WASHINGTON -- The recent discovery of bird flu in commercial ducks in western Canada raised red flags in the United States, but last week the U.S. government reduced import restrictions on live birds and poultry products from mainland British Columbia.
The new restriction was confined to a five-kilometer zone within the province, according to a decision by the U.S. Department of Agriculture's Animal and Plant Health Inspection Service. Bird flu was found in commercial ducks in that region Nov. 19.
"Because the pathogenicity of the virus was initially unknown, APHIS restricted imports from all of mainland British Columbia," said John Clifford, chief veterinary officer, APHIS, in a statement. "The Canadian Food Inspection Agency has since confirmed that the virus is one of the low pathogenicity forms of AI [avian influenza]."
Incidents of low pathogenic avian influenza are commonly detected in domestic poultry flocks and pose no known serious threat to human health like some strains of high pathogenic avian influenza, according to the USDA.
The trade restrictions haven't affected the U.S. poultry supply. "The U.S. doesn't import a lot of poultry or bring in a lot [of poultry] from Canada," said Jim Rogers, spokesman, USDA.
In fact, the amount of poultry imported to the states from Canada is miniscule, according to Richard Lobb, spokesman, National Poultry Council, Washington. "Even if poultry import restrictions were imposed on all of Canada, it wouldn't make a difference," he said. Still, the virus detected in the two Canadian birds raised concerns in the United States, since the illness proved to be the H5 strain of the virus. Both the H5 and H7 strains of low pathogenic avian flu can mutate into highly pathogenic forms of the disease. HPAI causes a severe and highly contagious illness and death among infected birds, according to the USDA. Some strains of HPAI can be infectious to humans.
Detection of the H5 strain, and not British Columbia's proximity to the United States, was the most alarming aspect of the incident, according to Rogers. "Whenever the [H5 strain] is detected anywhere in the world it's cause for concern," he said.
The incident has not affected poultry pricing or purchases in the states, according to Lobb.
"Americans are very confident of their food supply," he said. "They know all poultry is inspected and they can rest assured if there was a problem [related to bird flu] we'd stamp it out and none of those birds would make it to market."
APHIS randomly tests non-commercial migratory birds for bird flu, as do Canadian officials. APHIS also works in cooperation with state animal health officials to conduct surveillance at breeding flocks, slaughter plants, live-bird markets, livestock auctions and poultry dealers.
"APHIS currently has an interlocking system of safeguards in place to protect the U.S. poultry industry from AI," Clifford said, "including trade restrictions as appropriate as well as ongoing federal-state industry surveillance, emergency pre- paredness and outreach programs to ensure early detection and rapid response to any signs of the virus."
The United States reduced its British Columbia import restrictions last week because it was satisfied with the precautions being taken by Canadian authorities, said Rogers. He doesn't know when the restrictions will be completely lifted.
"The AI found in British Columbia was detected through ongoing surveillance efforts in Canada, much like the survey efforts that are in place in the U.S.," Clifford said in a statement. The British Columbia surveillance zone includes all 78 farms within five kilometers of each of the two infected premises, a precaution that is consistent with international and animal disease control guidelines, according to the CFIA.
Birds are tested in a random sampling conducted on the farms once a week, according to CFIA. Testing will cease on individual farms once birds on a particular farm receive negative results for bird flu during three consecutive weeks of testing.
Both farms where the virus was detected have been completely depopulated and the carcasses are being composted on site, according to the CFIA.
"We've taken the extraordinary measure of eliminating these birds because of the [H5] strain," said Ron Lewis, provincial veterinarian for British Columbia. "We're concerned about human health whenever it comes to the H5 and H7 strains."
In spring 2004, both low and high pathogenic forms of the H7N3 bird flu virus were detected on a farm in British Columbia. Further testing detected AI on 42 commercial and 11 backyard premises in the region. Seventeen million birds were destroyed in order to eradicate the disease.
Bird flu viruses can infect chickens, turkeys, pheasants, quail, ducks, geese and guinea fowl, as well as a wide variety of other birds. Migratory waterfowl have proved to be a natural reservoir for low pathogenic bird flu, according to the USDA. AI is primarily spread by direct contact between healthy birds and infected birds, and through indirect contact with contaminated equipment and materials, according to the USDA. Contact with fecal matter is the most common of bird-to-bird transmission. It can also occur via airborne secretions.
There is no evidence that HPAI currently exists in the United States. There have been three U.S. outbreaks of poultry in the U.S., in 1924, 1983 and 2004. No significant human illness resulted from these outbreaks, according to the USDA.
