The state has finished spraying parts of Middlesex and Worcester counties—which include large swathes of the Boston area, including Cambridge and Newton—to combat the spread of mosquito-borne Eastern Equine Encephalitis, a debilitating, sometimes fatal virus that impacts the nervous system.
At least one Massachusetts resident has died from the virus this year—a woman in Bristol County—and there have been four reported cases. Mosquitos pick up EEE from birds and spread it through bites. Humans cannot spread the disease once infected.
Despite the high-profile spread this summer, the risk of contracting EEE is still low in a sizable portion of Massachusetts, including most of the Boston area, according to the state Department of Public Health, which has been tracking the spread through maps and updates.
The highest-risk areas are in the south-central portion of the state and between the Boston area and the Cape. See below for the latest Mass. Public Health Department risk map.
Still, even in those low-risk areas, residents should take certain precautions, including wearing mosquito repellent and long sleeves while outdoors. EEE moves quickly through the central nervous system, with symptoms such as headaches and fever striking three to 10 days after the mosquito bite. There is no treatment for EEE, and few recover completely.
Massachusetts has had a long history with EEE. The virus was first documented here in 1938, and there are outbreaks every 10 to 20 years, with such spreads lasting two to three years. The last outbreak was from 2010 to 2012, with nine confirmed cases and four fatalities, according to the state Bureau of Infectious Disease and Laboratory Sciences.