Warm weather blamed for earliest appearance of West Nile virus in Pa.

A warm winter means more mosquitoes are on the prowl. As a result, Pennsylvania is dealing with West Nile virus earlier than usual.

“This year we had our earliest incidence ever of a mosquito positive, which occurred on May 3,” said Amanda Witman, a spokeswoman with the Department of Environmental Protection. On average, the virus emerges around June 17, according to DEP data.

Witman says it’s too early to tell whether West Nile’s head start will make the virus more of a public health risk this year.

The virus has already turned up in mosquitoes in 28 counties — many in Southeastern Pennsylvania.

Here’s a map of reported incidences of West Nile virus in Pennsylvania this year.

Last year, the state reported seven cases in humans. But Witman says many more probably had it.

“Of those seven human positives, we guesstimate that about 1,000 people statewide contracted the virus,” Witman said. “The problem is, only one out of every five persons will actually experience symptoms of the virus.”

That’s not to say West Nile isn’t cause for concern, says Witman. The virus’s flu-like symptoms can cause problems for people with weakened immune systems.

The DEP says the best way to minimize risk is to eliminate areas of standing water on your property and to avoid exposure during peak mosquito times at dawn and dusk.

Hunting mosquitoes

Pennsylvania recorded the earliest incidence of West Nile virus in a Berks County mosquito in May.

But how exactly did they find it?

According to the DEP’s Witman, the agency catches a lot of bugs.

“We do surveillance throughout the state every day,” Witman said. “For example, so far this year we have collected 28,822 mosquito samples statewide.”

Witman says the mosquitoes are trapped in basins filled with putrid water and then shipped to Harrisburg for testing.

The agency monitors the state’s mosquito population through the end of October.