Spillover

I finished David Quammen’s excellent book Spillover last night.

I’m a Quammen fan. The Tangled Tree introduced me to horizontal gene transfer, an old phenomenon we’ve only begun to understand in detail, that reshaped my understanding of evolution and Darwinian theory. The Song of the Dodo explained the role of territory and range in ecology. Quammen talks to the scientists pushing our understanding forward, and lets you listen in. He goes into detail on biology and ecology, so that you understand in some depth how these systems work, without overwhelming you. And he does all of that in the middle of telling some really interesting stories.

Spillover is topical. It’s about zoonoses, or diseases that jump from animals to people. He talks specifically about the outbreaks of Ebola, MERS, SARS, HIV and others in recent history, all of which were zoonoses. Other diseases — malaria, the Black Plague, the flu — recur in discussions throughout. All of these have existed for a long time in some animal species. All infected humans in some unlucky interaction, maybe more than once, and then spread more or less well among us.

Quammen published Spillover in 2012. By then, we had learned enough about zoonoses to know that they were common, and likely to become more so as more humans intrude more deeply into animal habitat, and as our factory farms get bigger and denser.

Near the end of the book, Quammen writes:

I have asked … 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.

SARS-CoV-2, if we can’t bend the curve to lower the death toll, may well be the Next Big One described here. It’s different from its predecessor SARS-CoV in that it’s communicable for longer, including before people who have the disease show symptoms. And that has made it much more dangerous. Whether it kills tens of millions or not, its rapid global spread remind us that the viral world is large, diverse and dangerous to us. Another Next Big One is out there.

One entire section of the book describes the threat that coronaviruses pose, and the outbreak of SARS in the early 2000s. That chapter is “Dinner at the Rat Farm.” If you wanted to read just part of the book, in order to understand what’s happening today, that’s where you ought to go.

But don’t. The entire thing is excellent, and worth reading. It’s not a cheerful book, but it’s useful. We have had all sorts of opportunities in the past to learn the lessons of zoonosis. The spread of COVID-19 gives us one more chance to see the effects of a pandemic, and to think about how we protect against them in the future.

And, David Quammen, if you’re reading this: A new edition, with history and epidemiology of SARS-CoV-2, would be excellent. The global response to the outbreak has been reported in some detail. It would be great to read your thoughts on the political and popular responses to the disease, and what lessons we ought to learn.