“Swine Flu and the Mexico Mystery,” my story on the swine-flu outbreak, is up at Slate. It looks at a question hotly pursued right now: Why does this flu seem to take a much deadlier course in Mexico than elsewhere so far? The answers will suggest much about what’s to come.
Of the two two qualities vital to a nasty pandemicm– to spread readily, and to be deadly, — this flu,a brand-new strain of swine flu, or H1N1, seems to possess the first: Evidence is high that it spreads readily among humans. In that sense, it’s an inversion of the bird flu. Bird flu terrifies infectious disease experts because it kills about half the humans that get it–but it has so far failed to develop the ability to jump easily from person to person.
This swine flu, meanwhile, does seem to spread easily by airborne transmission. But how deadly is it? Despite the 100+ deaths in Mexico, we don’t really know. And that’s is why epidemiologists are working frantically to figure out the Mexico mystery: Why do the death rates there appear to be so much higher than those in the United States? In Mexico, it has reportedly killed about 100 of the 1,600 official suspected cases; elsewhere, it has appeared to take a far milder course, with zero deaths out of the approximately 300 instances. There are several possible explanations for this discrepancy–any one, two, all, or none of these ideas could shed light on how deadly this virus might prove.