No mosquitoes test positive for West Nile — yet

No mosquitoes tested positive for West Nile virus during the first week of the state’s trapping and testing program.

From now through October, the state is testing mosquitoes for a variety of diseases, including West Nile, Zika and Eastern Equine Encephalitis. The Connecticut Agricultural Experiment Station released its results from the first week of testing on Tuesday. During that time, the state tested 13,629 mosquitoes at 92 trapping stations through Connecticut.

That volume of mosquitoes is “about average” for this point in the season, said John Shepard, assistant scientist with the Connecticut Agricultural Experiment Station.

No mosquitoes tested positive for West Nile, though one pool of the critters, in Canaan, tucked into Connecticut’s northwest corner, tested positive for Jamestown Canyon virus, which Shepard said is an emerging infectious disease that was discovered in Colorado in 1961.
“It’s on the rise” in this region, Shepard said, adding two human cases of Jamestown Canyon virus have been reported in Connecticut — one last year, and one in 2001. Nationwide, 166 human cases of the illness have been reported between 2000 and 2018.

Like West Nile and other mosquito-borne illness, Jamestown Canyon causes mild, flu-like symptoms in most people, but can cause more serious illnesses, such as meningitis and encephalitis.

Last season was the worst on record for prevalence of West Nile in Connecticut, according to the agricultural station. A total of 393 positive mosquito samples were collected from 65 sites located in 53 municipalities. The state reported 23 human cases of West Nile, and one death — the first since 2006.

Shepard said it’s not unusual to not see much disease activity in the first week or so testing. “Typically, we’ll start to see it pick up around mid-July,” he said.