Pathology of Eastern Equine Encephalitis

Dr Sampurna Roy MD

Eastern equine encephalitis (EEE) is an extremely rare but serious and often fatal infection that causes encephalitis or inflammation of the brain.

It is a mosquito-borne viral disease.

Eastern equine encephalitis virus is a member of the family Togaviridae, genus Alphavirus. 

Eastern equine encephalitis is encountered primarily in the eastern and north central United States and adjoining provinces of Canada.

The reservoir is birds. Horses and humans have "dead-end" infections.

Mosquitoes are vectors.

It takes from 3 to 10 days to develop symptoms of Eastern equine encephalitis after being bitten by an infected mosquito.

Epizootics among horses usually precede epidemics in humans.

Eastern equine encephalitis occurs primarily during summer in temperate zones.

Symptoms range from mild flu-like illness to Eastern equine encephalitis (inflammation of the brain), coma and death.

Approximately 30% of people with EEE die and many survivors have ongoing neurologic problems.

The diagnosis of Eastern equine encephalitis virus infection is serology, especially IgM testing of serum and cerebrospinal fluid.

PCR, histopathology with immunohistochemistry, and virus culture of autopsy tissues  are useful in fatal cases.

Visit related posts: Alphaviruses causing Encephalitis; Western equine encephalitis viruses; Venezuelan equine encephalitis viruses.

Further reading:

Clinical and neuroradiographic manifestations of eastern equine encephalitis

Eastern Equine Encephalitis

Eastern Equine Encephalitis

Genetic and antigenic diversity among eastern equine encephalitis viruses from North, Central, and South America.

Isolation of eastern equine encephalitis virus from Aedes albopictus in Florida

Antigenic variants of eastern equine encephalitis virus

Eastern Equine Encephalitis

Identification of monoclonal antibodies capable of differentiating antigenic varieties of eastern equine encephalitis viruses.