First West Nile Virus Sample Reported

BOSTON — The Mass. Department of Public Health (DPH) announced that West Nile virus (WNV) has been detected in mosquitoes in Massachusetts for the first time this year.

The Mass. State Public Health Laboratory today confirmed the presence of WNV in a mosquito sample that was collected on June 27 in the Town of Richmond in Berkshire County. No human or animal cases of WNV or Eastern Equine Encephalitis (EEE) have been detected so far this year. There is no elevated risk level or risk level change associated with this finding.

“The first WNV positive mosquito is often identified in Massachusetts during the last week in June,” said DPH Deputy State Epidemiologist Dr. Catherine Brown. “Risk for human infection generally builds through the season with peak risk occurring in August.’’

WNV is usually transmitted to humans through the bite of an infected mosquito. In 2016, there were 16 human cases of WNV infection acquired in Massachusetts. While WNV can infect people of all ages, people over the age of 50 are at higher risk for severe disease. 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.

People have an important role to play in protecting themselves and their loved ones from illnesses caused by mosquitoes, Brown said. The tools for prevention include using a mosquito repellent with an EPA-registered ingredient according to the directions on the label, wearing clothing to reduce exposed skin when weather permits, draining standing water to prevent mosquito breeding and repairing window screens to keep mosquitoes out of your home, she said.