Mosquitoes test positive in Western Mass. counties

Date: 9/26/2023

While the risk map of the state Department of Public Health shows the dangers of West Nile virus and Eastern Equine Encephalitis are still low in Western Massachusetts, the yearly warning has more urgency this fall after insects in four towns tested positive.

“The state has been updating its warning about EEE and the increasing number of mosquitoes testing positive for WNV and EEE,” said Fran Fortino, chair of the Board of Health in Whately. “These last couple of cold nights are gonna knock down the numbers of mosquitoes … but they’re still here, and until a really hard frost comes we want people to try to avoid getting bitten during the most active hours, between dusk and dawn.”

Towns and cities can adopt an integrated pest management system or become a member of a mosquito control board. The Pioneer Valley Mosquito Control Board, the control board for Franklin, Hampshire and Hampden counties, operates under the State Reclamation Board, a part of the Department of Agricultural Resources. The control board was established in October 2017 and has been a touchy subject for many town accountants.

Mosquito control boards were made necessary after state law began to require towns have an integrated pest management system. Pest management plans are expensive to establish and run, with licenses required for applicators and onerous reporting requirements. Mosquito control boards offer another option. The fee for membership for a small town is $5,000 yearly, with extra charges for a variety of services related to mosquito control.

According to John Briggs, director of the Pioneer Valley Mosquito Control District, this year’s mosquito activity is concerning. Different mosquitoes than usual are carrying pathogens. Four towns, Brimfield, Sutton, Southbridge and Douglas have recorded infected insects.

“With the timing and the fact that multiple bridge vectors are coming back positive, I am a bit concerned that human transmission may eventually occur,” Briggs said. “We are technically not out of the woods until the first hard frost.”
The control district offers larviciding and adultciding services, sprayings that kill mosquitoes at different stages of life. The control district also works with towns to reduce mosquito prevalence by cleaning out roadside ditches and other places where water pools, offering mosquitoes a place to breed. Mosquito surveillance, early awareness of the presence of a pathogen in insects, is the initial defense.

The control district puts out traps in each member town. The traps capture mosquitoes, which are then tested by the Department of Public Health for EEE and WNV. Surveillance is critical, according to the control board’s web page, because the local board of health is notified when pathogens are discovered. Warnings are then issued to residents.

The dangers shouldn’t be ignored. The Bay State had several outbreaks over the last half decade. In 2018, Massachusetts had 49 confirmed human cases of West Nile Virus, one in Franklin County and two in Hampshire County. Two horses in Granby and Bernardston tested positive. In 2019, a Hampden County resident was infected with EEE and mosquitoes testing positive were trapped in Orange and Wendell.

The 2019 outbreak of EEE affected the whole state. Twelve human infections, including two in the Pioneer Valley, were recorded, as were nine cases of livestock infection, two in western Worcester County. Six aerial sprayings were conducted, and according to the website of the control district, the high risk of infections wrought heavy social and economic impacts due to canceled events.

The control district keeps track of mosquito activity and control efforts. The district monitors the effectiveness of the treatments used, which may include highly toxic solutions of glyphosate and other pesticides and herbicides, a controversial practice. The control district uses the data to better project each member town’s mosquito population and the most appropriate measures to prevent EEE and WNV. In some towns, residents may choose to opt out of treatments near their home.

“Avoid activities between the hours of dusk and dawn,” Fortino said. “Wear long sleeves if you’re going to be out during those hours and use some kind of bug repellent, DEET or something less toxic, like eucalyptus oil. If there’s standing water around the house, a bird bath or trough water for animals … you should drain it. Even rain gutters, which hold water” should be checked, Fortino said, because mosquitoes may breed there too.

More information on the Pioneer Valley Mosquito Control Board can be found at mass.gov/info-details/pioneer-valley-mosquito-control-district-pvmcd.