NEW YORK (AP) _ 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.
A top U.N. health official said the deadly strain could arrive in the Americas within six to 12 months or even sooner.
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.
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.
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.
Still, the strain, which has been spreading rapidly in Asia and parts of Europe and Africa could show up in wild birds in the Americas soon, Dr. David Nabarro, the head of the U.N.'s bird flu project, said Wednesday.
``I think it's within the next six to 12 months,'' he said. ``And who knows _ we've been wrong on other things, it may be earlier.''
Nabarro reiterated the World Health Organization's warning that ``there will be a pandemic sooner or later'' in humans, perhaps due to H5N1, or perhaps another influenza virus, and it could start any time.
Rosenberg said H5N1 might not appear in an outbreak that kills many birds, but rather in isolated cases.
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.