Eastern equine encephalitis virus infection

Eastern equine encephalitis virus infection is the most deadly encephalitic arbovirus infection in North America, with a case fatality rate of approximately 30%.

Occurs mainly in North America, around the eastern seaboard and Gulf Coast states, and is transmitted by mosquitoes.

Majority of patients remain asymptomatic after infection, and less than 5% of infected patients develop encephalitis or meningitis.

Diagnosis is based on clinical presentation and geographical clues. Confirmation of diagnosis is via serological testing. It is a notifiable condition.

There is no specific treatment; supportive care with management of specific symptoms, and close monitoring for complications, is recommended.

Eastern equine encephalitis virus (EEEV) is an alphavirus that is transmitted by the bite of infected mosquitoes.[1]Centers for Disease Control and Prevention. Eastern equine encephalitis virus: guidelines for eastern equine encephalitis virus surveillance and control. May 2024 [internet publication]. https://www.cdc.gov/eastern-equine-encephalitis/php/surveillance-and-control-guidelines/index.html ​ Humans infected with EEEV may be asymptomatic, or they may develop symptoms that resemble influenza or dengue fever (e.g., fever, malaise, headache, nausea) with or without neuroinvasive symptoms (e.g., altered mental status, seizures). Severe cases of infection are known as eastern equine encephalitis (EEE) and are extremely rare, but often fatal. The duration of acute illness is typically days to weeks depending on the severity.[1]Centers for Disease Control and Prevention. Eastern equine encephalitis virus: guidelines for eastern equine encephalitis virus surveillance and control. May 2024 [internet publication]. https://www.cdc.gov/eastern-equine-encephalitis/php/surveillance-and-control-guidelines/index.html