Eastern equine encephalitis (EEE) is a viral disease characterized by inflammation of the brain and spinal cord. Wild birds are a major reservoir for EEE infection, and mosquitoes that feed on them may transmit the virus to horses, humans, and other animals.
Transmission is primarily through the bites of the Culiseta melanura mosquito, and the illness is most common in the southern United States (but other mosquito species are also capable of transmitting the virus). The amount of virus in the blood of sick horses and humans is too low for them to spread the disease. As a result, sick people do not need to be isolated. Because of the disease’s high fatality rate in horses and people, it is regarded as one of the most deadly mosquito-borne illnesses in the United States.