Eastern equine encephalitis threat prompts closure, spraying in Pachaug State Forest

By Janice Steinhagen - Staff Writer
Voluntown - posted Thu., Aug. 29, 2013
Pachaug State Forest around the Mount Misery and Frog Hollow horse campgrounds where closed on Aug. 27 due to trapped mosquitoes testing positive for eastern equine encephalitis (EEE). Those campgrounds will remain closed until further notice. Courtesy photo. - Contributed Photo

State officials closed Pachaug State Forest around the Mount Misery campground on Aug. 27 and conducted ultra-low volume pesticide spraying throughout 300 acres of the forest, after mosquitoes trapped in the forest tested positive for eastern equine encephalitis (EEE). The spraying program came a week after the Department of Energy and Environmental Protection closed both the Mount Misery and the nearby Frog Hollow horse campground in the park.

DEEP spokesperson Dwayne Gardner said that about 800 infected mosquitoes were found in seven different traps at various locations throughout the state forest. “The amount of mosquitoes we’re finding is high for this time of the year,” he said.

Triple E “doesn’t usually peak until mid to late September,” said Dr. Theodore Andreadis, chief medical entomologist for the Connecticut Agricultural Experiment Station. Trapping began in June, and the first infected mosquitoes, a bird-biting variety, were found in traps in July. But on Aug. 13, human-biting mosquitoes found in the traps tested positive for EEE. “Knowing what we have right now, there is the potential for [EEE] to build” through the rest of the season, he said.

The DEEP used pickup trucks to apply a spray of Resmethrin, a synthetic-pyrethroid-based compound with the brand name Scourge. Paul Capotosto, a natural resources program specialist for the DEEP, said that the spray would encompass about 10 miles of roads within the Mount Misery section of the forest. The spray was intended to kill adult mosquitoes on the wing during their most active time of day.

“We know we’re not going to get full coverage of the forest. We hope to just contain the virus,” said DEEP Mosquito Management Coordinator Roger Wolfe. Spray trucks would not be able to negotiate the forest’s narrow foot trails, he said. The agency plans to continue trapping and testing mosquitoes through the end of October, when frost typically eradicates the insect for the season. If infected insects continue to appear, “we’ll probably be back and [spray] again,” he said.

Both horses and humans can be sickened by the mosquito-borne EEE virus, which Andreadis called “the most deadly mosquito-borne pathogen in North America.” Some human cases manifest no symptoms, but according to Andreadis, “even if you survive the infection, more often than not there is severe neurological damage. The fatality rate is approximately 30 percent. It’s a potentially deadly disease,” he said. Children and those over age 50 are most at risk, he said.

Andreadis said that cases of humans contracting EEE have occurred in Massachusetts, central New York and Rhode Island in recent years. He said the disease is slowly spreading its range northward as far as Canada, and climate change may be playing a role in the disease’s spread. “It’s a virus on the move," he said.

Mosquitoes will move out and bite within a 2-mile range of the swamp sites where they breed and hatch, said Andreadis. “The greatest risk is during the early evening hours, in shaded woodland areas” or even under overcast skies.  Local residents are advised to avoid going outdoors during the early evening and to wear insect repellant. Sunny and windy conditions and midday temperatures tend to disperse the insects, he said. Getting rid of standing water can help eradicate mosquito habitat and slow the spread of all insect-borne illnesses.

“Horses are particularly susceptible” to EEE, said Gardner. An equine vaccine exists for the disease, but there is still none approved for use in humans. The state has seen just two equine cases of EEE in recent years, but no human cases, “which is fortunate, because it’s been all around us.” Still, he said, state officials decided to err on the side of caution. The forest will remain closed to the public until further notice.

“We know it’s an inconvenience for the public, but we want to avoid anyone getting sickened,” said Andreadis. “Why put yourself at risk?”

Both the Green Falls campground in Pachaug State Forest, 3 miles east of Voluntown on Route 138, and the Hopeville Pond State Park campground on Route 210 in Griswold remain open.

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