BOSTON (WWLP) – The Massachusetts Department of Public Health (DPH) has announced the detection of the third human case of West Nile virus (WNV) in the state this year.

A man in his 50s was exposed in Hampden County. The additional two individuals are a woman in her 70s who contracted the virus outside the state, and a man in his 40s who was exposed to the virus in Middlesex County, an area previously identified as having a moderate risk.

Health officials are urging residents to exercise caution and take preventive measures to avoid mosquito bites. The risk of WNV infection is currently deemed moderate in the Greater Boston area (Middlesex, Norfolk, and Suffolk counties), as well as in parts of Berkshire, Bristol, Hampden, Hampshire, Plymouth, and Worcester counties.

“This is the third person with West Nile virus infection identified in Massachusetts this year,” said Public Health Commissioner Robert Goldstein, MD, PhD. “It continues to be important for people to take steps to prevent mosquito bites, including by using a mosquito repellent with an EPA-registered active ingredient, draining standing water around their homes, and repairing window screens. Risk from mosquito-borne disease will continue until the first hard frost.”

Last year, Massachusetts recorded eight human cases of WNV infection. The virus is primarily transmitted to humans through mosquito bites. Although people of all age groups can be infected, individuals over the age of 50 are at a higher risk of developing severe symptoms. The majority of WNV-infected individuals exhibit no symptoms, while those who do experience symptoms often suffer from fever and flu-like illness. Severe cases are rare but can occur.

Tips to avoid mosquito bites:

• When outdoors, wear long pants, a long-sleeved shirt, and socks.
• Use a repellent with DEET according to the instructions on the product label.
• Keep mosquitoes out of your house by repairing holes in screens and making sure screens fit tightly to doors and windows.
• Schedule outdoor events to avoid the hours between dusk and dawn when mosquitoes are most active.
• Remove areas of standing water around your home twice a week to eliminate sources of mosquito breeding.

West Nile virus (WNV) first appeared in the United States in 1999. Since the initial outbreak in New York City, the virus has spread across the U.S. and was identified in birds and mosquitoes in Massachusetts during the summer of 2000.