Animal Infections and the Next Human Pandemic

By David Quammen
Spillover by David Quammen book cover
Find it on Bookshop


In Spillover, David Quammen (one of my favorite science writers) takes us through jungles, villages, and laboratories to study zoonoses: animal infections that can jump to humans. When a certain strain takes the leap and infects a human, scientists call that event “spillover”.

Quammen spends a chapter on each of nine zoonoses that caused outbreaks in humans. You will recognize at least a few: Ebola, malaria, SARS, Lyme, HIV. He digs into the stories contained in these outbreaks: how they started, the damage they did, and the scientists who studied them.

Amman’s insane jubilance was in fact just the sane, giddy thrill that a scientist feels when two small bits of hard-won data click together and yield an epiphany. Towner got it and shared it. Picture two guys in a dark stone room, wearing headlamps, high-fiving in nitrile gloves.

Main Points

The threat of eradicating zoonoses is that they hide in their “reservoir host”: an animal species that carries them. Even if we purge a particular strain of infection from humanity, there is still a constant threat that a new strain could evolve and make the jump again. There are many such diseases, which tend to hide in undisturbed ecosystems. Disturbing these areas through development or clearcutting tends to release new diseases into nearby towns and villages.

Predators are relatively big beasts that eat their prey from 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.

Some parts of the book are a little gross— a necessary evil when describing disease— but overall Quammen focuses on the science, not the drama. Reading this in 2021, the most notable takeaway is that he (with the help of the scientists he has interviewed) predicts The Next Big One to be a coronavirus. 👏

The world had a scare with the first well-known SARS-CoV strain during the 2002-2004 SARS outbreak. It was eliminated in humans, but was certainly lurking in a reservoir host. At the end of the outbreak, people celebrated, but disease scientists knew it would return. Coronaviruses can evolve quickly and are known to cause epidemics in animal populations, which makes them great candidates for a pandemic.

We are, as of this writing, still in the COVID-19 pandemic. We could be in another soon, maybe even before this one is over.

Evolution seizes opportunity, explores possibilities, and helps convert spillovers to pandemics.

Want to read more? Find Spillover here: Bookshop

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You might also like my notes on:

Fuzz: When Nature Breaks the Law by Mary Roach

The Omnivore’s Dilemma by Michael Pollan

Under a White Sky: The Nature of the Future by Elizabeth Kolbert