U.S. preparing for bird flu to arrive from eastern Asia
Migrating wildfowl expected to bring virus to Americas
Sabin Russell, Chronicle Medical Writer
Wednesday, September 28, 2005
Sacramento -- As world health leaders step up their warnings about a dangerous strain of bird flu in Asia, U.S. scientists are warily scanning the skies to the far north for signs of the virus in migrating waterfowl that cross continents and make their seasonal trips to the southern reaches of the United States.
The strain of bird flu known as H5N1 has yet to mutate into a form that can be transmitted easily among humans, but it already poses a threat to people in Asian nations who live in close proximity to ducks and chickens, and it would cause huge problems for the U.S. poultry industry if H5N1 became established in North America.
During the summer, the virus was apparently carried by migrating birds from China and Southeast Asia to Kazakhstan and Siberia, in the Russian Federation, where it subsequently infected domestic chicken flocks. The more entrenched the virus becomes in the world's bird population, experts believe, the greater the chances H5N1 will eventually mutate into a human disease.
Unlike seasonal flu, this influenza strain has been extraordinarily deadly for the few humans who have caught it from close contact with infected birds. Since December 2003, when the outbreak began, 115 people are known to have contracted it, and 59 of them died in four Asian countries.
At a meeting in Washington, D.C., with health leaders from North and South America on Tuesday, World Health Organization Director-General Dr. Lee Jong-wook declared that a pandemic was virtually inevitable. "There is a storm brewing that will test us all," he said. "We must anticipate it and prepare to the very best of our combined abilities."
At UC Davis Medical Center in Sacramento, doctors and bird veterinarians outlined efforts under way in California to monitor the dangerous H5N1 strain, which has yet to appear in birds in the Western Hemisphere, but is bound to create a scare if and when it does.
The focus is currently on Alaska, a junction where birds from the East Asia/Australian flyway -- encompassing areas infected with H5N1 -- can make a left turn and fly south along the Pacific Americas Flyway, which runs along the Pacific Coast, through California, all the way to the southern extreme of Argentina.
"Ducks, geese, gulls and terns are a natural host for these viruses," said Dr. Walter Boyce, executive director of the Wildlife Health Center at UC Davis.
He stressed that research so far has shown no evidence of any wild bird carrying the H5N1 virus in North America. But with the seasonal migrations of millions of birds now kicking into gear, Boyce said there is a concern that wild birds "will spread H5N1 around the world."
Dr. Carol Cardona, an avian flu and poultry expert at UC Davis, said the arrival of H5N1 will be problematic for chicken producers in the United States, but because birds here are raised under different conditions from those in Asia, it is less likely to wipe out vast flocks of domestic birds.
In Asia, farmers live in close proximity to many small flocks of birds where ducks, geese, chickens and pigs intermingle. In the United States, most poultry are raised in large commercial establishments that require standard "biosecurity" procedures limiting human contact with bird feces, which carry the virus.
Such biosecurity procedures have in fact worked in Asia. To date, the H5N1 virus has not turned up in the large poultry farms and processing plants that operate there, Cardona said.
In the United States, the arrival of H5N1 will necessitate tighter surveillance for bird flu, and flocks found infected would be "depopulated," the UC Davis veterinarian said. But she does not anticipate that orders would come down requiring the widespread slaughter of poultry -- even those that are raised in backyards and on hobby farms. As scary as this virus is, common sense procedures such as covering bird feed piles and keeping chickens under a roof can protect birds from virus dropped by wild, infected birds.
Dr. Warner Hudson, an infectious disease specialist at UC Davis Medical Center, stressed the importance of planning for the worst. "It's too big a bet not to prepare like crazy," he said. "For the first time, at least we have an early warning."
An experimental vaccine is being tested against the current strain of H5N1 flu, but the United States expects to produce no more than 20 million doses this year, and there is no guarantee it would work at all on a strain that passes easily among humans -- by definition, it would be a mutation of the current bug that is almost exclusively a disease among birds.
Stocks of an antiviral drug, Tamiflu, are woefully short of what would be needed to treat bird flu should it spring into a pandemic form. The federal Centers for Disease Control and Prevention have stockpiled enough to treat 2.3 million people. Hoffmann-La Roche, the Swiss pharmaceutical giant that is the world's sole supplier of the drug, has pledged to build a U.S. plant to produce Tamiflu before the year's end, but the drug supplies from that plant would not be ready until late 2006.
Should a deadly flu arrive in the United States -- and experts are not predicting when or if it would -- Hudson said that frequent hand-washing, the use of alcohol gel hand cleaners, and "respiratory etiquette" such as covering your nose when you sneeze are effective preventatives. "Stay home when you are sick," he advised.
Dr. Howard Backer, acting state health officer, said the California Department of Health Services is prepared for a pandemic, despite shortages of personnel in the state's Richmond virus lab, where samples of potential cases of bird flu would be tested. Backer said more than two dozen possible cases have already been evaluated, and all turned up negative.
E-mail Sabin Russell at email@example.com