Pathology of Venezuelan Equine Encephalitis

Dr Sampurna Roy MD

Venezuelan equine encephalitis is a mosquito-borne viral infection that can cause severe encephalitis in horses and humans.

Infection is caused by Venezuelan equine encephalitis virus (VEEV), a  single-stranded RNA virus (family: Togaviridae; genus: Alphavirus ).

This disease is encountered principally in Venezuela, Colombia, Central America, Mexico, and the southwestern United States.

Rodents, many other mammals, and birds are the reservoir.Horses and humans have "dead-end" infections. Vectors are mosquitoes.

This acute viral disease occurs throughout the year.

Clinical presentations:

Influenza-like manifestations, abrupt onset of severe headache, chills, fever, myalgia, retro-orbital pain, nausea and vomiting, conjunctival and pharyngeal injection.

Most cases are mild with symptoms lasting for 3 - 5 days.

Some cases have diphasic fever.

Central Nervous System involvement:

There is encephalitis with disorientation, convulsions, paralysis, coma and death.

In many cases convulsions are often seen in children.

Abortions and fetal deaths occur in pregnant women infected with Venezuelan equine encephalitis virus.