Massachusetts Reports First West Nile Virus-Positive Mosquitoes of 2026 Season
BOSTON — Massachusetts public health officials have confirmed the state’s first mosquito sample to test positive for West Nile virus (WNV) this year, prompting renewed reminders for residents to take precautions against mosquito bites as summer begins.
The Massachusetts Department of Public Health (DPH) said the infected mosquito sample was collected June 16 in Clarksburg, Berkshire County, and confirmed by the Massachusetts State Public Health Laboratory.
“With warmer weather and summer officially beginning this week, it is the time of year when we typically begin detecting West Nile virus in mosquito populations,” said Public Health Commissioner Dr. Robbie Goldstein. “These findings serve as an important reminder that people should take steps to protect themselves from mosquito bites.”
No human or animal cases of West Nile virus have been reported in Massachusetts so far this year. In 2025, the state recorded nine human cases of the virus. Officials also said no evidence of Eastern Equine Encephalitis (EEE) has been detected this season.
State Epidemiologist Dr. Catherine M. Brown said residents should monitor mosquito activity updates throughout the summer.
“With West Nile virus, it is difficult to predict the amount of activity we will see,” Brown said. “We encourage everyone to make it a habit to check the mosquito-borne diseases webpages on Mass.gov so you know when and where WNV activity is occurring in the state.”
Health officials recommend using EPA-registered insect repellents, wearing long sleeves and pants when outdoors, especially from dusk to dawn, eliminating standing water around homes, and repairing window and door screens to reduce mosquito exposure.
People over age 50 are considered at greater risk of developing severe illness from West Nile virus, although most infected individuals experience no symptoms or only mild flu-like illness.
