Middleborough has become the first town in Southeastern Massachusetts to be designated a “critical” risk for Eastern equine encephalitis after a horse in the rural Plymouth County community died last week of the mosquito-borne disease.
State health officials also raised the risk to “high” in neighboring Plympton, urging it and all similarly designated area communities to cancel outdoor evening activities for the rest of the mosquito season.
That is generally considered to last until the first killing frost, which is not expected until sometime in October. Complicating the situation, state and local officials said, is the weather; spraying has ended for the season because the cool night air renders the insecticides ineffective.
As soon as the town’s risk level was raised, Jeanne Spalding, Middleborough’s health officer, ordered that all outside activities must end before the peak mosquito feeding hours of dusk to dawn. Residents also are being urged to avoid contact with mosquitoes at any time of the day.
However, Spalding said she has considered the situation dire since the first pools of West Nile- and EEE-infected mosquitoes were detected in the area this summer. Elsewhere in the state, only Belchertown and Tyngsborough are classified as having critical risk. Towns near Middleborough at moderate risk for infected mosquitoes will remain at that level.
So far this year, there have been three human cases of West Nile virus and one human case of EEE, said Catherine Brown, the state Department of Public Health’s veterinarian.
The Middleborough case is the fourth instance of EEE in a horse, Brown said. Another case of West Nile virus was recently detected in a horse in Dartmouth, she said.
That community remains at moderate risk, she said.
Michele Morgan Bolton can be reached at michelebolton@live.