Two more human cases of West Nile virus were detected in Massachusetts, days after the first human case in the state was detected in 2025.
A man in his 40s who was likely exposed in Hampden County and a man in his 80s exposed in Middlesex County make up the latest cases, the Massachusetts Department of Public Health (DPH) said in a statement on Friday.
“Given how many mosquitoes have been found carrying West Nile virus this summer, we expected that there would be human infections this year,” Public Health Commissioner Robbie Goldstein said in the statement. “Infections can continue to occur until the first hard frost of the season, which is likely still many weeks away. We are encouraging everyone to continue to take the necessary steps to protect themselves from mosquito bites, including by using mosquito repellent, wearing long sleeves and pants to reduce exposed skin, and to drain anything that may be collecting water outside your home.”
The new cases have raised the risk level to high in Ashland, Framingham, Marlborough, Natick, Sherborn, Southborough, Sudbury, and Wayland.
On Tuesday, DPH stated that a woman in her 70s was diagnosed while in Middlesex County.
With these first human cases of the year now catalogued, DPH will update the public on West Nile virus cases in Massachusetts with weekly press releases each Friday should any new cases be confirmed.
“DPH encourages everyone to use this online resource regularly to stay up to date on risk levels in their community and around the state,” the department stated.
DPH first detected West Nile virus in mosquito samples on June 17 and, since then, 376 mosquito samples across several counties have tested positive. The risk is now high across 28 communities in Suffolk, Middlesex, Essex, and Worcester counties. Elsewhere, 175 towns and cities in Barnstable, Berkshire, Bristol, Essex, Franklin, Hampden, Hampshire, Middlesex, Norfolk, Plymouth, Suffolk, and Worcester counties are at a moderate risk.
The first case of West Nile virus detected in Massachusetts this year was in a goat in Lunenburg in July.
The department suggests that people use insect repellent when outside. The repellent should be made with an EPA-registered ingredient such as DEET, permethrin, picaridin, or oil from lemon eucalyptus.
DEET products should not be used on babies younger than two months old and should be used in concentrations of 30% or less on older kids. Oil of lemon eucalyptus shouldn’t be used on kids under three.
The department also suggested that people reschedule any outdoor activities during peak mosquito-biting times — dusk to dawn.
People should also wear long-sleeved clothes to prevent mosquito bites. They should also remove standing water from their homes and install window screens to keep mosquitoes out of their homes.
