With October only a few days away, EEE remains a threat in the Bay State.

That’s the message from health officials after another horse in Massachusetts tested positive for Eastern Equine Encephalitis.

Four people in the state have been infected with the rare but serious and potentially fatal disease during this busy year of mosquito-borne illnesses. A man in New Hampshire died from EEE.

The Massachusetts Department of Public Health on Thursday announced a third confirmed case of EEE in a horse this year. The horse was exposed to EEE in Carver, an area in Plymouth County that’s already at high risk for EEE.

“This latest animal case of EEE confirms that even this late in the season, the risk for spread of EEE virus from infected mosquitoes is still present,” said Public Health Commissioner Robbie Goldstein.

“With more people going outside to enjoy the mild fall weather, we continue to recommend that residents take steps to protect themselves from mosquito bites until the first hard frost,” Goldstein added.

There have been 96 EEE-positive mosquito samples in Massachusetts this year.

Infected mosquitoes have been found in Barnstable, Bristol, Essex, Norfolk, Middlesex, Plymouth, and Worcester counties.

EEE is transmitted to humans through the bite of an infected mosquito. The last outbreak of EEE in Massachusetts occurred in 2019-2020, and resulted in 17 human cases with seven deaths, and nine animal cases.

There were no human or animal cases of EEE in Massachusetts in 2021, 2022, or 2023.

“Cooler temperatures will start to reduce mosquito activity, but people shouldn’t let their guard down yet,” said State Epidemiologist Catherine Brown. “We continue to strongly advise that everyone in areas at high and critical risk for EEE reschedule evening outdoor activities to avoid peak mosquito biting hours.”

DPH continues to urge people to use bug spray, and to wear long sleeves, long pants and socks when outdoors.