Berkshire County Tests Positive for West Nile Virus, Eastern Equine Encephelitis

Massachusetts environmental and public health officials are ramping up plans to spray insecticide at sites throughout Berkshire County. This is in response to mosquitoes testing positive for West Nile Virus — inclduing two reported in North Adams last week.

Last year, Berkshire County remained West Nile Virus free — at least officially — until September second, when one mosquito tested positive. This year, however, mosquitoes carrying the disease showed up in Pittsfield on June 26th — and more have been reported since. There have also been two positive results for the more dangerous Eastern Equine Encephalitis or Triple-E, in Pittsfield.

Christopher Horton runs Berkshire County’s Mosquito Control Project. He says the viruses are much more common in the eastern part of the state. But he says this year’s warm winter invited them west.

“And then we went into a dry period early in the summer and that reduced the surface water so that the mosquitoes that were trying to find a breeding spot and the birds that carried the diseases were in close proximity.”

Horton says Berkshire County Mosquito Control applies insecticide to mosquito larvae once the snow begins to melt each spring. But he says the disease has shown up in enough insects this summer to prompt another kind of treatment he calls “adulticide.”

“That’s the application of an insecticide that kills adult mosquitoes. The product it’s specifically made for mosquito control in populated areas so issues of toxicity and persistence and environmental concerns, they’ve all been figured in. But the problem is — we can’t treat the whole county.”

Horton says spraying is likely to take place in Pittsfield, Sheffield and Stockbridge in the coming weeks.