EEE has been detected in mosquitoes in the Bay State for the first time this year, as the risk level for EEE was raised in communities ahead of Labor Day weekend.
After zero EEE activity in Massachusetts over the last two years, the state Department of Public Health announced the season’s first Eastern equine encephalitis positive mosquito samples.
The presence of EEE was confirmed on Friday by the Massachusetts State Public Health Laboratory in mosquito samples collected in Douglas and Southbridge in Worcester County. No human or animal cases of the rare but serious and potentially fatal disease have been detected so far this year.
This EEE detection comes after the Department of Public Health earlier this week reported the first two human cases of West Nile virus in state residents this year. A man in his 40s was exposed to the virus in Middlesex County, which is an area already known to be at moderate risk for West Nile virus. The other case is a woman in her 70s, who was exposed to the virus in another part of the country.
After the EEE positive mosquito samples, the risk level of EEE has been raised to moderate in Douglas, Dudley, Southbridge, Sturbridge, Uxbridge, and Webster in Worcester County.
“After the EEE outbreak cycle that occurred in 2019 and 2020, there was no EEE activity in Massachusetts in 2021 or 2022,” said Public Health Commissioner Robert Goldstein.
“This is a late season emergence for EEE which should keep the risk level from rising too much or too quickly,” Goldstein added. “However, some risk from mosquito-borne disease will continue until the first hard frost and people should take steps to prevent mosquito bites.”
EEE is generally spread to humans through the bite of an infected mosquito. There were 12 human cases of EEE in Massachusetts in 2019 with six deaths, and five human cases with one death in 2020.
There were no human cases of EEE in Massachusetts in 2021 or 2022.
“Transmission of EEE to a person late in the season can happen,” said State Epidemiologist Catherine M. Brown. “Mosquitoes will be more active during warm and humid weather as we are forecast to have this weekend.”
Brown added, “I encourage everyone to use mosquito repellent when they are outdoors enjoying the last unofficial weekend of summer; you can also use clothing to cover exposed skin and if you notice that you are getting bitten, you should consider moving indoors.”