Frost Eliminates

West Nile Virus Threat

By Kaaren Valenta

Monday night’s heavy frost has eliminated the threat of West Nile Virus in Newtown – at least until next spring, according to Mark Cooper, director of the Newtown Health District.

“Our mosquito season is over,” Mr Cooper said. “I called [public works director] Fred Hurley to congratulate him. Our efforts to combat the threat of West Nile by applying larvicide throughout the year has been effective.”

This week state scientists said one dead crow from Newtown has tested positive for the West Nile virus, but Mr Cooper said the report was not significant now. “It shows the crow was bitten by a bird-biting mosquito that carried the virus, and usually you can begin to see human-biting mosquitoes that carry the virus about two weeks later. But our traps did not show any human-biting mosquitoes with West Nile. In any case, it is meaningless after the first frost.”

Twice this year local officials directed the application of larvicide in the 4,000 roadside stormwater catch basins in Newtown and Sandy Hook to combat the spread of the mosquito-borne West Nile virus. Mosquito larvae breed in the stagnant water found in catch basins, among other places. The larvae evolve into mature mosquitoes that carry the virus.

This year’s mosquito-control program was similar to last year’s project, which was useful in controlling mosquito breeding, Mr Cooper said.

Town workers dropped doughnut-shaped larvicide tablets into the 4,000 catch basins in the two rounds of larvicide application last year and also in the initial round of larvicide application this year in May. In the second round of larvicide application this year, workers placed a small scoopful of granulated larvicide into each of the basins.

The doughnut-shaped tablets tended to float on water and required weighting to be effective. The granulated material sinks to the bottom of standing water in the catch basins and is thus more easily applied.

Both the tablets and the granular material are the same bacteriological agent, Bacillus sphaericus Serotype, which is sold in large bags under the trade name VectoLex CG.