10 Massachusetts communities at high risk of mosquito-spread virus 'Triple E'

The threat of Eastern Equine Encephalitis virus has prompted several Massachusetts towns to implement targeted mosquito spraying to protect residents.

According to the Centers for Disease Control and Prevention, this virus, often called Triple E, is transmitted through the bite of an infected mosquito and can cause a "rare but severe illness." Although the number of annual cases is low, the virus can pose a significant health risk.

The CDC says most people infected don’t have any symptoms, but symptoms can range from a febrile illness to more severe neurological problems.

The disease is particularly dangerous if it leads to encephalitis, or inflammation in the brain, with approximately 30% of people with encephalitis dying.

Many survivors experience long-term neurological issues, according to the CDC, which notes there are no human vaccines or specific treatments available, making prevention crucial.

Earlier this month, Massachusetts officials reported the season's first human case of Triple E, marking the first occurrence in the state since 2020.

There have been three reported human cases of Triple E this year in three states: Massachusetts, New Jersey and Vermont.

Historically, 2019 saw the highest number of human Triple E cases with 38 reported, according to the CDC.

Currently, 10 communities in Massachusetts are under high or critical risk of the virus, according to the state's Department of Public Health .

High-risk communities include Plymouth, Carver, Middleborough, Dudley, Uxbridge and Northbridge.

Critical-risk communities include Webster, Oxford, Sutton and Douglas.

In response, aerial spraying will be conducted in parts of Plymouth County, while truck-mounted spraying will target areas in Worcester County. The goal by health officials is to mitigate mosquito populations that are the primary spreaders of the virus.

The pesticide used is Anvil 10+10, an Environmental Protection Agency-registered product "extensively tested and used in both ground-level and aerial spraying in the U.S. to control mosquitoes," according to the Massachusets DPH.

The agency reports that compounds in Anvil 10+10 have proven to be "highly effective in killing mosquitoes" globally for two over two decades.

"Due to the increased EEE risk and the first human case of the season, the state is taking decisive action to protect public health," Ashley Randle, Massachusetts Department of Agricultural Resources commissioner, said in a press release Saturday.

"Aerial spraying will target mosquitoes carrying the EEE virus. While these measures are crucial for reducing transmission risk, it's vital for everyone to stay vigilant and follow personal protection guidelines to safeguard our community," Randle said.

Additionally, officials in Plymouth County announced that as of Friday, Aug. 23, public parks and fields will be closed from dusk to dawn due to the high-risk status of EEE.

The CDC advises individuals to minimize mosquito exposure by using insect repellent, wearing long sleeves and pants and avoiding outdoor activities during peak mosquito activity times.

Dr. Jade A Cobern, M.D., MPH, a licensed and practicing physician board-certified in pediatrics and preventive medicine, is a medical fellow on the ABC News Medical Unit.