Last week the Ohio Department of Agriculture confirmed cases of Eastern Equine Encephalitis (EEE) in two horses that died on a farm in Mercer County. This is the first incident of EEE in Ohio since an outbreak in 1991 in Wayne and Holmes counties. At this time, there are no known human illnesses associated with this confirmation.
EEE is a viral disease that affects the central nervous system and is transmitted to horses by infected mosquitoes. Signs of the virus include fever, listlessness, stumbling, circling, coma and usually death. The disease is fatal in horses in 90% of cases. Humans and horses can only contract the disease from mosquitoes, and not from each other, but because illness in horses usually precedes illness in people by days to weeks, reports of equine illness serves as an early warning for the human population.
The Ohio Department of Health urges Ohioans to take steps to avoid mosquito bites, such as wearing light-colored long pants and long-sleeved shirts as well as socks and shoes. In addition, to avoid mosquito bites for both animals and humans, the Ohio Departments of Agriculture and Health recommend insect repellants be used according to label directions. Mosquitoes can be active until the first frost and will stay infected, and capable of transmitting viruses, as long as they live.
An effective equine vaccine exists for EEE, but is not always used. Earlier this year, Florida Agriculture and Consumer Services Commissioner Charles Bronson urged horse owners to get their animals vaccinated as the number of Eastern Equine Encephalitis cases quadrupled over the prior two years. In Florida there have now been 89 confirmed cases in 2010. The next most affected state is Michigan, where there have been 45 confirmed cases in horses and 2 confirmed cases in humans so far in 2010.