Deadly mosquito-borne virus prompts Massachusetts cities to close parks and fields

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In several counties in eastern Massachusetts, local parks and fields have been closed following an outbreak of a rare and potentially deadly mosquito-borne virus.

The Massachusetts State Department of Public Health (DPH) announced Saturday that aerial and truck-borne mosquito control measures will be deployed following an outbreak of the Eastern Equine Encephalitis (EEE) virus.

According to the department, the virus is a “rare but serious and potentially fatal disease” that can affect people of all ages. On Aug. 16, a Worcester County man in his 80s became the first human case recorded this year.

EEE is generally transmitted to humans through the bite of an infected mosquito. Symptoms may include fever, headache, vomiting, diarrhea, seizures, behavioral changes and drowsiness, according to the Center for Disease Control and Prevention (CDC).

About 30 percent of people with eastern equine encephalitis die, and many survivors have persistent neurological problems. There is no vaccine or treatment for EEE.

The first EEE-positive mosquitoes of the season in Massachusetts were reported in Carver on July 3, but other mosquitoes have previously been identified in several other counties.

The DPH said that mosquito spraying would be carried out by truck in Plymouth County and parts of Worcester County. As of Saturday, 10 communities in Massachusetts were raised to high or critical risk for EEE, the department said.

The eight communities in the spray area are Carver, Halifax, Kingston, Middleborough, Plymouth, Plympton, Rochester and Wareham.

The five communities in the truck spray zone are Douglas, Dudley, Oxford, Sutton and Uxbridge. Spraying is expected to take place over the course of next week and will take place at night.

“We haven’t seen an outbreak of EEE in Massachusetts in four years,” said DPH Commissioner Robbie Goldstein.

“This year’s outbreak and activity increases the risk to communities in parts of the state. We must use all of our available tools to reduce the risk and protect our communities. We ask everyone to do their part.”

During the last EEE outbreak in Massachusetts in 2019-2020, there were 17 human cases and seven deaths.

“Due to the increased risk of EEE and the first human case of the season, the state is taking decisive action to protect public health,” said MDAR Commissioner Ashley Randle. “Aerial spraying will target mosquitoes carrying the EEE virus.

“While these measures are critical to reducing the risk of transmission, it is vital that everyone remains vigilant and follows personal protective guidelines to protect our community.”

The pesticide used is Anvil 10+10, which has been extensively tested and is used in the US for both ground and aerial application to control mosquitoes. It is approved by the Environmental Protection Agency (EPA).

Residents of the affected areas have also been advised to prevent mosquito bites by using mosquito repellents, being aware of peak mosquito hours, mosquito-proofing their homes and protecting their animals.