A deadly strain of bird flu could appear in the United States in the next few months as wild birds migrate from infected nations, Homeland Security Secretary Michael Chertoff said Thursday.
"There will be a reasonable possibility of a domestic fowl outbreak” as migrating birds mix with ducks, chickens and other birds in the U.S," Chertoff said. But he cautioned against panic, noting that the Agriculture Department has dealt with other strains of bird flu for years.
“If we get a wild bird or even a domestic chicken that gets infected with avian flu, we’re going to be able to deal with it, because we’ve got a lot of experience with that,” Chertoff said, speaking to newspaper editors and publishers.
“I can’t predict, but I certainly have to say that we should be prepared for the possibility that at some point in the next few months, a wild fowl will come over the migratory pathway and will be infected with H5N1,” he said.
The spring migration of birds from Asia to Alaska is expected to start next month, and this year it will encounter a beefed-up federal effort to look for bird flu.
The screening project, in Alaska and elsewhere, is expected to test five to six times as many birds this year alone as the government has screened since 1998.
Scientists worry that birds arriving in Alaska may bring in the H5N1 virus and pass it along to other birds, which will fly south this fall on a migratory route to the Americas.
If a bird flu case is confirmed in the United States, Chertoff said the Homeland Security Department would have specific plans to deal with it, including watching to see if it developed human health characteristics. “But it would not be time to push the panic button,” he said.
Scientists already had been watching for the strain in wild birds in Alaska and North American migratory flyways. But the effort is being dramatically stepped up this year, said John Clifford, chief veterinarian for the U.S. Department of Agriculture.
Scientists will study live birds, others that are found dead or killed by hunters, and environmental samples that might carry the worrisome form of bird flu. While most concern about birds flying south through the United States focuses on their Pacific route in the western states, other migratory paths will be included, Clifford said.
The goal is to test 75,000 to 100,000 live or dead birds this year, said the USDA’s Angela Harless. The testing, which also will include some Pacific islands, will focus on waterfowl and shorebirds.
At the same time, Clifford said, officials will continue to monitor other activities that may introduce the virus to the United States: importing and smuggling of birds.
Fears of infected poultry
The chief concern about H5N1 in wild birds is that the virus might make its way to some of the 10 billion or so chickens produced every year in the United States. That could damage the poultry industry and pose a hazard for people who work with chickens. Virtually all bird flu cases in people reported so far are blamed on close contact with infected poultry.
Because much of the U.S. poultry business is kept indoors, there is a lesser chance that chickens, turkeys and other birds meant for human consumption will mix with infected wild fowl, Chertoff said. “But you know, there will be a reasonable possibility of a domestic fowl outbreak,” he said.
Human cases are uncommon, but scientists worry that the virus may mutate into a form that can pass easily between people. That could lead to a worldwide flu epidemic.
It makes sense to focus the wild bird monitoring on Alaska, but migratory routes are so complex there’s no guarantee that Alaska is where the virus will first arrive in North America, or that it will follow recognized flyways from there, said Ken Rosenberg, director of conservation science at the Cornell Lab of Ornithology in Ithaca, N.Y.
Migrating birds can show up “virtually anywhere and come from virtually anywhere. That’s just the nature of birds and bird migration,” he said.
Rosenberg said H5N1 might not appear in an outbreak that kills many birds, but rather in isolated cases.
Illegal pet trade
Peter Marra of the Smithsonian Migratory Bird Center at the National Zoo in Washington said it’s clear migratory birds have played a role in spreading the strain elsewhere, and that Alaska is an important place to look for it. But that’s not the only way the virus could reach the United States.
“I would say movement of birds through the illegal pet trade is probably the most likely way it’s going to get here,” Marra said.
That’s just a guess, he quickly added, but there is precedent. Taiwan, where bird smuggling is common, confirmed last October that its first case of H5N1 appeared in birds smuggled from China. A Nigerian official also has blamed illegal poultry imports for delivering the virus to that country.
Clifford agreed that smuggling birds or bird products is a possible route into the country, and said the government will boost its anti-smuggling efforts as well. Those efforts include not only inspections at the border, but also teams within the United States that survey exotic food markets, live bird markets and restaurants for signs of illegal animals.
As for legal imports, virtually all live birds that enter the United States have to go through a 30-day quarantine and be tested for bird flu and other viruses, Clifford noted. The government doesn’t allow imports of birds from countries that have H5N1 in poultry flocks.