Deadly bird flu: out of sight, not out of peril
WASHINGTON -- Less than a year ago, Americans could barely turn on the television, surf the Internet or pick up a newspaper without finding a doomsday story about deadly avian flu.
By last November, President Bush had asked Congress for 7.1 billion to help develop a vaccine, stockpile antiviral medications and fund state preparations for a possible pandemic.
Now, with the disease still centered in Asia and the failure of migratory birds to spread the illness to Europe and North America, the H5N1 virus has dropped out of the media spotlight. The dearth of coverage has prompted some to think that the threat of a pandemic has passed.
Nothing could be further from the truth, however.
So far this year, a person dies from the disease roughly every four days, compared with about once every nine days last year, according to World Health Organization data. Of the 108 confirmed human cases of bird flu thus far this year, 73 have been fatal. That's up from 97 cases and 42 deaths in all of last year.
"We're as worried now as we ever have been," said Michael Osterholm, the director of the Center for Infectious Disease Research & amp; Policy at the University of Minnesota.
How it's transmitted
Avian flu currently is transmitted mainly from animal to animal, mostly among birds. People can contract the disease after contact with infected animals and -- in isolated cases -- infected humans.
The fact that the virus hasn't made its way to U.S. soil is of little comfort to Americans, because it could mutate into a form that spreads easily from person to person, making geographic borders meaningless.
Most bird flu deaths are clustered in Asia, where billions of wild birds, domestic birds and humans live in close contact, increasing the chances of infection.
Indonesia, which is fighting an epidemic of avian flu in poultry, is the world's hotspot. Three deaths as of Thursday upped the nation's number of confirmed human cases so far this year to 53, with 43 deaths.
Earlier this month, the Food and Agriculture Organization of the United Nations announced that tests on infected Indonesian poultry found that the virus wasn't mutating toward a more lethal strain. However, there have been isolated instances of person-to-person transmission in Indonesia. "But not in an explosive way," said Bruce Gellin, the director of the national vaccine program at the U.S. Department of Health and Human Services.
Health officials were surprised when flocks of migratory birds that had flown south to Africa and then back to Europe last spring didn't carry the H5N1 virus as expected. Neither did birds that wintered in Asia and flew to Alaska last summer to breed. International bird monitors also found no widespread deaths from the virus among migratory birds.
Many experts now think that wild migratory birds are only bit players in the spread of the disease. More likely culprits are humans who clean, feed and house infected domestic birds and those who prepare infected birds and transport them to commercial markets, said Rick Kearney, wildlife program coordinator with the U.S. Geological Survey.
Six companies are researching a cell-based flu vaccine that could be made available to everyone in the U.S. within six months of a flu outbreak. Each company is planning a U.S. production facility, but construction is years away.
Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, is optimistic that the pace of vaccine science has picked up in the past year. He's particularly heartened by recent data from several studies indicating that vaccinations against one subtype of H5N1 might provide protection against other subtypes.
"That has caught my attention," Fauci said. "Just looking at the baseline lab data, you wouldn't have guessed that."
He cited new research by John Treanor of the University of Rochester in New York, who presented his findings Oct. 13 in Toronto at a meeting of the Infectious Diseases Society of America. Treanor and his colleagues had studied people who'd received two vaccinations against the Hong Kong strain of the H5N1 virus in 1998. Each was vaccinated again this year with a booster shot to fight the strain found in Vietnam. A second test group received only shots for the Vietnam strain in 2005.
Researchers found that more people who'd gotten shots in 1998 and 2006 developed antibodies to fight the Vietnam strain than those in the second test group.
"We need more data, but the concept is rather encouraging because if you give prevaccinations with one subtype you actually prepare much better for a vaccination or an exposure to a different subtype," Fauci said.
Health officials also hope to have 26 million courses of the antivirals Tamiflu and Relenza by year's end, and 81 million courses -- enough to treat more than 25 percent of the U.S. population -- by the end of 2008. Antivirals lessen the effects of the flu. Viruses eventually can develop resistance to widely used antivirals, and that's already occurred in isolated instances with Tamiflu.
Gellin said it was unclear whether the development was clinically significant, but added, "It does raise the issue of the need to look at other antiviral candidates." HHS will issue 200 million in contracts to develop more antivirals. The agency is evaluating proposals, Gellin said.