The virus is maintained in enzootic cycles involving forest-dwelling mosquitoes (primarily Culex (Melanoconion) spp.) and small mammals, with epizootic strains emerging periodically to cause explosive outbreaks in equids and humans transmitted by floodwater Aedes and Psorophora mosquitoes.

Etymology

From Venezuela (where first isolated, 1938), Latin equus (horse), and Greek enkephalos (brain) + -itis (inflammation)

Example

During the 1969–1972 epizootic, Venezuelan equine encephalitis spread from Guatemala through Mexico and into Texas, with Aedes taeniorhynchus and other salt-marsh mosquitoes implicated in coastal transmission to horses and humans.

Synonyms

• Venezuelan equine encephalomyelitis
• VEE

Related Terms

• Arbovirus
• alphavirus
• mosquito-borne disease
• equine encephalitis
• Eastern equine encephalitis
• western equine encephalitis
• enzootic cycle
• Epizootic
• viral emergence
• vector competence
• Aedes
• Culex Melanoconion

Usage Notes

Often abbreviated VEE in scientific and veterinary literature. Distinguished from eastern equine encephalitis (EEE) and western equine encephalitis (WEE) by geographic distribution, vector associations, and viral serocomplex. The term 'encephalomyelitis' is sometimes preferred in veterinary contexts to emphasize spinal cord involvement. Enzootic and epizootic strains differ in virulence to equids and humans; only epizootic strains cause major equine outbreaks. Surveillance focuses on mosquito vectors and sentinel equids.