In 1991, Ohio recorded its first outbreak of Eastern Equine Encephalitis among horses in southern Wayne and northern Holmes counties. Seventeen of nineteen affected horses died. This is of concern not only because of the health risk to horses, but EEE can also affect people. EEE Eastern Equine Encephalitis is caused by a virus that can infect horses, birds and man. It is transmitted by marsh breeding mosquitoes.
Outbreaks usually occur in the late summer and early fall when mosquitoes are most abundant.
Wild birds carry the EEE virus and serve as the main reservoir of infection for mosquitoes. The virus reproduces in the body of the mosquito and migrates to the salivary glands. The mosquito can transmit the disease when it bites a horse or human. People and horses are considered dead end hosts because they neither transmit the virus nor serve as reservoirs. About five days post-infection, horses begin to show fever and neurologic signs.