Franklin County prepares for fight against West Nile

April 14, 2005|by DON AINES

CHAMBERSBURG, Pa. - With spring comes mosquitoes and, although the number of West Nile virus cases in Franklin County dropped sharply from 2003 to 2004, the annual detection and eradication program for the disease will soon begin.

The number of positive tests for the virus in this county fell from 47 in 2003 to six in 2004, according to Ray Eckhart, the county's West Nile coordinator. He said 2003 was the worst year in the state since the virus was first detected in 2000.

The number of humans testing positive decreased from six to one, with the other five positive tests coming from mosquitoes. The number of positive tests among birds and animals, mostly horses, fell from 33 in 2003 to zero last year, he said.


Increased detection and eradication and last year's abundant rains are the most likely reasons for the decrease, Eckhart said. Frequent rains flushed areas of stagnant water in which the culex pipiens mosquito that carries the virus breeds, he said.

"That's the gal we're looking for," said Eckhart, who noted only the female bites humans and other animals for the blood protein it needs to breed.

Last year the Pennsylvania Department of Environmental Protection conducted the West Nile program, according to Eckhart, who works for the Penn State Cooperative Extension Service.

This year the county received a $73,985 DEP grant to run the program and the extension service is being contracted to supply the personnel, according to Franklin County Commissioner Cheryl Plummer.

"There are definite places we need to monitor because they are known breeding areas," said Eckhart. Wetlands remote from populated areas, though, are not among them, he said.

The culex pipiens, he said, is a variety of mosquito that stays close to home and natural wetlands usually have predators that keep the mosquito population in check. Stormwater basins, tire piles and other sites where water collects will be monitored, he said.

That includes the collection of larval and adult mosquito samples that will be forwarded to DEP for testing. Where larvae are found in standing water, Eckhart said it will be treated, usually with Bti, a naturally-occuring bacteria that destroys larvae.

Spraying for adult mosquitoes is only done as a last resort in consultation with DEP, he said.

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