2006-02-27-Bird flu watchers keep eye on AlaskaUnderstanding Avian Influenza
2006-02-27-Bird flu watchers keep eye on Alaska
In a few weeks, as the sun begins to warm and the days lengthen, the birds will start taking flight.
By the end of March, thousands upon thousands - ducks, geese, sandpipers - will begin their annual trek north, toward Alaska.
Scientists hope they won't be carrying the notorious bird flu virus with them.
But as world health officials look toward Europe in alarm, where bird flu is spreading among wild birds faster than anyone expected, some U.S. scientists are looking half the world away, to Alaska.
Alaska is the crossroads of three of the world's great migratory flyways. Birds from Asia and North America mingle here, winging across continents to find the perfect bird nursery. Predators are few, tasty insects plentiful and sunlit hours long enough for plenty of baby feeding time.
"Alaska in the summer is a great place to be a bird," said Rick Kearney, wildlife coordinator for the U.S. Geological Survey.
But this year, the ingredients that make Alaska bird paradise could also bring trouble. Scientists fear that the deadly strain of bird flu spreading from Asia could hitch a ride to Alaska on the wings of migrating birds.
Then, when summer ends and birds begin to fly south, birds infected in Alaska could fly south to the continental United States.
"The opportunity for movement of the virus is probably stronger here than anywhere else in North America," said Kevin Winker, an associate professor and curator of birds at the University of Alaska Museum in Fairbanks.
Winker has been testing birds for bird flu since 1998, drawn here by the chance to study more than 450 different bird species.
But in the past, Winker and his colleagues have tested about 1,500 to 3,000 birds a year.
This year's tally could reach 20,000.
Federal officials plan an enormous effort, partnering the University of Alaska with the federal departments of agriculture and the interior.
"That's the most logical place for avian influenza to show up," said Kearney, who also now co-chairs the Interagency Working Group for the Early Detection of Asian H5N1 in Wild Birds.
"All eyes are on Alaska."
H5N1 is the deadly strain of bird flu that first appeared in Hong Kong in 1997. A campaign to kill infected birds stopped the virus then, but it re-emerged in Asia in 2003. Since then, it has crept across Asia, killing people who became infected through contact with birds, usually chickens in their family flocks. So far, more than 90 people have died.
This year, bird flu has spread with greater speed, killing four people in Turkey. Just this month, the virus has showed up in birds in 13 different countries, from Nigeria to Italy to France.
As the sick birds have multiplied, so too has the alarm. Even the famous ravens who live in the Tower of London have been moved inside.
The spread of the virus among migrating birds still doesn't pose the same public health threat as the potential spread among people. Most flu experts agree that the greatest chance for bird flu to threaten U.S. residents will occur if the virus gains the ability to jump from person to person.
So far, that hasn't happened. Those who have fallen ill have had direct contact with birds. Scientists don't know when - or if - the virus will ever gain that ability. If it does, that would set the stage for a global epidemic, and it most likely would start in Asia.
But U.S. scientists believe the spread of bird flu among wild birds poses a danger.
"Many of the other diseases that pop up in public concern are sort of flavor-of-the-month club that don't kill a lot of people - Ebola, SARS, monkeypox," Winker said. A true flu pandemic could kill anywhere from 2-million to 100-million people worldwide, scientists estimate. "This disease is a real killer. We do need to keep our guard up."
Once the virus enters the United States in a few wild birds, it likely will spread to others. Wild animals could be threatened. So could commercial poultry and farm animals, although experts stress the risk of that is low.
Wild birds spread the disease easily among themselves because they carry the virus in their digestive tract. Water becomes contaminated, and then other birds get infected by eating and drinking there.
There are many bird flu strains, and usually waterbirds, such as ducks, geese and swans, carry them without becoming sick. But H5N1 is different. Dead swans in Italy and Greece have tested positive.
That's just one of the things that puzzles scientists. In summer 2005, the virus spread north and west across Asia, against migratory routes.
Since last fall, the spread among wild birds has followed those routes, but questions remain.
"I would have expected more outbreaks in Africa than we've seen, if wild birds were an effective spreader of the virus," Kearney said. "It could be that sick birds don't fly far - that they didn't survive long enough to finish their migration."
Or it could be that scientists know less about how birds migrate than they thought. Another possibility is that humans have transported infected poultry.
"Most of the spread is what people do wrong," said veterinarian Gary Butcher, professor of avian pathology at the University of Florida. "Moving chickens improperly from farm to farm, or moving chicken coops or feed trucks."
Butcher just returned from a trip to Russia, advising on how to make commercial chicken farms safer. In a few days, he leaves to do the same in Egypt, Turkey and Saudi Arabia.
"Everybody seems to be very, very nervous," Butcher said.
Scientists also are unsure what will happen if the virus comes to North American wild birds.
"There's been a lot of debate about the role that migratory birds are or might play in spreading the disease," said veterinarian Ron DeHaven, administrator of the Animal and Plant Health Inspection Service of the U.S. Department of Agriculture.
If the virus is found in Alaska, DeHaven says it would likely spread first down the Pacific coast, because more birds there migrate to Alaska. Winker, meanwhile, said it "will spread across North America quickly, because waterfowl cover the continent."
But veterinarian David Stallknecht, who has studied bird flu in wild birds for more than 20 years, took a different view. Stallknecht said the virus also could come to North America from the east, because migratory paths also cross in Canada.
"The farther that virus spreads westward in Eurasia, the more likely there would be potential contact with the East Coast," he said.
Still, Stallknecht said, if North American birds become infected in Canada, that doesn't mean they'll spread the virus south. Milder bird flu strains already follow a pattern, said Stallknecht, also an associate professor of population health at the University of Georgia.
"The high infection rates in North America are associated with northern latitudes," he said. "You get down to Georgia and Florida, and the prevalence is next to nothing."
Birds go north in summer, become infected, pass the virus to other birds, and then the outbreak dies down before they fly south, Stallknecht said.
If U.S. wild birds are infected, federal officials fear the virus could spread to commercial poultry. But they stress that the U.S. poultry industry, with its cooped chickens and separate farms, are far different from Asia's family flocks. U.S. chickens have less contact with both wild birds and with people.
"The potential for this virus to have an impact on commercial poultry production is significant," DeHaven said. "Having said that, we have been dealing with (milder) avian influenza viruses for decades . . . finding it, containing it, and eradicating it."
In Florida, commercial farms are home to more than 31-million chickens. State agriculture officials have nearly quadrupled virus testing of commercial farms, state fairs and other locations and plan to test about 15,000 birds this year.
Butcher said fear will likely hurt the poultry industry more than the virus itself. Although the virus is killed by cooking, poultry consumption has dropped in countries where the virus has appeared.
"No humans have gotten bird flu from migratory birds," he said. "No humans have gotten it from buying a commercial chicken. But it is causing a panic."