Spillover: Animal Infections and the Next Human Pandemic

by David Quammen

Why are zoonotic diseases important? I’ve been asked that question, and have asked it of others, more than a few times during my six years of chasing the subject. (One fellow, a respected historian I met at a conference, suggested that I forget about Ebola and write a book on asthma, which afflicts 22 million Americans. He happened to be asthmatic.) Given the global scorecard of morbidity and mortality caused by old-fashioned infectious diseases—such as cholera, typhoid, TB, rotavirus diarrhea, malaria (excepting Plasmodium knowlesi), not to mention chronic illnesses such as cancer and heart disease—why divert attention to these boutique infections, these anomalies, that spill out of bats or monkeys or who knows where to claim a few dozen or a few hundred people now and then? Why? Isn’t it misguided to summon concern over a few scientifically intriguing diseases, some of them new but of relatively small impact, while boring old diseases continue to punish humanity? After my detour through the Cholera Hospital, after being pinioned by that mother’s expectant stare, I found myself asking the same thing: Why obsess about zoonoses? In the larger balance of miseries, what makes anyone think they should be taken so seriously? It’s a fair question but there are good answers. Some of those answers are intricate and speculative. Some are subjective. Others are objective and blunt. The bluntest is this: AIDS.