Eastern equine encephalomyelitis virus (EEEV) is an arbovirus belonging to the genus Alphavirus, family Togaviridae. It is primarily transmitted by the bite of infected mosquitoes, predominantly Culiseta melanura, which acquire the virus from the reservoir host, wild birds, particularly passerine (perching) birds. EEEV is known to cause severe cases of encephalitis in humans and horses, and occasionally affects other mammals such as emus and llamas.
The virus is typically endemic or sporadic in regions of North and South America, predominantly in the eastern and southeastern parts, including the United States. EEEV infection can result in two forms of the disease: systemic or encephalitic. In the systemic form, individuals display fever, headache, weakness, and muscle pain. This may progress to more severe symptoms such as vomiting, diarrhea, and disorientation. In the encephalitic form, the infection may further progress to cause inflammation of the brain, leading to seizures, coma, and ultimately, death in approximately 30-70% of severe cases.
There is no specific antiviral treatment available for EEEV infection in humans. Vaccination of horses is the primary approach to reduce the risk of infection in horses and indirectly protect humans by reducing the reservoir of the virus. Prevention measures for humans include personal protection against mosquito bites, such as using insect repellent, wearing protective clothing, and minimizing outdoor activities during peak mosquito activity. Surveillance and control of mosquito populations are also essential measures to minimize the risk of transmission.
