'Chicken Flu' Is No Big Peril

It's been a frightening year for flu. First came the dire predictions out of Southeast Asia, where the explosive spread of H5N1 avian flu among chickens, along with the deaths of about 40 people, has spawned fears that the disease could mutate and cause a worldwide pandemic. Next, there was the flu vaccine shortage. But so far, the flu season has been milder than usual. Gradually, the flu panic has subsided.

Until last week. Last Monday, despite the absence of new data, Julie Gerberding, director of the Centers for Disease Control and Prevention, revived the specter of flu catastrophe and sent it flapping around the world again. In an address to the American Assn. for the Advancement of Science, she reportedly said, "Every time there's a new [flu type], we get a new pandemic" -- an erroneous remark her spokesperson, Tom Skinner, denies she made.

She now says there is no immediate threat of a flu pandemic in the United States, but she's still peddling this basic position: The circulation of lethal bird flu in Southeast Asia, and the disease's ability to infect mammals, means that it will probably evolve to spread among people. When it does, we will have no immunity, because H5N1 is new to humans. And hundreds of millions may die.

In the past, new flu types from birds have indeed produced pandemics. In 1957-58, H2N2 flu spread around the world, causing 70,000 deaths in the U.S. In 1968-69, another variety, H3N2, killed about 36,000 in the U.S. -- comparable with a normal flu season. But these pandemics were mild compared with the only massively lethal flu pandemic in history, the 1918 flu, which killed between 20 million and 40 million people.

According to molecular biologist Jeffery Taubenberger, who has reassembled the genetic code for five of the eight genes of the 1918 flu, this disease did not come directly from birds. Still, the parallel between the 1918 flu (which killed, Gerberding reminds us, only 1% of the people it infected) and the present-day avian flu outbreak is constantly invoked. Infectious disease expert Michael Osterholm insists that because the planet is far more crowded and transportation more rapid than in 1918, H5N1 could cause the worst disease outbreak in history.

But this logic has more holes than a tennis racket. First, avian flu evolved to kill chickens, not people. It attacks people who drink infected chicken blood, wade in chicken feces or slaughter sick chickens for food. In other words, its human victims have typically been exposed to massive doses of chicken virus.