Scientists say they’re finding a large number of a certain species of mosquito in the Green Mountain State -- and it happens to be the kind that transmits Eastern equine encephalitis.
The species, Culiseta melanura, is the primary transfer agent between infected birds and humans.
Alan Graham, who studies mosquitoes with the Vermont Agency of Agriculture, said he’s found more of this kind of species in the state than ever before.
Particularly, Graham found large concentrations of the insect in traps he set up in Whiting, Vt. That town is near where two men died from EEE in Addison and Rutland counties.
“We know that there's virus in the environment and we know that we can reduce the risk if we can do some surveillance,” Graham said. “Mosquitoes are very good carriers of diseases, but they don't carry all diseases and usually the diseases have evolved with the mosquitoes.”
There are 45 different species of mosquitoes in Vermont, Graham said. This year, Graham found more Culiseta melanura, which lives and lays eggs in swamps. Other kinds of mosquitoes dropped in population, he said.
So far this season, he’s collected 1,483 Culiseta melanura. In 2008, he collected 48, showing a migration of the species to our region.
“I think there must be enough water in the wetlands, permanent wetlands, that this species is doing well,” he said.
The state first found EEE in deer in the fall of 2010. Only this year did the virus show up in humans.
“[Culiseta melanura] continues to produce a lot of mosquitoes despite the dry weather,” Graham said.
Though the population of the species is increasing, Graham said there’s no correlation between the increased number and Triple E cases.
However, because we know the bugs are here and surviving in our environment, we can study them and combat them harder next season.
“We can at least educate people that there is a risk out there and try to reduce the risk through other means,” he said.
Officials said ground and aerial spraying was effective in reducing the threat of EEE this season. They focused on Addison and Rutland counties where the EEE cases were reported, but health officials stress other mammals have tested positive for Triple E across the state.
Mosquitoes won’t fly if the temperatures falls below 50 degrees, but their eggs will survive the winter and will be ready to hatch next spring.