Mosquito Borne Illness Policies: Opting Out, And In To Community Spraying

It’s officially mosquito control season, with Manchester and Essex Boards of Health establishing policies to monitor local risks of rare mosquito-borne illnesses from Eastern equine encephalitis (EEE) and West Nile Virus.

In Essex, the town’s BOH was informed in a June letter that the Massachusetts Executive Office of Energy and Environmental Affairs (EEA) had “determined that proof of ability to perform significant mosquito management and control measures is not sufficient” and denied the town’s petition to opt-out of the state’s mandated emergency spraying program that changed the state’s emergency mosquito spraying program from an opt-in to opt-out policy. 

Historically, Essex has voted overwhelmingly against joining the state’s regional mosquito control district for monitoring and voluntary spraying.  And in April, the Essex Board of Selectmen applied to opt out of state emergency spraying after resident concerns about spraying’s environmental impact on the marsh, pollinators, and residents’ health.  

Mosquito surveillance for EEE began on June 13.  Currently, Essex is at the lowest risk level (“Remote”) for EEE, according to the Massachusetts DOH.  Manchester’s risk level is slightly higher (“Low”).  Both towns currently have the lowest risk level for West Nile Virus.

A 2022 surveillance plan outlines the threshold for when state emergency spraying may take place and specifics about potential spraying.

The Essex Board of Health reminded residents that the mandatory plan will only take effect if the town has reached a “critical state,” which is constituted by the following guidelines:

For EEE:

1. Multiple measures indicating critical risk of human infection:

• Sustained high mosquito infection rates
• Time of season with enough time remaining for additional amplification of virus
• Weather conditions likely to increase risk (above average temperatures, above average precipitation particularly the prior fall and spring)
• Larger than average Culiseta melanura and Cq. perturbans populations

       AND

1. A single confirmed EEE human prior to late August (focal area based on exposure history not residence)

OR

1. Multiple animal cases clustered in time and space (focal area based on exposure history not residence)

For West Nile virus (WNV):

1. More than five human cases of WNV clustered in time and space (focal area based on exposure history not residence)

AND

1. Combination of the following factors indicative of persistent or increasing risk:

• Time of season with enough time remaining for additional amplification of virus
• Weather conditions likely to increase risk (above average temperatures, drier than average)
• Larger than average Culex pipiens/restuans populations

In 2019, during mosquito season, 10 people in Massachusetts were hospitalized with a mosquito-borne illness.  Four of them died, including a Manchester resident who had contracted EEE.  The man had worked in communities of Boxford, Topsfield, Essex, Gloucester and Manchester, so health officials were not able to identify exactly where the person was exposed.

That year, in the face of a “moderate” threat level, the Manchester BOH approved spraying.

The state’s mosquito control measures include aerial exclusion zones, with spraying exceptions for certified organic farms, commercial fish hatcheries/aquaculture, hemp fields, priority habitats for endangered species, and surface water supply resource areas.

Essex residents need not request individual exclusion forms, as the town does not belong to a mosquito control district and opting out of state emergency spraying is not an option since the town’s request was denied.

Manchester is a member of the Northeast Mosquito Control and Wetlands Management District, along with 31 other municipalities, at a cost of $42,500 per year.

At its meeting last week, the Manchester Board of Health shared its 2022 mosquito control plan.  Attending the meeting were Barry Noone, director of the Northeast Massachusetts Mosquito Control & Wetlands Management District and Kimberly A. Foss, an entomologist for the district.  The pair offered details on the plan. 

One resident asked about the protocol’s impact on bees and other pollinators and was told if spraying were deemed necessary, it would be completed at night when bees are typically dormant.   Another resident asked in the event of spraying if a detailed schedule would be made available so those in homes that choose to can close their windows. 

She was told residents would know the day of the spraying, which would occur overnight, but it would not be possible to provide a specific window of time when spraying would take place.