Strain of flu virus in Michigan swans considered harmless

WASHINGTON — All year, the government has promised stepped-up testing to see if bird flu wings its way to the United States. On Monday, the Bush administration announced those tests got a hit — but the suspect isn't the much-feared Asian strain of the virus.

Scientists believe two wild swans on the shore of Michigan's Lake Erie harbored a relatively harmless version of the H5N1 virus instead.

If they're right — and it will take up to two weeks to confirm — then Monday became almost a dress rehearsal for the day the notorious Asian version of H5N1 really arrives in North America.

In almost the same breath, Agriculture Department officials announced Monday that routine testing had turned up the possibility of the H5N1 virus in the two swans — but that genetic testing had ruled out the so-called highly pathogenic version that has ravaged poultry and killed at least 138 people elsewhere in the world.

"We do not believe this virus represents a risk to human health," said Ron DeHaven, administrator of the USDA's Animal and Plant Health Inspection Service. "This is not the highly pathogenic avian influenza virus that has spread through much of other parts of the world."

Still, DeHaven said, it was important to be open with the public about preliminary results from the nation's massive program to test up to 100,000 wild birds for the virus.

Wild birds, especially waterfowl, are a natural reservoir for flu — they carry a multitude of influenza viruses. Sometimes, those strains jump species, and if it's a flu virus very different from one people have experienced before, a worldwide epidemic could result.

That's why scientists have closely tracked the virulent H5N1 strain since it began its global march in late 2003. It is blamed for the death or destruction of millions of birds overseas. Virtually all the people who have caught it did so from close contact with infected birds or their droppings. But scientists worry that the virus eventually could mutate to become easily spread from person to person.

Last week, the government expanded the bird-testing program to encompass the entire nation, after initial sampling mostly in Alaska. Twenty mute swans from a Monroe County, Mich., game area were among the first new batches of tests.