FINKSBURG -- The start of one of Maryland's most popular hunting seasons gave state wildlife managers their first look at the effects of a deadly virus on the white-tailed deer population.

Biologists were at taxidermy and butcher shops yesterday for the first day of the two-day-early muzzleloader season to look at the health of deer and to ask hunters whether they have seen signs of epizootic hemorrhagic disease, a naturally occurring outbreak that happens every year on the East Coast.

"In a low-level year, no one even knows about it but us," Pete Jayne of the Department of Natural Resources said. "But this year, we're hearing about it. The early muzzleloader season and firearms season [next month], we'll start to see the impact."

So far, the state has confirmed cases in four counties, all on the Eastern Shore.

But V. Wilson Freeland, chairman of the governor's Wildlife Advisory Commission who lives in Calvert County, said crop damage in his area - especially in cornfields - seems to be down, perhaps a sign of the virus' progress.

"It's amazing how much deer damage has been reduced this summer," he said.

States surrounding Maryland are seeing outbreaks; in West Virginia, game officials have reported cases in 20 counties.

The disease, often fatal, is caused by the bites of midges, small flying insects that swarm around pools where deer go to drink. Droughts often exacerbate the situation by causing deer to congregate around shrinking ponds.

Infected deer lose their appetites as the virus attacks their blood clotting mechanisms. The animals have trouble breathing and sometimes salivate excessively. Deer that survive often look emaciated.

In a bad year, 25 percent of the state's deer population could die. The last serious attack in Maryland occurred in the early 1980s, Jayne said. But isolated outbreaks, such as one in 2002, killed 100 deer in Dorchester County.

Outbreaks usually occur in pockets, but rumors and exaggerations often spread statewide.

"We had a call from a farm on the upper [Eastern Shore] of 60 dead deer. I sent two biologists, and Natural Resources Police sent two officers. They found three carcasses," Jayne said. "Did they miss some? Yes. Did they miss 57? No."

candy.thomson@baltsun.com