Eastern Equine Encephalitis in Georgia
Two horses from different farms in the Savannah, Georgia area have been diagnosed with eastern equine encephalitis (EEE). This is a severe neurological disease that can strike very quickly, and is fatal in up to 90% of cases. There is no specific treatment, and affected horses often deteriorate rapidly and dramatically. The virus that causes EEE is transmitted from birds to horses by the bites of infected mosquitoes, which makes it a seasonal disease. The risk of EEE is also heavily influence by geography, largely due to the distribution of mosquito species that effectively transmit the virus. Some areas have recurrent (and often major) problems with EEE, other areas (like Ontario) have few or no cases on a yearly basis, but can experiece small clusters of disease from time to time, and still other areas never see cases at all.
Identification of EEE is important for a few reasons. Obviously, it's relevant for horse health. It indicates that EEE virus is in the area and mosquitoes capable of transmitting it between birds and horses are also present. Horse owners need to be aware of the EEE history in their area when deciding whether or not to vaccinate against this deadly disease. On a seasonal basis, waiting until the first cases are diagnosed to vaccinate isn't a good plan, because there is always a delay from vaccination until peak immunity, and your horse could be infected before the vaccine is given or takes effect. EEE vaccination is best performed about one month prior to the at-risk period/season, with a booster six months later if the risk of exposure is still present (e.g. in southern areas were mosquitoes are present year-round).
Identification of EEE also has implications for human health. EEE can also infect people and cause very serious (and often fatal) disease. People cannot acquire EEE from horses, but hey are infected the same way: from the bite of an infected mosquito. A vaccine is not available for people so mosquito avoidance is critical. Identification of cases of EEE in the area should be a reminder to look at farm measures to reduce mosquiotes and decrease mosquito bites (more information on this is available in an earlier post about West Nile virus).
