BOSTON (AP) – For the first time in 16 years, Massachusetts will conduct aerial spraying to reduce the threat posed by mosquitoes carrying eastern equine encephalitis.
State health officials said Thursday the spraying will take place over 159,000 acres of land in southeastern Massachusetts. The operation could begin as early as Monday and will take place after sunset.
Frequent, heavy rains this spring and summer helped boost the mosquito population in the state and led to an earlier-than-normal appearance of the disease in mosquitoes, according to state officials.
More troubling is the fact the disease has been found in four different species of mammal-biting mosquitoes, according Dr. Alfred DeMaria, chief medical officer at the state Department of Public Health.
Those factors combined helped persuade health officials to go ahead with the aerial spraying, he said.
“If we don’t do something like this, we’re almost guaranteed to have some human cases,” he said.
The spraying will be concentrated in an area where the four different species of mosquitoes were found and which has traditionally seen heavy concentrations of the disease.
Although public health officials assured residents that the spray is safe, some areas within the spray zone will be excluded, including schools, day-care centers, organic farms, public water supplies and fish hatcheries.
Officials said they hope to complete the spraying in one night using two airplanes, if weather permits. High winds or rainstorms would likely cause a postponement in the spraying.
The chemical used is called Anvil. The active ingredient is sumithrin, a man-made form of the pesticide that occurs naturally in chrysanthemums. It has been used in residential areas and golf courses and breaks down rapidly when exposed to sunlight, officials said.
The exposure to humans is even less with aerial spraying than when chemicals are sprayed from a truck because the planes fly at about 300 feet.
DeMaria said that while the sumithrin is considered safe, the state will recommend people stay inside during while it is being spraying as a precaution.
The first case this summer of the virus in human-biting mosquitoes was discovered earlier this week in a horse the Lakeville/Middleborough area.
There were four human cases of the virus with two deaths both in 2005 and 2004.
State health officials urged people to minimize bug bites by applying insect repellent, wearing pants and long sleeves and getting rid of standing water where mosquitoes breed.
Since 1938, when EEE was first identified in Massachusetts, there have been 87 cases reported with 47 deaths.
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