MA Summer EEE Outbreak Wanes As Temperatures Cool In October

MASSACHUSETTS — The worst outbreak of Eastern equine encephalitis across Massachusetts in five years appears to be waning as the temperatures cool for the season.

The state Department of Public Health said on Wednesday afternoon that all cities and towns that had been listed as at "high" or "critical" risk for infection have been removed from those designations.

The change affects the cities and towns of Douglas, Dudley, Harvard, Northbridge, Oxford, Sutton, Uxbridge, Webster, Carver, Middleborough, Plymouth, Acton, Ayer, Boxborough, Concord and Littleton.

"Our surveillance data and past patterns of disease indicate that the risk from EEE is, thankfully, declining," said Public Health Commissioner Robbie Goldstein. "We know that most EEE infections occur by the end of September and this decision reflects that. Some risk from EEE will continue to exist until the first hard frost and we encourage people to continue to take steps to prevent mosquito bites as they enjoy the fall weather."

The state Department of Public Health said there were 96 EEE-positive mosquito samples, three horse cases and four confirmed human cases in Massachusetts this year. That is the most since 2019 when there were 17 human cases, seven deaths, and nine animal cases.

Officials said residents should still take precautions in wearing longer-sleeved clothing in wooded areas — which they may be doing anywhere because of the lower temperatures — and that mosquito activity this time of year is not always as centered around dawn and dusk as it is during most of the summer.

"The mosquitoes that are most likely to spread EEE to people are dying off and are present in much smaller numbers," State Epidemiologist Dr. Catherine Brown said. "In addition, their activity is driven more by temperature and humidity and somewhat less by the time of day."

Residents are still advised to use repellents when outdoors until the first hard frost of the fall in their area.

Repellents with an EPA-registered ingredient, such as DEET, permethrin, picaridin, or oil of
lemon eucalyptus are considered the most effective.

(Scott Souza is a Patch field editor covering Beverly, Danvers, Marblehead, Peabody, Salem and Swampscott. He can be reached at Scott.Souza@Patch.com. X/Twitter: @Scott_Souza.)