Venezuelan Equine Encephalitis (VEE)

Signs and Symptoms

Venezuelan Equine Encephalitis (VEE) is a viral infection transmitted from horses to human by mosquitoes. It is not directly contagious from horses to humans.

Incubation period 1-6 days. Acute systemic fever illness with encephalitis developing in a small percentage (4% children; < 1% adults). Generalized malaise, spiking fevers, chills, severe headache, painful sensitivity to light, and muscle pain for 24-72 hours. Nausea, vomiting, cough, sore throat, and diarrhea may follow. Full recovery takes 1-2 weeks. The incidence of central nervous system (CNS) disease and mortality would be much higher after a bioterrorism attack.

Diagnosis

Physical findings are non-specific. The white-blood cell count may be high or low. Virus isolation may be made from serum, and in some cases throat-swab specimens. Blood serum sample indicates recent infection.

Therapy

Treatment is supportive only. Treat uncomplicated VEE infections with analgesics (aspirin) to relieve headache and muscle pain. Patients who develop encephalitis may require anticonvulsants and intensive supportive care to maintain fluid and electrolyte balance, ensure adequate ventilation, and avoid complicating secondary bacterial infections.

Preventative Measures

A live, attenuated vaccine is available as an investigational new drug. A second, formalin-inactivated, killed vaccine is available for boosting antibodies in those initially receiving the first vaccine.