State Public Health Officials Announce First EEE-Positive Mosquito Sample in 2025

On July 23, the Massachusetts Department of Public Health (DPH) 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 a mosquito sample collected on July 21 in the town of Belchertown in Hampshire County.

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. In Massachusetts, the virus is most often identified in mosquitoes found in and around freshwater, hardwood swamps. 

No human or animal cases of EEE have been detected in Massachusetts so far this year. In Cambridge, the EEE risk is remote, meaning that EEE is not usually found in our area. You can view the risk map on the state’s website. 

Public health officials urge residents to take steps to avoid mosquito bites, mosquito-proof your home, and protect your animals. 

Avoid Mosquito Bites

• Apply mosquito repellent.
• Be aware of peak mosquito hours (dusk to dawn).  
• Wear long sleeves, long pants, and socks when outdoors to keep mosquitoes away from your skin.

Mosquito-Proof Your Home

• Drain standing water. Mosquitoes lay their eggs in standing water. This includes checking rain gutters and drains.
• Install or repair screens to mosquito proof your house. 

Protect Your Animals

• Drain standing water from containers. Water troughs provide excellent mosquito breeding habitats and should be flushed out at least once a week during the summer months to reduce mosquitoes near paddock areas.
• Keep horses in indoor stalls at night to reduce their risk of exposure to mosquitoes.
• Speak with your veterinarian about mosquito repellents approved for use in animals and vaccinations to prevent West Nile virus and EEE.
• Report any animal suspected of having WNV or EEE to the Department of Agricultural Resources, Division of Animal Health by calling 617-626-1795, and to the Department of Public Health by calling 617-983-6800.

More information about mosquito-borne illnesses can be found on the health department’s website and DPH’s website.