Washington ? City folks, don’t worry. Nobody expects pigeons, more common than manhole covers, will bring the deadly bird flu virus.

Pigeons are not immune from the virus. But tests indicate the birds pick it up only when they are exposed to very high doses, do not always become infected under those conditions and are carriers only briefly.

“Pigeons aren’t a big worry,” said Rex Sohn, a wildlife disease specialist at the U.S. Geological Survey’s National Wildlife Health Center in Madison, Wis. “But to make absolute predictions that pigeons won’t be susceptible to this virus, in whatever form it arises in North America, is not something you want to say.”

Government scientists looking for the first signs of the H5N1 bird flu strain in the United States are focusing on wild migratory birds, not resident birds such as pigeons, starlings and sparrows that stay close to home.

In February, a 14-year-old pigeon seller in Iraq died after coming down with bird flu-like symptoms. Authorities said three of his cousins also were hospitalized with similar symptoms.

There have been no pigeon die-offs in parts of the world experiencing H5N1 outbreaks, according to USGS wildlife disease specialist Grace McLaughlin.

Studies since the late 1990s by the Agriculture Department’s Southeast Poultry Research Laboratory in Athens, Ga., have shown that pigeons are not uniformly susceptible to the H5N1 virus, and that when they do become infected, they are only infectious for about two days.

“The experimental data is not very strong that pigeons are going to be spreading this virus around,” the center’s director, David Swayne, said.