2 More Cases Of Serious Mosquito-Borne Viruses Confirmed In MA

MASSACHUSETTS — State health officials announced Thursday that an additional human case of human case of Eastern equine encephalitis and one additional human case of West Nile virus were confirmed in Massachusetts.

Both cases are in men in their 70s, officials said. One man was exposed to EEE in central Middlesex County, bringing the total number of EEE cases in Massachusetts this year to three. The other man was exposed to WNV in southern Middlesex County, marking seven cases of WNV in Massachusetts this year.

Southern Middlesex County was already marked as high risk for WNV. With the new case, WNV risk levels in Stoneham and Wakefield in Middlesex County have been raised to high.

EEE risk levels in Acton, Ayer, Boxborough, Carlisle, and Littleton in Middlesex County and Harvard in Worcester County have been raised to high. The EEE risk levels in Bedford, Billerica, Chelmsford, Concord, Framingham, Groton, Lincoln, Shirley, Stow, Tyngsborough, Wayland, and Westford in Middlesex County — and Berlin, Bolton, Clinton, and Lancaster in Worcester County — have been raised to moderate.

See Also:

• Peabody To Spray For Mosquitoes At Parks, Fields After EEE Detected
• EEE Detected In Cape Cod Mosquitoes
• 2 Mosquito Samples Test Positive For West Nile Virus In Worcester

"Today’s announcement of additional West Nile virus and Eastern equine encephalitis cases makes it clear that mosquito season is not over," Public Health Commissioner Robbie Goldstein, MD, PhD. said Thursday. "It is essential that residents continue to use mosquito repellent with an EPA-registered active ingredient every time they are outdoors. We also strongly recommend that residents and towns in areas at high risk for EEE reschedule their evening outdoor events to avoid peak mosquito biting hours."

There have been 88 EEE-positive mosquito samples in Massachusetts this year, with most activity focused in Plymouth and Worcester counties, according to officials. However, infected mosquitoes have also been found in Bristol, Essex, and Middlesex counties.

There have been 299 WNV-positive mosquito samples so far this year detected from Barnstable, Berkshire, Bristol, Dukes, Essex, Franklin, Hampden, Middlesex, Norfolk, Plymouth, Suffolk, and Worcester counties, officials said.

EEE and WNV are transmitted to humans through the bite of an infected mosquito. The last outbreak of EEE occurred in 2019-2020 and resulted in 17 human cases with seven deaths.

There were six human cases of WNV and no animal cases in 2023. No animal cases of WNV have been detected so far this year.

"Mosquito behavior starts to change in September," State Epidemiologist Dr. Catherine Brown said.
"They will be less active during cooler temperatures. However, during periods of warmer weather, such as are being forecast for the end of next week, mosquitoes will be out and looking for their next meal."

To help protect yourself and your family from mosquito-borne illness, apply insect repellent when going outdoors, wear long sleeves or other protective clothing when outdoors, minimize outdoor activity between dusk and dawn, and avoid leaving standing water in containers such as buckets, tires, and wading pools, according to health officials.