Scientists will not release the results of a first round of tests until a second round is complete, said Anne Fitzgerald, a spokeswoman for the Delaware Department of Agriculture. It was not immediately clear when the results would be released.
The flu strain is different from the one that has spread to the human population in Asia, and experts say there is no threat to human health. Some Asian countries, however, have banned U.S. poultry imports after the outbreak in Delaware.
On Saturday, Delaware authorities began testing flocks within a 2-mile radius of an infected farm in Kent County, where officials ordered the destruction Friday of 12,000 chickens. The farm's exact location has not been disclosed.
Japan, Malaysia, South Korea and Singapore banned U.S. poultry imports after the outbreak. Hong Kong banned importation of live birds and poultry from Delaware only.
Poultry growers on Maryland's Eastern Shore said yesterday that the farm where the outbreak occurred was not a grower for the region's four major exporting poultry companies - Perdue, Tyson, Mountaire and Allen Family Foods.
Worcester County Commissioner Virgil L. Shockley, a poultry farmer and a member of the governor's poultry task force, said the Delaware farm supplies a live poultry market in New York City.
Shockley said he believes the Asian countries had not examined the facts before imposing bans on U.S.-produced chicken. He also said there is a global shortage of poultry: "The world's kind of running out of chicken. You've got to realize they're not exporting from China, from Thailand, from Laos - they're killing chickens."
Shockley said he hoped marketing specialists in Delaware and Maryland agriculture departments would take quick action to spread the word that the Delaware farm was not a source of chicken for export.
Avian influenza spreads easily among animals through nasal and eye secretions, as well as manure. The strain found in Delaware, known as H7, has the potential to cause severe economic damage if it spreads to the commercial broiler industry, a linchpin of the region's agricultural economy.
A different form of bird flu has ravaged poultry farms across Asia, where more than 50 million chickens have been slaughtered. At least 18 people have died in Asia from the H5N1 strain. Experts there say there's no sign the virus is changing into one that could spread widely among people.
The U.S. government has banned the importation of birds from eight Southeast Asian countries.