(TRENTON) – A 15-year-old Atlantic County mare has been identified as a confirmed case of Eastern Equine Encephalitis (EEE), a serious mosquito-borne illness in horses, in New Jersey. 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, and the horse passed away as a result of the disease on August 3, 2024. The horse was recently vaccinated on July 29, 2024, but prior vaccination history is unknown.

EEE causes inflammation of the brain tissue and has a significantly higher risk of death in horses than West Nile Virus infection.  West Nile Virus is a viral disease that affects a horse’s neurological system.  The 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 5-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.”

For more information about EEE in horses, visit the New Jersey Department of Agriculture website at: http://www.nj.gov/agriculture/divisions/ah/diseases/diseaseworksheets.html

EEE and West Nile virus, like other viral diseases affecting a horse’s neurological system, must be reported to the State Veterinarian at 609-671-6400 within 48 hours of diagnosis. The New Jersey Animal Health Diagnostic Laboratory is available to assist with EEE and WNV testing and can be reached at 609-406-6999 or via email – jerseyvetlab@ag.nj.gov. Learn more about the NJ Animal Health Diagnostic lab at www.jerseyvetlab.nj.gov. 

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