The state Department of Agriculture has banned sales of birds at Maryland livestock auctions, and Carroll County egg producers are tightening "biological security" measures on their farms to prevent the spread of avian influenza in the wake of a recent outbreak in Pennsylvania.
The virus is not dangerous to humans, but it is nearly always fatal to chickens and other birds.
The current outbreak was detected during routine testing at a livestock auction in Philadelphia and at the Pennsylvania Farm Show in Harrisburg last month. The last major epidemic occurred in Pennsylvania in 1986. It cost the poultry industry $66 million.
"The potential danger in Carroll County is tremendous," said county extension agent David Greene. "There are close to a million birds here."
No Carroll County chickens have been infected, said Bill Satterfield, executive director of the Delmarva Poultry Industry Inc., a trade group that is coordinating the prevention effort.
Avian influenza has been found in one Maryland chicken, in a backyard flock in Caroline County, he said.
The virus usually is carried by humans or equipment that travel from farm to farm. Security measures used to protect chicken houses from the organism include disinfecting all trucks that visit the farm and prohibiting visitors.
"If I was an egg producer, I wouldn't let anybody on my farm at all, not even the meter reader," Mr. Greene said. "That's the kind of security you need, to even monitor the things you don't even think about."
Producers also have been warned about wild waterfowl that could carry the virus onto their farms.
"You've not only got the feed trucks, but birds flying overhead," Mr. Greene said.
The Department of Agriculture has banned all six licensed livestock auctions in Maryland from selling birds because the operations cannot guarantee immediate slaughter.
Johnny Arbaugh, a manager at the Westminster Livestock Auction, said the quarantine cut sales in half at the rabbit, poultry and produce sale Thursday. That auction usually moves between 200 and 250 birds weekly.
"We cannot sell feathered birds at all, from canaries all the way through," he said.
Other auctions that usually sell birds are the Woodsboro Auction in Frederick County, and the Friends and Grantsville auctions in Garrett County.
New York, New Jersey, Pennsylvania, Delaware, Virginia and West Virginia have also banned poultry sales at live markets.
"We were told . . . that the quarantine would be for 10 days, but with as many states as there are involved, it will be longer than that," Mr. Arbaugh said.
Maryland's ban will remain in effect until agriculture officials are sure that the virus is no longer a threat, said Roger E. Olson, assistant state veterinarian. "It all depends on the testing," he said.
After the infected chicken was found in Goldsboro, Caroline County, last week, the entire flock was destroyed and chicken production within a five-mile radius was placed on tighter security.
Delmarva, a poultry production trade group based in Georgetown, Del., is coordinating the precautionary effort, which is directed primarily at Eastern Shore broiler and fryer producers.
Carroll County's chicken industry is involved in egg production, and mostly under contract with large companies, Mr. Greene said.
"There are only layers in Carroll County," he said. "We have no broilers."