Spillover: Animal Infections and the Next Human Pandemic

by David Quammen

W.W. Norton, 2012

A zoonosis is an infection that can make the jump from non-human animals to humans, and as science journalist David Quammen stresses in his new book Spillover, this is a vast category. All types of influenza, Ebola, AIDS, Lyme disease, bovine tuberculosis, West Nile fever, rabies, anthrax ... each is a zoonosis. Bubonic plague is a zoonosis. It's an odd word, but Quammen believes it's a word everybody in the 21st Century will be forced to know, and he's immensely convincing. Gigantic human overpopulation, combined with poverty, hunger, massive and moving populations of refugees, and an unprecedented ease of international travel, are creating a bonanza environment for a process that's already as old as life itself:

Infectious disease is all around us. Infectious disease is a kind of natural mortar binding one creature to another, one species to another, within the elaborate biophysical edifices we call ecosystems. It's one of the basic processes that ecologists study, including also predation, competition, decomposition, and photosynthesis. Predators are relatively big beasts that eat their prey from the outside. Pathogens (disease-causing agents, such as viruses) are relatively small beasts that eat their prey from within. Although infectious disease can seem grisly and dreadful, under ordinary conditions it's every bit as natural as what lions do to wildebeests and zebras, or what owls do to mice.

Spillover is all about what happens when those conditions stop being ordinary - that is, when pathogens stop living and reproducing and evolving in their normal host-spectrum and spill over into new fields of infection, specifically in this case the human population. This is now familiar imaginative territory; it was at the heart of Steven Soderbergh's 2011 film Contagion, and the alarm at the heart of Spillover is that life might someday soon imitate art.

A man on a junket in Thailand tries an exotic dish at an out-of-the-way restaurant; the dish has not only been made from so-called 'bush meat' but sloppily made; the man is infected by a pathogen previously confined to the heart of a rain forest, and the infection ripens while he's jetting first to a stopover in Paris and then to New York City; at every step of the way, he's breathed on people, touched people, coughed or drooled on bedclothes, and otherwise failed to clean up after himself; by the time he decides, in his New York apartment one week later, that he should go to a hospital, he's infected dozens of people in dozens of time zones, each one of whom has gone on to infect dozens of others (and he himself goes on to infect many dozens more once he gets to the hospital). In the nightmare scenarios hovering over every page of Spillover, that infection is not only rampant but ferociously virulent. It's what many of the naturalists and epidemiologists Quammen interviews refer to as NBO - the Next Big One. The chances that the Next Big One will be a zoonotic migrant from some nonhuman part of the world are astronomically high.

The means of that infection are varied - pathogens can be bacteria, fungi, prions, protists, even worms. But by far the the most likely candidate is the virus, the overwhelmingly dominant organism on the planet, those fundamentally bizarre forms of semi-life only comparatively recently isolated and identified (Hans Zinsser in his great 1934 book Rats, Lice and History, which Quammen calls "a classic chronicle of medical groping and discovery," could sense very acutely the existence of something like a virus, but they proved too small for the microscopes of his day). Quammen correctly describes some of the rough parameters of these deeply weird creatures:

Expert opinion divides on the conundrum of whether viruses are alive. If they aren't, then at the very least they're mechanistic shortcuts on the principle of life itself. They parasitize. They compete. They attack, they evade. They struggle. They obey the same basic imperatives as all living creatures - to survive, to multiply, to perpetuate their lineage - and they do it using intricate strategies shaped by Darwinian natural selection. They evolve. The viruses on Earth today are well fit for what they do because only the fittest have survived.

Those fit modern-day viruses are everywhere in the world in absolutely staggering profusion (the mites that live on your eyelashes are hosts to several kinds of viruses), and although they themselves likely feel no version of emotions, it's accurate nevertheless to characterize them as eager. Viruses need other life-forms in order to be alive themselves, and they cling to living tightly, and they evolve, as it were, aggressively. When Quammen's 'spillover' holocaust - the Next Big One - strikes, it will certainly be viral.

Describing the parameters of the new world in which that will happen is the task of Spillover, and the breadth and gravity of it all make this the best and most important of all Quammen's fantastic books. It's a riveting performance, and it's brightened consistently not only by the author's signature lively writing but also by his self-deprecating sense of wonder, which never deserts him and never fails to bring a smile to the reader's face. The moment he captures during a fruit bat-trapping expedition in Bangladesh stands well for dozens of such moments throughout the book:

Hundreds of animals stirred, woke, took flight, and circled out over the river, then back around, and then out again, like flotsam adrift on a great eddy of air. They looked big as geese against the daylight sky, soaring easily on thermals or flapping in slow rhythm. When they came over us, passing low, their features were visible - the auburn fur of their bodies, the big umber wings almost translucent, the point snouts. Although they didn't like being waked, there was no sign of panic. They were magnificent. I had seen fruit bats in Asia before, but never so many in motion so close. I must have been gawking like a fool because Epstein gently advised, "Keep your mouth closed when you look up." They shed Nipah virus in their urine, he reminded me.

Despite the dark and worrying weighty matters Spillover details, despite the unanswerable warnings it sounds, there's a thin, strong joy in knowing that writers and thinkers and investigators like David Quammen are out there in the far corners of the world gawking like a fool.

He insists that his book is meant to inform and prepare rather than alarm, but nevertheless, Laurie Garrett's 1995 The Coming Plague has finally been dethroned as the thinking person's single most terrifying book.