The Massachusetts Department of Public Health (DPH) today announced the third human case of West Nile virus (WNV) in the state this year. The woman is a resident of Middlesex County in her 20’s. She was never hospitalized. There is no risk level change associated with this finding.


“When overnight temperatures are cool, mosquitoes are more active around dusk and into the early evening. They may also be active during warmer, humid days in areas without direct sunlight,” said DPH State Public Health Veterinarian Dr. Catherine Brown. “People need to continue to use insect repellant, cover up exposed skin, and reduce outdoors during those times when mosquitoes are at their most active. The risk of mosquito-borne illness will continue until the first hard frost.”

This is the third human case of WNV in the state this year. In 2013, there were eight human cases of WNV infection identified in Massachusetts. While WNV can infect people of all ages, people over the age of 50 are at higher risk for severe disease. WNV is usually transmitted to humans through the bite of an infected mosquito. Most people infected with WNV will have no symptoms. When present, WNV symptoms tend to include fever and flu-like illness. In rare cases, more severe illness can occur.

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According to the Centers for Disease Control and Prevention (CDC), as of September 16, a total of 45 states and the District of Columbia have reported West Nile virus infections in people, birds, or mosquitoes. Overall, 725 cases of West Nile virus disease in people have been reported to CDC, including 25 fatalities.