The Falmouth Board of Health declared Eastern equine encephalitis, which has been found in Falmouth test traps in recent days, to be a public nuisance and joined the Falmouth Board of Selectmen in approving targeted truck spraying to kill adult mosquitoes in areas of town the Cape Cod Mosquito Control Project deems necessary.
These actions came at a special joint meeting of the two boards Thursday, August 8. Nearly 20 people attended, including local conservation agents.
The targeted truck spraying, which a central Massachusetts agency will conduct through a mutual-aid agreement with the control project, will begin in the overnight hours Wednesday, August 14, as long as it does not rain. The agency could return, weather permitting, to complete the single round of spraying Monday, August 19.
Falmouth Health Agent Scott McGann, along with Gabrielle E. Sakolsky, an entomologist and the control project’s assistant superintendent, presented key facts about the mosquito-borne virus, which amplifies in infected birds.
Levels of EEE in mosquitoes are high statewide, with the highest levels in Bristol and Plymouth counties, where birds carrying the disease to Falmouth likely originated, Ms. Sakolsky said, noting that her group regularly tests and treats about 400 sites for mosquitoes in Falmouth.
State-funded, widespread, aerial spraying in those off-Cape counties is taking place now to help keep the virus from amplifying in swamps and spreading in birds to the Cape and elsewhere, she said, adding that the control project will have new test results by Tuesday, August 13.
In the 2012 EEE outbreak, there were no deaths in areas where aerial spraying took place and some deaths in areas where spraying did not take place, the entomologist said.
“On Friday, August 2, we found EEE-positive Culex mosquitoes, a species that breeds in man-made containers and bites birds, near Falmouth Town Hall. We also found mammal-biting and bird-biting mosquitoes that tested positive for EEE in a cedar swamp in Woods Hole the same day,” Ms. Sakolsky said.
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To date, no human cases have resulted from the Falmouth findings, and while the health risk from EEE can never be zero, communities can take steps to minimize the number of mosquitoes and individuals can protect themselves from being bitten, Ms. Sakolsky said.
“EEE is a virus spread through the bite of an infected mosquito. In Massachusetts, the virus is most often identified in mosquitoes found in and around freshwater, hardwood swamps. EEE is a very rare disease, and since the virus was first identified in Massachusetts in 1938, fewer than 100 cases have occurred,” Mr. McGann said.
The virus will remain in mosquitoes and birds in Falmouth until the first hard frost, Ms. Sakolsky said.
When the risk level rises to high or severe, some communities impose a curfew on town-sponsored or school-related events that take place at dusk, but the health agent did not recommend that type of action at this time.
Increasing public education to reduce the risk of individuals being bit, however, will be a priority for the town, which might use the Barnstable County Sheriff’s Office’s reverse 911 system, as well as online and school communication tools, to inform residents.
To avoid mosquito bites, people should remain indoors during peak mosquito hours, from dusk to dawn; wear long sleeves, long pants and socks when outdoors; apply EPA-approved insect repellent when outdoors; and mosquito-proof their homes by draining standing water and installing or repairing screens, Mr. McGann said.
The first symptoms of EEE are fever (often 103 to 106 degrees Fahrenheit), stiff neck, headache and lack of energy. These symptoms show up three to 10 days after a bite from an infected mosquito. Inflammation and swelling of the brain, called encephalitis, is the most dangerous and frequent serious complication.
Crews found five samples of EEE-positive mosquitoes earlier this week at traps near Falmouth Town Hall (one sample), at Treetops Condominiums (one sample) and on Devil’s Lane in Woods Hole (three samples). The Woods Hole samples included a species of mosquito that bites humans and birds and is able to spread the virus, while the other two sites had samples of mosquitoes that bite humans and birds but cannot spread the virus, Ms. Sakolsky said.
The control project has already increased the number of traps and crews working in Falmouth swamps, spreading a chemical that kills mosquitoes still at the larval stage.
The targeted spraying, in which a truck drives along streets and through neighborhoods near the EEE-positive trap sites spreading a mist of the chemical Zenivex E4, will reduce the number of adult mosquitoes that might be carrying the virus, the entomologist said.
Zenivex, which is used throughout Massachusetts, New Jersey and Delaware, is considered an environmentally safe and low-toxicity insecticide. It targets small insects such as mosquitoes, midges and black flies but disappears within 48 hours and has no negative effects on vertebrate animals, Ms. Sakolsky said.
An additional precaution is that the spraying will be done overnight when other insects, including pollinators the chemical does not target, are not active, but Ms. Sakolsky said her team will communicate with the Barnstable County Beekeepers Association.
Members of the health board urged Falmouth residents to become educated about limiting the risks of EEE.
While some residents, companies and organizations might wish to spray their own properties or hire a contractor to do so, Ms. Sakolksy recommended that they contact the control group first for guidance so that they make intelligent choices about which contractors and products to use.