FAIRBANKS, Alaska -- Beneath a dim morning sky, Jonathan Runstadler trudged across the ice with a long fiberglass tube, gardening tools, and a smattering of plastic lab bottles.
Months earlier, summer breezes had carried wild birds from Asia to this little pond. Now, with the temperature hovering at 9 degrees, Runstadler bored through the frozen surface in search of the seeds of a pandemic.
''Ground zero is what's in birds," said the University of Alaska molecular biologist, who dropped hockey puck-shaped ice samples into a Ziploc bag.
This snowy patch of the Alaskan wilderness sits at the edge of a bird flu outbreak that emerged in Hong Kong in 1997 and has recently spread as far as Kazakhstan, Croatia, and Siberia.
The virus has ravaged farms in Thailand and felled wild birds from China to Eastern Europe. It has killed at least 76 people in its march across the globe -- more than half of them in the past year.
What Americans once viewed as a distant scourge is now just across the Bering Strait. If it arrives in North America, scientists expect to find it first in Alaska, the breeding ground for many migratory birds from Asia.
The bird flu virus, known as H5N1, is the culmination of random mutations and countless viral mixings, producing a strain of influenza unfamiliar to the human immune system.
It could be just a few more mutations away from being able to infect and spread among people -- the raw ingredients needed to spark a global pandemic. Or it could evolve into a harmless strain.
Its future is uncertain. The virus is not so different from the common flu that causes fevers and runny noses each winter. Yet it has provoked a degree of fear that belies its mundane origins.
Governments have slaughtered millions of chickens and other poultry. Hospitals are stockpiling Tamiflu and other antiviral medications. Scientists are racing to develop a vaccine.
In Alaska, scientists such as Runstadler are searching for traces of H5N1 in bird droppings left from the summer breeding season. They could be preserved in the now-frozen water or soil.
''It's just a matter of time before H5N1 shows up everywhere," said George Happ, a biologist at the University of Alaska who is coordinating the state's pursuit of the virus.
The virus resurfaced in Asia in 2001 and has been spreading steadily from its epicenter in southern China since 2003. Vietnam, Thailand, Cambodia, Indonesia, and China have reported 36 deaths this year.
There have been 146 documented human cases, each of which increases the possibility of a deadly mutation.
Researchers have traveled to places like Chevak, Alaska, in search of H5N1. In July, Runstadler flew to these tidal flats to spend a week testing black brant geese for signs of the virus. The birds were molting, making them easier to catch.
The researchers can't tell whether an individual bird came from Asia, but they know that some of the species they are monitoring -- including brant geese, pintails, mallards, and godwits -- migrate from the other side of the Pacific.
''It's good to get anything we can because we're starting from a knowledge base of essentially zero," Runstadler said.
Government officials thought they could contain the spread of H5N1 by culling millions of farm birds. That notion now seems quaint, since wild birds have become a permanent natural reservoir for the virus.
Detecting the first signs of H5N1's arrival in Alaska will give farmers and public health officials crucial time to ready their defenses, said Dr. John Clifford, chief veterinarian at the US Department of Agriculture.