Health Officials Announce Season’s First EEE-Positive Mosquito Samples
The Massachusetts Department of Public Health (DPH) today announced that Eastern equine encephalitis (EEE) virus has been detected in mosquitoes in Massachusetts for the first time this year. The presence of EEE was confirmed in mosquito samples collected on August 17 in the town of Kingston in Plymouth County. No human or animal cases of EEE have been detected so far this year.
Today’s finding increases the risk level of EEE to moderate in the communities of Carver, Halifax, Kingston, and Plympton.
“The last EEE outbreak in Massachusetts occurred in 2024 and, since then, there have been no human cases of EEE reported in the state,” said Public Health Commissioner Robbie Goldstein, MD, PhD. “Today’s finding alerts us to the presence of EEE in Massachusetts this year. While this is late in the season for the first detection of EEE in mosquitoes, when combined with all the evidence of West Nile virus in mosquitoes in Massachusetts, we are asking everyone in Massachusetts to take the necessary precautions to prevent mosquito bites. The Department of Public Health recommends that people use mosquito repellent when they are spending time outdoors so they can enjoy the rest of the summer and decrease their risk of being bitten.”
EEE is a rare but serious and potentially fatal disease that can affect people of all ages. EEE is generally spread to humans through the bite of an infected mosquito. There were 12 human cases of EEE in Massachusetts in 2019 with six deaths; in 2020, there were five human cases and one death. In 2024, there were four human cases with one death. There were no human cases of EEE in Massachusetts in 2021, 2022, 2023, or 2025.
“EEE activity in Massachusetts tends to occur in outbreak cycles,” said State Epidemiologist Dr. Catherine M. Brown. “When EEE is found in mosquitoes later in the season like this, there is less opportunity for the risk to increase to very high levels. But anytime EEE virus is in mosquitoes, it can be spread to people. We rely on our mosquito surveillance program to monitor for the presence of virus to let people know when and where the risk is occurring so they can take steps to protect themselves.”