An Atlantic County mare who was vaccinated for Eastern Equine Encephalitis in July died six days later from the effects of the mosquito-borne illness. It is the first reported case of EEE for a New Jersey horse in 2024. Fever, front and rear ataxia and inability to rise were among the reported clinical signs in the affected horse.
EEE causes inflammation of the brain tissue and has a significantly higher risk of death in horses than West Nile Virus infection, a viral disease that affects a horse’s neurological system. Both diseases are transmitted by a mosquito bite. The virus cycles between birds and mosquitoes, with horses and humans being incidental hosts. EEE infections in horses are not a significant risk factor for human infection because horses (like humans) are “dead-end” hosts for the virus.
In general, most regions in New Jersey have a reported mosquito population near the five-year average. The first EEE positive mosquito pool was detected in Cape May County this year (https://www.nj.gov/health/cd/statistics/arboviral-stats/). EEE positive mosquito pools have also been found in Morris and Union counties. Livestock owners are strongly encouraged to vaccinate against WNV, EEE, and other mosquito-borne diseases. Effective equine vaccines for EEE and WNV are available commercially. Horse owners should contact their veterinarians if their horses are not up to date on their vaccinations against both EEE and WNV.
“We continue to encourage horse owners to be vigilant in vaccinating their animals against these diseases spread by mosquitoes,” New Jersey Secretary of Agriculture Ed Wengryn said.
“Vaccinated animals are much less likely to contract deadly diseases such as EEE and West Nile Virus.”