Areas treated after West Nile virus found
The state Department of Environmental Protection sprayed a thermal fog on Aug. 21 at a mobile home park and a sewage treatment plant in Greene County after mosquitoes infected with West Nile virus were found at one of the sites. Dustin Teegarden, the county conservation district’s West Nile virus coordinator, said test results received Wednesday from mosquito samples collected Aug. 5 from Reeseman’s Mobile Home Park in Morgan Township showed the insects were infected with the virus.
The fog also was sprayed as a precaution at the Waynesburg sewage treatment plant in Franklin Township where a large population of adult mosquitoes was found, but none had the virus, Teegarden said.
“Everything went well [with the spraying] at both sites,” Teegarden said Tuesday.
“The process took approximately one hour at each site, and as of today there have been no reports of sickness, incidents or problems.”
The active ingredient in the thermal fog mosquito adulticide is permethrin. It was to be applied at a rate of .007 pounds per acre between 7 and 10 p.m.
In that concentration, permethrin is not harmful to humans, livestock, pets, birds or wildlife, Teegarden said.
He said Ed Farrell, the DEP’s southwest West Nile virus coordinator, sprayed the fog using a hand-held device that appears similar to a leaf blower.
“It’s a hand-held device and creates a fog like (smoke from) a structure fire,” Teegarden said.
The thick, dense fog travels about 300 yards and residents living within 600 yards of the spray areas were advised to stay indoors, close their windows and doors, cover their vegetable plants and turn off their air conditioners for an after the fogging. Vegetables should be washed before they are consumed.
Barrier treatments, which involved spraying an insecticide containing deltamethrin to fencing and vegetation, were performed at Reeseman’s and the sewage plant last week, but they were not effective, Teegarden said.
Barrier treatments applied at Wana Be Park in Carmichaels and the county fairgrounds in Franklin Township on Aug. 7 were effective in killing adult mosquitoes.
At Wana Be Park, traps collected 92 mosquitoes before the barrier treatment and only five afterward, Teegarden said. At the fairgrounds, the numbers were 88 and three, respectively.
At the sewage plant, 141 mosquitoes were counted before the barrier treatment and 119 afterward.
“We’re not sure why it didn’t work (at Reeseman’s and the sewage plant), so we’re trying a different course of action,” Teegarden said.
None of the mosquitoes tested from Wana Be Park or the fairgrounds had the virus, he said.
After the fogging, mosquito traps were set up in a two-square-mile area around Reeseman’s and the sewage plant for 24 hours to measure its effectiveness. As of Tuesday, the results of the trapping had not yet been reported.
Since 2002, 11 birds and two mosquitoes from the county tested positive for the virus, Teegarden said.
The two weeks it took the DEP to test the mosquitoes collected from Reeseman’s and forward the results was because of the heavy load of testing the DEP does in Harrisburg, Teegarden said.
“They have a lot of samples to go through. They receive samples from every county in the state,” Teegarden said. “They have a lot of testing.”
People more than 50 years old are most susceptible to contracting the virus from mosquito bites, he said.
Property owners should eliminate all standing or stagnant water to prevent mosquitoes from breeding, Teegarden said.
Discarded vehicle tires are especially attractive breeding sites for mosquitoes because they keep water that collects in them warm during the day and night, he said, adding that a mosquito could develop from an egg into an adult in four days in such optimal conditions.
Only one in every 150 people infected suffer more than a fever, Teegarden said.
However, the virus can cause meningoencephalitis, inflammation of the brain and its surrounding membrane, and can be fatal, he said.
(Messenger Editor Steve Barrett contributed to this story.)