As residents enjoy the unofficial end to summer this Labor Day weekend, the Massachusetts Department of Public Health on Friday announced that the eastern equine encephalitis virus, known as EEE, has been detected for the first time this year in the state in neighboring Worcester County, prompting a warning to use mosquito repellent.

The presence of EEE was confirmed Friday by the Massachusetts State Public Health Laboratory in mosquito samples collected on Aug. 30 in Douglas and Southbridge. This discovery increases the risk level of EEE to moderate in the Worcester County communities of Douglas, Dudley, Southbridge, Sturbridge, Uxbridge and Webster.

EEE is a rare but serious and potentially fatal disease that can affect people of all ages, and it is usually spread to humans by the bite of an infected mosquito. This is the first time in two years that risk of EEE exposure has been raised as a concern in the state, according to Public Health Commissioner Robert Goldstein.

“After the EEE outbreak cycle that occurred in 2019 and 2020, there was no EEE activity in Massachusetts in 2020 and 2021,” he said in a statement. “This is a late-season emergence for EEE, which should keep the risk level from rising too much or too quickly. However, some risk for mosquito-borne disease will continue until the first hard frost, and people should take steps to prevent mosquito bites.”

According to Mass DPH, there were 12 human cases of EEE in Massachusettsin 2019, which resulted in six deaths. In 2020, there were five human cases and one death from EEE.

“Transmission of EEE to a person late in the season can happen,” noted state epidemiologist Dr. Catherine M. Brown. “Mosquitoes will be more active during warm and humid weather as we are forecast to have this weekend. I encourage everyone to use mosquito repellent when they are outdoors enjoying the last unofficial weekend of summer.”

To avoid mosquito bites, MassDPH recommended the following strategies:

• Use an insect repellent with DEET (diethyltoluamide), an EPA-registered ingredient. Insect repellents also may contain permethrin, picaridin or oil of lemon eucalyptus. Insect repellent should be applied according to the directions on the product label. DEET products should not be used on infants under 2 months of age and should be used in concentrations of 30% or less in older children. Oil of lemon eucalyptus should not be used in children under 3 years old.
• Reschedule outdoor activities so that they do not occur during the peak mosquito time between dusk and dawn.
• Wear long sleeves and long pants when outdoors to keep mosquitoes away from the skin.

To mosquito-proof a home and protect pets, standing water should be eliminated from containers such as buckets, tires, wading pools and troughs where mosquitoes can breed. Horses should be kept inside indoor stalls at night to prevent exposure. If an animal is suspected of having either EEE or West Nile virus, owners are required to report it to the Department of Agricultural Resources, Division of Animal Health, by calling 617-626-1795, as well as to MassDPH by calling 617-983-6800.

For more information and positive results for EEE and WNV, go to this link or call the state’s Department of Epidemiology 617-626-6800. Information is updated on a daily basis.