WASHINGTON — Scientists have discovered possible bird flu in two wild swans on the shore of Lake Erie, but it appears to be different from the muchfeared Asian strain that has ravaged poultry and killed at least 138 people elsewhere in the world.

It will take up to two weeks to confirm whether the seemingly healthy wild mute swans in Michigan really harbored the H5N1 virus.

Yesterday, the U.S. Department of Agriculture declared that initial testing had ruled out the so-called highly pathogenic version of H5N1 but that they could have a relatively harmless, low-grade H5N1 strain instead.

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

Yesterday’s announcement was the first reported hit from a massive new program to test up to 100,000 wild birds in an effort to catch the Asian H5N1 virus if it does wing its way to North America.

Were the highly pathogenic H5N1 to be found in any wild birds here, that could trigger additional security steps to prevent infection of commercial poultry flocks, as well as even more intensive monitoring.

Twenty mute swans from a Monroe County, Mich., game area were among the first new batches of tests because they were part of a state program to lower overcrowding of the nonnative species. That testing found the possibility of H5N1 in two of the swans.