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Scare headlines about the possibility of a deadly flu pandemic have been with us for a few years now, ever since the H5N1 bird-flu virus that first appeared in Hong Kong in 1997 resurfaced in the region in 2003. But in the past month the drumbeat of such stories has grown faster and louder: Avian Flu Arrives in Poland. Turkey. Azerbajian. Germany. Denmark. And, just last Friday, Israel. The good news, according to Dr. Michael Osterholm, the director of the University of Minnesota's Center for Infectious Disease Research and Policy, is that the arrival of infected birds in North America—sometime this year, in the estimation of most experts—is not likely to result in large numbers of human infections with the virus, because most domestic poultry in this part of the world is raised in factory-farm isolation units that prevent contact with wild birds.
The bad news is that that's pretty much the only good news. What matters in judging the prospects for a human pandemic version of H5N1 (the name is shorthand for the chemical structure of two of the virus's key components, hemagglutinin and neuraminidase) is not so much the global reach of the bird version, but the question of if or when the virus mutates to a form that's easily passed from human to human. If that happens anywhere in the world, says Osterholm, the virus would likely start hitching rides with travelers and seed itself around the globe in a matter of days or weeks.
Of the hundred-plus human cases of H5N1 flu recorded so far, the vast majority have involved bird-to-human transmission, mostly among open-air poultry handlers in Asia. In addition, there are confirmed clusters in which it has passed from person to person, though none of those has yet resulted in a breakout of the virus. One thing is clear, however: In its present form, H5N1 has killed over half of the people it's infected. The great flu pandemic of 1918-19, by contrast, killed about 5 percent of its victims.
Will it cross over? If it does, can it possibly remain as deadly? Though Osterholm notes that viruses usually do lose strength as they spread—it's not really in their own evolutionary interest to kill the majority of their hosts—he believes the only responsible answer on both counts is we don't know. But it's not just the characteristics of the virus that worry him.
One of the things that sets the former Minnesota state epidemiologist apart from other public health officials is his attention to the fate of the medical and social infrastructure in any serious contagious outbreak. With respect to bird flu, his outlook recapitulates in many ways what he had to say in his 2001 book about bioterrorism preparedness, Living Terrors—much of the human toll in death, hysteria, and anarchy would be exacted not by infection but by the wide-scale breakdown of global supply chains and just-in-time delivery systems for vital goods and services. "I think [Health and Human Services] Secretary [Mike] Leavitt has been brutally honest in telling American communities, you're going to be on your own," says Osterholm. "And I think he's right."
City Pages: Let me start with the question of the likelihood of a global flu pandemic. Yesterday alone, I saw two wire service headlines with radically different-seeming implications, one indicating that the H5N1 avian flu is likely to go global within six months, and another speculating that the threat of human transmission may be passing as we speak. Is it possible to say, based on the epidemiological evidence, how likely a human flu pandemic is in the next six months, the next year, the next two years?
Michael Osterholm: First of all, let me take a step back and say that's a typical question we hear from the public. But it's almost like asking, how many apples can you harvest from the ocean? Because flu pandemics are like earthquakes, hurricanes, and tsunamis—they occur. There's going to be another one. There have been 10 in the last 300 years. What you're really asking, I think, is will it be H5N1? It's important to understand that when you're preparing for pandemic influenza, you're preparing for something that will happen. To say anything to the contrary would be like saying, now that Katrina's happened, we'll never have another hurricane like it.
Will H5N1 be the pandemic strain, and will it occur in the next six to twelve months? The answer is, we don't know. What is troubling about this virus is that this thing has continued to mutate from its earliest days, in Hong Kong in 1997. And what is very, very troubling to us is that it's mutating in very similar fashion to the way the 1918 virus did. We went back with the 1918 virus and found all eight genes of that virus in tissue samples—five from soldiers' pathology slides that had been stored away, three from the recovered corpse in Alaska. They didn't have any live virus, but they've been able to make the virus from those eight genes. And by studying that, they could determine how it actually mutated and jumped directly to humans from birds. It didn't go through other species as the 1957 and 1968 viruses did, where a bird and a human virus got together, most likely in a pig lot, because pigs happen to be the universal recipients for both [birds and humans].