Health

“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,” a public health official said.

By Carson Lyle

June 25, 2026 | 7:50 PM

2 minutes to read

Massachusetts mosquitoes tested positive for West Nile virus in a Clarksburg lab, making it the first case of the year, health officials said.

“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 Robbie Goldstein, MD, PhD.

While testing a June 16 batch of mosquitos for certain diseases, researchers discovered the insects contained the West Nile virus, the Massachusetts Department of Public Health said in a press release.

West Nile virus is transmitted to humans through the bite of infected mosquitos. In 2025, nine people contracted the virus, DPH said.

As of June 25, no human or animal has been diagnosed with the virus in the state, health officials said.

Anyone is susceptible to contracting West Nile virus, but those older than 50 have a higher risk for “severe disease,” the DPH said.

The majority of infected patients experience no symptoms. But those who are unlucky tend to experience fever and flu-like symptoms, the DPH said.

“With West Nile virus, it is difficult to predict the amount of activity we will see,” said State Epidemiologist Dr. Catherine M. Brown. 

Brown advises the public to consistently check mosquito-borne diseases webpages on mass.gov.

The DPH advises the public to apply insect repellent containing ingredients such as DEET, when outside.

DEET should not be used on infants under two months old and should be used in concentrations of 30 percent or less, health officials wrote.

The public should also mosquito proof their homes. Public health officials advise not having standing water nearby or in your home, as mosquitos lay their eggs in still water, the DPH said.

Animal owners should empty out buckets, tires, or wading pools, particularly when it rains, officials said.

“Horse owners should keep horses in indoor stalls at night to reduce their risk of exposure to mosquitoes,” health officials wrote.

Public officials also warned the public of Eastern Equine Encephalitis (EEE). No mosquitos carrying the virus have been detected as of Thursday, the DPH said.

Health officials advise horse owners  to use mosquito repellent on horses that are vet approved. 

“If an animal is suspected of having WNV or EEE, owners are required to report 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,” officials wrote.