KINGSTON, MA — The first mosquitoes with confirmed positive tests for Eastern equine encephalitis were found on the South Shore this week.
The state Department of Public Health said that the presence of EEE was found in a mosquito sample from Kingston collected on Aug. 17.
No human or animal cases of EEE have been detected so far this year.
The finding resulted in an increase of EEE risk level to moderate in Carver, Halifax, Kingston and Plympton.
"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," Public Health Commissioner Robbie Goldstein said. "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 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 the virus to let people know when and where the risk is occurring so they can take steps to protect themselves."
Residents are advised to use an insect repellent when outdoors, beware of peak mosquito hours at dusk and dawn and to reconsider outdoor activities in the evening and morning.
Wearing long sleeves, long pants, and socks when outdoors will help keep mosquitoes away from your skin.
Mosquitoes lay their eggs in standing water. Limiting the number of places around a home for mosquitoes to breed can be done by either draining or discarding items that hold water.
Check rain gutters and drains. Empty any unused flowerpots and wading pools and change the water in birdbaths frequently.
Keep mosquitoes outside by having tightly fitting screens on all your windows and doors.
Horse owners should keep horses in indoor stalls at night to reduce their risk of exposure to mosquitoes. Owners should also speak with their veterinarian about mosquito repellents approved for use in animals.
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