West Nile virus has been detected in a mosquito sample collected in Clarksburg, located in Berkshire County, marking the first positive finding of the virus in Massachusetts this year, state public health officials announced Thursday. The sample was collected on June 16, according to the Massachusetts Department of Public Health.

West Nile virus is transmitted to humans through the bite of infected mosquitoes. Public health commissioner Robbie Goldstein emphasized the importance of protective measures, particularly as summer begins and mosquito activity typically increases. He advised residents to reduce standing water around their homes, wear clothing that limits exposed skin, repair window screens, and apply insect repellents containing EPA-registered ingredients.

“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,” Goldstein said.

In 2025, Massachusetts recorded nine human cases of West Nile virus. Symptoms can include fever and flu-like illness, though in rare cases, the disease can become more severe. The risk of serious illness is higher in individuals over the age of 50, according to the public health department.

State Epidemiologist Catherine M. Brown noted the unpredictability of virus activity from year to year and encouraged residents to stay informed by monitoring updates on mosquito-borne illnesses through the state’s official website.

Health officials also recommend that people remain indoors from dusk to dawn when mosquitoes are most active. Pet owners were advised to consult veterinarians regarding mosquito repellents for animals and vaccinations to protect against West Nile virus and Eastern Equine Encephalitis (EEE), another mosquito-borne illness present in the region.

These findings underscore ongoing efforts by public health authorities to track and mitigate mosquito-borne diseases as seasonal conditions favor the spread of these viruses.