Experts say best protection against EEE in Massachusetts is personal precaution

Photo Courtesy: Wikimedia Commons

After years of only a few cases and a handful of positive mosquito samples, Eastern Equine Encephalitis, or “Triple E,” is back in Massachusetts with a bite.

Lindsey Vickers
BU News Service

BOSTON – After years of only a few cases and a handful of positive mosquito samples, Eastern Equine Encephalitis, or “Triple E,” is back in Massachusetts with a bite.

EEE is transmitted to humans by mosquitoes. In Massachusetts alone, three people have died of the virus since late July and he state recently announced the 12th human case.

Aside from taking preventative measures, such as wearing mosquito repellent and minimizing skin exposure, there is little concerned citizens can do, experts say.

That’s where the East Middlesex Mosquito Control Project and Central Massachusetts Mosquito Control Project come in.

Mosquito control projects in Massachusetts are voluntary. The projects provide treatments and preventative measures that help control the pest’s population in member communities.

All 10 MetroWest communities participate in these projects. However, there are a few nearby communities that don’t, including Grafton and Upton, which are at critical risk for the virus.

Treatments and preventative steps are also taking a bite out of budgets that are paying for ground spraying in both non-member communities and municipalities whose budgets for mosquito control could run short due to the outbreak, according to Katie Gronendyke, a spokeswoman for the Mass. Department of Agricultural Resources.

As of September 26, the department had “received requests for about $100,000 in ground spraying reimbursements,” Gronendyke said. The additional funding is sourced from a supplemental budget that is currently awaiting final action in the Legislature.

Fortunately, project officials say the ability to promptly spray in MetroWest communities has not been affected by the different funding sources.

“We build in extra capacity with anticipation of these types of events, so we are able to perform additional work without any unnecessary delays,” said Timothy Deschamps, the executive director of the Central Massachusetts Mosquito Control Project.

Experts also said it is hard to determine exactly why this mosquito season has been particularly bad and what caused the surge in EEE. Sam Telford, a professor of infectious disease at the Tufts University Cummings School of Veterinary Medicine and member of the Central Massachusetts Mosquito Control Project Board of Commission, thinks it may be due to an especially wet fall and winter, which likely created more places for mosquitoes to breed.

Moreover, EEE tends to appear on a cyclical basis, he said. Typically there is a two-to-three season outbreak, following a seven-year pause, Telford said. The Massachusetts Department of Public Health only detected EEE in a handful of mosquitoes the last few years, in contrast to more than 400 detections of mosquitoes carrying the virus this season, according to the state Department of Public Health.

Some of this year’s EEE detections were in mosquito species that are “more indiscriminate,” meaning they may feed on birds and people, which increases the potential for humans to contract the virus, Telford said.

Despite high concentrations of EEE in mosquitoes early this year, mosquito control projects are restricted from taking more drastic measures until there is a human case and a public health emergency is declared, Telford said. Even then, there are limitations.

One of the biggest challenges in controlling populations this year is that mosquito control projects cannot spray until after dark, Telford said.

“Private companies can spray whenever they want … Mosquito control cannot go out until it’s dark to reduce the impact on pollinators,” he said. “This has hindered the efficacy of the aerial sprays, in that it has been fairly cold at night, and the aerial sprays depend on having the mosquitoes active.”

Sumithrin, the EPA-approved chemical that is the main agent in sprays, is briefly in the air following application, said Brian Farless, superintendent of the East Middlesex Mosquito Control Project. The spray only kills active mosquitoes, and leaves no residue.

Each year projects try to get ahead of mosquito season. This includes larvicide treatments in and near wetlands, Telford and Farless said. Larvicide applications are generally more effective than spraying.

Despite this, it is like being on a “treadmill,” Telford said.

“Every time you treat a body of water, new mosquitoes come and lay eggs, and you have a new brood come up,” he said.” You can’t keep revisiting the same site every week, because there are so many sites to visit.”

Rather than outsourcing spraying to private companies, both projects that serve MetroWest own their ground spraying equipment, making it possible for them to be ready virtually immediately after an outbreak or public health emergency is announced.

“We can do [spray treatments] pretty quickly, it just depends on how much notice the town wants to give the residents,” Farless said.

Local public health departments have already started to plan improvements for next year.

Framingham Director of Public Health Sam Wong outlined three goals: “work with the state to refine policy recommendations at a local level so that local responses are consistent, work with the media to report more on personal precautions instead of just spraying [and]… explore more preventive work in the wetlands and swamps during spring.”

In the meantime, citizens need to be careful until the first frost, after which mosquito activity should decrease.

“People are working really hard to limit the outbreak,” Telford said. “It’s just that at a certain point there’s only so much we can do. We have to rely on public education.”

This story was originally published in MetroWest Daily News.

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