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Eastern Equine Encephalitis - Click to enlarge

December 26, 2023 
PO Box 330
Trenton, New Jersey 08625-0330

Jeff Wolfe
P: (609) 633-2954
C: (609) 433-1785


Third Eastern Equine Encephalitis Case for New Jersey in 2023

(TRENTON) – A third confirmed case of Eastern Equine Encephalitis (EEE) was detected in an unvaccinated 28-year-old Grade breed mare in Ocean County. Depression, front and rear ataxia, disorientation and falling were among the reported clinical signs, and the horse was humanely euthanized due to clinical deterioration. EEE was diagnosed in Gloucester and Salem Counties in September and October 2023.

In general, most regions in New Jersey have a reported mosquito population this season to be near the 5-year average. This case occurred beyond the expected mosquito-borne disease season for New Jersey. The horse had no recent travel history, indicating that the disease was transmitted within the state. Based off the clinical history, it is possible that exposure to EEE occurred during a period of warmer than average temperatures experienced in the area at the end of mosquito season.

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 Assistant Secretary of Agriculture Joseph Atchison III 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:

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 – Learn more about the NJ Animal Health Diagnostic lab at


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