A Central Massachusetts resident hospitalized with Eastern equine encephalitis is the third person this season, and the first child, stricken with the mosquito-borne illness in the state, health officials said Monday.
The girl’s name and hometown were not disclosed to protect her identity. Based on the new case, state health officials raised the threat level for risk of further infections in several towns in Franklin and Worcester counties. The level has been raised to critical in Athol, Orange, and Royalston and to high in Erving, Petersham, Phillipston, Templeton, Warwick, Wendell, and Winchendon.
Communities designated as being at either critical or high risk for infection from the often-fatal virus, commonly known by the acronym EEE, are urged to cancel all planned evening outdoor events for the remainder of the season, until the first hard frost.
“EEE is an equal-opportunity virus, and it can strike anyone bitten by an infected mosquito,” said Kevin Cranston, director of the state Bureau of Infectious Disease. “Just because it’s after Labor Day doesn’t mean the threat of mosquito-borne illness has gone away.”
One of this year’s three confirmed human cases of EEE resulted in the death of a Worcester man in his 70s.
Health officials said they also have detected a third case of EEE in a horse, stabled in Rochester in Southeastern Massachusetts. That prompted them to raise the threat level to critical in Rochester and to high in the nearby communities of Acushnet, Freetown, Marion, and Wareham. They said that mosquito control projects will be increasing ground spraying activities in these communities.
The state blanketed swaths of Southeastern Massachusetts, typically a hotbed for the virus, twice this summer with pesticide from aerial spraying, and officials said that helped to tamp down the mosquito population.
But Cranston said there are no further plans to conduct aerial spraying this season because evening temperatures are dipping below 60 degrees and mosquitoes are less active in the cooler weather, making an aerial assault less effective.
“If it warms up, like it may later this week, people have every reason to maintain their guard,” Cranston said.
Disease trackers have historically focused surveillance for the virus in mosquitoes in the Southeastern part of the state, because it is home to the vast Hockomock Swamp, a prime breeding ground for the insects.
But mosquitoes infected with EEE and with West Nile virus, which typically produces less serious illness, started appearing much earlier this year than normal and in communities in Central and Western Massachausetts that only started monitoring for the viruses a couple years ago.
“All bets are off about where we might find isolated cases now because this is such an atypical year,” Cranston said.
There were two cases of EEE in August last year acquired in Massachusetts, a fatal case in a Bristol County man and an infection in a tourist from out of state.
Health officials urged residents to continue to take precautions to avoid mosquito bites, including using insect repellent, covering exposed skin when outside, and avoiding outdoor activities between dusk and dawn, when mosquitoes are most active.