WEATHER conditions have unleased mosquitoes bearing the West Nile virus sooner than ever, authorities say.

The first virus-infected mosquito of the season was found in Berks County on May 3 — the earliest detection in Pennsylvania since 2000.

The state Department of Environmental Protection, which monitors the virus in mosquitoes from May to October, has found 112 positive mosquitoes this year and reports that the numbers have been steadily increasing.

Last year, 1,262 mosquitoes and six humans were found virus-positive in 25 of the state's 67 counties.

"We anticipate the numbers to be similar to last year," said Pennsylvania DEP spokeswoman Amanda Whitman. "Not having a very severe winter is a contributing factor because not all of the adult population of mosquitoes was killed off. This year, the mild winter and wet spring caused an early emergence [of mosquitoes]."

This past May was the fifth-warmest May for Pennsylvania, and conditions were wetter than average, according to National Climactic Data Center climate scientist Jake Crouch.

"I think it's more complicated than [heat]," said Roger Nasci, chief of arboviral disease for the Centers for Disease Control and Prevention. "It was also the early spring that started the transmission season earlier than normal. We didn't have cold snaps or heavy frosts into the spring, so we had a longer growing season."

Virus symptoms can range from fever and rash to coma, vision loss, meningitis and death. However, up to 80 percent of human West Nile virus cases do not show symptoms, the CDC reports.

Nasci said that although the risk is greater among older people, the virus is not absent in infants. He also does not advocate the myth of light-colored clothing serving as a shield against virus-carrying mosquitoes.

"I haven't seen a whole lot of convincing scientific evidence of light-colored clothing, but long sleeves will definitely ward off mosquitoes," he said.

Residents are advised to reduce the risk of the virus by eliminate standing water such as bird baths and by chlorinating swimming pools. Peak exposure times to avoid are dawn and dusk.