LEVERETT – In July 2020 Gov. Charlie Baker signed into law the Act to Mitigate Arbovirus in the Commonwealth that authorized broad aerial spraying to control eastern equine encephalitis (EEE) and West Nile virus (WNV). That sent communities scrambling to opt out of the program that, critics say, may do more harm than good.

Opting out requires a town to have an alternative plan acceptable to the state’s Deptartment of Public Health (DPH). That’s no small task for municipalities with limited resources. Leverett was already working with a group from the University of Massachusetts (UMass) Amherst in an investigation of the local tick population. Now the same group will help gather and analyze local mosquitos.

“Melissa [Colbert, a member of the Select Board] started working on that project with UMass,” said Town Administrator Margie McGinnis. “We ended up being a pilot program for them to see about testing mosquitos and doing a mosquito collection project in-house.”

Residents volunteered to collect samples at five sites across the town and secured females from seven different species of mosquitos. Those samples are now at UMass for testing, where it will be determined whether they carried the viruses that cause EEE and WNV.

According to sources on Mass.gov, the commonwealth’s official website, EEE and WNV are dangerous, but uncommon. In 2022 there were 95 positive tests of mosquitos for WNV and zero for EEE across the state. WNV resulted in eight cases of encephalitis — swelling of the brain — or swelling that also involves the surrounding membranes. Either condition may lead to death.

Between 2011 and 2020, 148 people were reported with WNV infection in Massachusetts. Seven died. State information also presents that outbreaks are cyclical, and that a cycle of disease, typically lasting two to three years, may have begun in 2019.

Aerial spraying is carried out at night, when people and pets are most likely to be indoors and unaffected. The website recommends changing the water in pet dishes in the morning. The pesticide used, Anvil 10+10, breaks down within a day and poses no health threat to humans or animals.

Those claims by the state did not allay the concerns of residents, who authorized spending to come up with an alternate plan at Town Meeting in spring of 2022.

“The town appropriated $5,000 … and that was what allowed us to fund it,” McGinnis said. A homegrown plan for mosquito control “would allow us to opt out, and for the state to approve our opt-out plan.”
Residents may have concerns because there is disagreement whether aerial spraying accomplishes any reduction in disease-carrying mosquitos. The pesticide sprayed from planes may also not be safe for humans, animals and amphibians.

“Aerial spraying is faith-based disease prevention…without scientific support,” said Kyla Bennett, Science Policy Director for Public Employees for Environmental Responsibility (PEER) in a complaint against the new spray program. “Spraying only targets flying adults, not the eggs, larva or pupae, meaning that many repeat applications are needed to have any hope of controlling emerging adult mosquitoes.”

According to a press release from Bennett’s office, the DPH made an assessment and acknowledged it is not possible to measure the reduction of EEE cases due to aerial spraying. The PEER document also quotes DPH sources admitting that “reduction of risk from EEE relies primarily on the use of personal prevention behaviors by individuals.”

Measures individuals may use include staying indoors at peak mosquito times, using bug spray and wearing appropriate clothing.

Anvil 10+10, already sprayed across the landscape in many towns in eastern counties where EEE is more prevalent, has a questionable safety profile. The Deptartment of Marine Fisheries considers the pesticide highly toxic to fish and aquatic invertebrates. The Department of Environmental Protection also considers the product highly to very highly toxic to fish, aquatic invertebrates and honeybees.

Bennett suggested the pesticide, if inhaled by residents, will have health impacts.

“In addition to all the other harmful side effects, spraying carcinogenic immune suppressors over a wide area is not a very smart thing to do during a pandemic,” Bennett said.

Under the new spray plan towns are required to join a mosquito control district. A comprehensive alternative plan for controlling viral carriers would allow them to forgo that requirement, though an alternative plan will take time and technical expertise to draft. The town hopes to have a plan drawn up with the assistance of students and the experts at UMass Amherst.

“The whole point of this was…so that we could opt out,” McGinnis said.

Opting out of the new spray plan will require a vote at Town Meeting in April.