Ensuring that all horses get their spring vaccinations is the best way for horse owners to protect their horses and do their part to prevent Eastern equine encephalitis, West Nile Virus, and Western equine encephalitis. Unvaccinated horses may be at serious risk of contracting these mosquito-borne illnesses especially in areas where the diseases may not be common..
The risk of exposure and geographic distribution of EEE varies from year to year with changes in distribution of insect vectors and reservoirs important to the natural ecology of the virus.
Alhough Eastern equine encephalitis typically appears in the southern and eastern parts of the country, Michigan and California reported multiple cases of the disease. Eastern equine encephalitis is considered to be endemic in all areas of North America by the American Association of Equine Practitioners, and all horses should be vaccinated against it.