A 15-year-old mare in Atlantic County, New Jersey, has been confirmed as a case of Eastern Equine Encephalitis (EEE), marking the first reported instance of the disease in a New Jersey horse for 2024. The horse exhibited symptoms such as fever, ataxia, and an inability to rise before succumbing to the illness on August 3, 2024. Despite being vaccinated on July 29, 2024, the mare’s prior vaccination history remains unknown.
EEE is a severe mosquito-borne disease that causes brain inflammation and poses a higher mortality risk in horses compared to West Nile Virus (WNV). Both diseases are transmitted through mosquito bites and involve a virus cycle between birds and mosquitoes. Horses and humans are considered “dead-end” hosts for EEE, meaning they do not significantly contribute to human infection risk.
In New Jersey, mosquito populations are generally near their five-year average. This year, Cape May County detected its first EEE-positive mosquito pool. Similar findings have been reported in Morris and Union counties. Livestock owners are urged to vaccinate against WNV, EEE, and other mosquito-borne illnesses using commercially available equine vaccines.
New Jersey Secretary of Agriculture Ed Wengryn emphasized the importance of vaccination: “We continue to encourage horse owners to be vigilant in vaccinating their animals against these diseases spread by mosquitoes,” he stated. “Vaccinated animals are much less likely to contract deadly diseases such as EEE and West Nile Virus.”
