Flu Fighters

A team of young Columbia scientists discovered the genetic origins of H1N1 swine flu this spring. Now they’re racing to determine its deadly potential.

by David J. Craig Published Fall 2009
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Only a few pigs have been found with the new H1N1 virus, as of this September, but Rabadan insists that’s probably because we’re not looking hard enough. Most countries, including the United States, do not require farmers to test swine for influenza.

“Improving flu surveillance in pigs should be the first lesson we take away from the genetic history of this new influenza,” he says. “For too long we’ve ignored the fact that these animals are a breeding ground for dangerous disease.”

Patient killer?

In the first few weeks of the swine flu outbreak, Mexico reported an unusually high number of flu-related deaths, leading global health officials to fear that they were confronting an illness perhaps as virulent as H5N1 bird flu. New York City shut down several schools, China quarantined travelers from Mexico, and Egypt attempted to slaughter all of its pigs. News media speculated that swine H1N1 might cause a pandemic as deadly as the 1918 Spanish flu, which killed 50 to 100 million people in a catastrophic epilogue to the First World War.

As swine flu spread across the world, though, health officials gradually realized that the vast majority of human illnesses are mild, that the illness is treatable with antiviral drugs like Tamiflu, and that Mexico initially had underreported its total number of nonfatal cases, which made the death rate appear higher than it was. Our bodies, despite swine flu’s posing a novel threat, seem to fight off the illness as easily as they do an ordinary seasonal flu. “Our immune systems are responding to this unfamiliar virus on the fly,” says Rabadan, “and in the time that we’re building antibodies, the virus just doesn’t seem that interested in hurting us.”

However, this flu is unusually contagious, which is to be expected, scientists say, of a virus to which we have no previous exposure. Given its infectiousness, swine flu could rack up a formidable death toll, even in its current mild form. The disease will kill more people this winter than a seasonal flu typically does, WHO predicts, in part because an approved vaccine is not expected to be available before October.

So is there any reason we should be more fearful of catching swine flu than a regular seasonal flu? Is there reason to suspect that it will become more virulent? Yes, says Rabadan: “Swine flu is going through an enormous number of variations in the human body right now, trying to see what works best. Every genetic change is a big roll of the dice.” A seasonal flu, on the other hand, develops a sort of equilibrium with its host. “There’s a history of our immune system fighting off the virus strain,” Rabadan says, “and a history of the virus going through lots of mutations until it figures out a general form that works for its survival.”

Research on other flu pandemics shows that reassorted viruses have become more virulent as they’ve spread. For instance, Stephen S. Morse, a professor of clinical epidemiology at the Mailman School of Public Health, has analyzed clinical data collected in 1918 and determined that the Spanish flu caused a wave of mild illness in New York City months before it started killing millions. Flu viruses may evolve to become more deadly, some scientists have hypothesized, because if they remain in a host’s body for a long time, they increase their chances of infecting others.

“Influenza is always unpredictable,” says Morse, who directs Columbia’s Center for Public Health Preparedness. “But I’ll tell you this: I’d rather catch this swine flu now than later.”

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