Human-biting mosquitoes infected with Eastern equine encephalitis have been detected in Reading, the first time this season that EEE-
carrying insects that can spread the often-fatal disease to people have been found outside Cape Cod and Southeastern Massachusetts, which is traditionally a hotbed of the virus.
“This is very unusual to have EEE in Reading, let alone in mosquitoes that bite mammals,” said Ruth Clay, the town’s health director.
Catherine Brown, the state’s public health veterinarian, said the unlikely finding in Reading illustrates the potential for human-biting mosquitoes with the virus to pop up in other areas of the state not typically thought of as breeding grounds for the EEE virus.
“I don’t think we can predict what will happen,” she said.
Mosquitoes infected with EEE have been found in other parts of the state as well this summer — including Westborough, Pittsfield, and Topsfield — but they were not the type that typically bites humans.
Disease trackers pinpointed mosquitoes with Eastern equine encephalitis virus in Massachusetts weeks earlier than usual this season, and health officials said the early arrival was probably spurred by the warm winter.
Brown encouraged residents to take precautions to avoid being bitten: Use insect repellent, cover exposed skin when outside, and avoid outdoor activities between the hours of dusk and dawn, when mosquitoes are at their most active.
In Reading, officials plan to use trucks to spray pesticide from dusk until about 11:30 p.m. Monday and Tuesday evenings, weather permitting.
The infected batch of Reading mosquitoes was found along a residential street that abuts wetlands near the Lynnfield line, said David Henley, superintendent of the East Middlesex Mosquito Control Project.
Henley, who has led the project since 1982, said this is the first time he can remember human-biting mosquitoes with the EEE virus in his district, which extends from Framingham to Everett.
The town has not canceled outdoor evening activities because the risk of infection from mosquito bites is still considered moderate, Clay said. State health officials recommend cancellation when the risk level rises above moderate, which is largely determined by the number of infected human-biting mosquitoes that are found.
In Southeastern Massachusetts, where aerial pesticide spraying blanketed 21 communities last month after numerous batches of infected mosquitoes were detected, six of the cities and towns will be sprayed again Monday night, state health officials said Friday.
The July spraying reduced the mosquito populations by 60 percent in the areas covered, health officials said, but large numbers of the infected insects are still found in the region.
Bridgewater, Easton, Norton, Raynham, Taunton, and West Bridgewater will be sprayed between 7:45 p.m. Monday and 2:30 a.m. Tuesday, officials said.
Aerial spraying is heavily dependent on weather conditions, and spraying can be postponed up to the last minute, so residents are urged to check the Department of Public Health website for the latest updates.
Aerial spraying of pesticides reduces, but does not eliminate the risk of mosquito-borne illness, health officials said. All residents, whether inside or outside the spray zone, are urged to continue taking personal precautions to avoid mosquito bites.Kay Lazar can be reached at firstname.lastname@example.org. Follow her on Twitter @GlobeKayLazar.