State health officials say a routine mosquito test in Clarksburg, up in Berkshire County, has turned up West Nile virus, marking the first detection in Massachusetts this season and giving residents a fresh reason to reach for the bug spray. The positive result came from a mid-June mosquito batch, and as of Thursday there were no reported human or animal infections. Even so, authorities are urging people across the Berkshires to step up their mosquito-bite precautions as summer conditions fuel heavier mosquito activity.
According to reporting by mosquitoes in Clarksburg provide season's first sample, the Department of Public Health identified West Nile virus in a mosquito sample collected on June 16, after the state public health laboratory ran confirmatory testing. The paper noted that its account was based on a State House News Service dispatch that went out to local outlets.
Boston.com relayed the Department of Public Health press release that highlighted the Clarksburg finding and reported that in 2025, nine people contracted West Nile virus in Massachusetts. The outlet quoted State Epidemiologist Dr. Catherine Brown, who said it is difficult to predict how intense this year’s season will be and urged residents to consistently use repellents and window screens.
What officials found
West Nile virus is spread to people through the bite of infected mosquitoes. Most infected individuals never develop symptoms, while a smaller share experience fever and flu-like illness. According to guidance from the CDC, severe neuroinvasive disease is less common but is more likely in older adults and people with weakened immune systems.
How to protect yourself
Health officials recommend using EPA-registered insect repellent, wearing long sleeves and long pants during peak mosquito hours at dawn and dusk, and removing standing water where mosquitoes can breed. The Department of Public Health posts local risk maps and safety tips on its Massachusetts Arbovirus Update page, which is aimed at both residents and horse owners.
Local mosquito control and the bigger picture
The Berkshire County Mosquito Control Project has previously recorded West Nile virus in the county, and its 2024 annual report lists multiple positive mosquito samples, including ones from Clarksburg. Local trapping and testing are part of routine surveillance that helps boards of health and the state set community risk levels. Details are outlined in the Berkshire County Mosquito Control Project report.
For ongoing updates and local risk maps, residents are urged to monitor the state’s arbovirus surveillance resources and follow local health advisories. If you suspect a sick animal or find multiple dead birds, officials say to report it to the Department of Agricultural Resources or the Department of Public Health, using the contact information provided in the DPH release covered by Boston.com.
