and they know that it’s a terrifying thing (though they may confuse it with E. coli, the bacterium that can kill you if you eat the wrong spinach). They are concerned. They are vaguely aware. But they don’t have the time or the interest to consider a lot of scientific detail. I can say from experience that some people, if they hear you’re writing a book about such things—about scary emerging diseases, about killer viruses, about pandemics—want you to cut to the chase. So they ask: “Are we all gonna die?” I have made it my little policy to say yes.
Yes, we are all gonna die. Yes. We are all gonna pay taxes and we are all gonna die. Most of us, though, will probably die of something more mundane than a new virus lately emerged from a duck or a chimpanzee or a bat.
The dangers presented by zoonoses are real and severe but the degree of uncertainties is also high. There’s not a hope in hell, as Robert Webster pungently told me, of predicting the nature and timing of the next influenza pandemic. Too many factors vary randomly, or almost randomly, in that system. Prediction, in general, so far as all these diseases are concerned, is a tenuous proposition, more likely to yield false confidence than actionable intelligence. I have asked not just Webster but also many other eminent disease scientists, including some of the world’s experts on Ebola, on SARS, on bat-borne viruses generally, on the HIVs, and on viral evolution, the same two-part question: (1) Will a new disease emerge, in the near future, sufficiently virulent and transmissible to cause a pandemic on the scale of AIDS or the 1918 flu, killing tens of millions of people? and (2) If so, what does it look like and whence does it come? Their answers to the first part have ranged from Maybe to Probably. Their answers to the second have focused on RNA viruses, especially those for which the reservoir host is some kind of primate. None of them has disputed the premise, by the way, that if there is a Next Big One it will be zoonotic.
In the scientific literature, you find roughly the same kind of cautious, informed speculation. A highly regarded infectious-disease epidemiologist named Donald S. Burke, presently dean of the Graduate School of Public Health at the University of Pittsburgh, gave a lecture (later published) back in 1997 in which he listed the criteria that might implicate certain kinds of viruses as likeliest candidates to cause a new pandemic. “The first criterion is the most obvious: recent pandemics in human history,” Burke told his audience. That would point to the orthomyxoviruses (including the influenzas) and the retroviruses (including the HIVs), among others. “The second criterion is proven ability to cause major epidemics in non-human animal populations.” This would again spotlight the orthomyxoviruses, but also the family of paramyxoviruses, such as Hendra and Nipah, and the coronaviruses, such as that virus later known as SARS-CoV. Burke’s third criterion was “intrinsic evolvability,” meaning readiness to mutate and to recombine (or reassort), which “confers on a virus the potential to emerge into and to cause pandemics in human populations.” As examples he returned to retroviruses, orthomyxoviruses, and coronaviruses. “Some of these viruses,” he warned, citing coronaviruses in particular, “should be considered as serious threats to human health. These are viruses with high evolvability and proven ability to cause epidemics in animal populations.” It’s interesting in retrospect to note that he had augured the SARS epidemic six years before it occurred.
Much more recently, Burke told me: “I made a lucky guess.” He laughed a self-deprecating hoot and then added that “prediction is too strong a word” for what he had been doing.
Donald Burke can be trusted on this as much as anyone alive. But the difficulty of predicting precisely doesn’t oblige us to remain blind, unprepared, and fatalistic about emerging and re-emerging zoonotic diseases. No. The practical alternative to soothsaying, as Burke put it, is “improving the scientific basis to improve readiness.” By “the scientific basis” he meant the understanding of which virus groups to watch, the field capabilities to detect spillovers in remote places before they become regional outbreaks, the organizational capacities to control outbreaks before they become pandemics, plus the laboratory tools and skills to recognize known viruses speedily, to characterize new viruses almost as fast, and to create vaccines and therapies without much delay. If we can’t predict a forthcoming influenza pandemic or any other