Shortly after one of us (Jared Diamond) boarded a flight from Hong Kong back to Los Angeles, the passenger in the next seat sneezed. She sneezed again—and again—and then she began coughing. Finally she gagged, pulled out the vomit bag from the seat back in front of her, threw up into the bag, stood up, squeezed past, and lurched to the toilet at the front of the plane. The woman was obviously miserable, but sympathy for her pain was not what I felt. Instead I was frightened and asked the flight attendant to move me to a seat as far from her as possible.
All I could think of was another sick person, a man from Guangdong province in southern China, who spent the night of February 21, 2003, at the Metropole Hotel in Hong Kong, an upscale establishment with a swimming pool, fitness center, restaurants, a bar, and all kinds of areas where visitors could socialize and connect. The man stayed a single night in room 911. Unfortunately for him and for many other people, he had picked up severe acute respiratory syndrome, or SARS—perhaps directly from an infected bat or from a small, arboreal mammal called a civet, common in one of Guangdong’s famous “wet markets” that sell wild animals for food, or else from a person or chain of people ultimately infected from one of those animal sources.
In the course of his brief stay, the man initiated a SARS “super spreader” event that led to at least 16 more SARS cases among the hotel’s guests and visitors and then to hundreds of other cases throughout Asia, Europe, and North America as those guests and visitors continued on their travels—just as my neighbor was now traveling to L.A. The infectiousness of room 911’s guest can be gauged from the fact that three months later, the carpet right outside the door and near the hotel elevator yielded genetic evidence of the SARS virus, presumably spewed out in his own sneezing, coughing, or vomiting.
I didn’t end up with SARS, but my experience drives home the terrifying prospect of a novel, unstoppable infectious disease. Globalization, changing climate, and the threat of drug resistance have conspired to set the stage for that perfect microbial storm: a situation in which an emerging pathogen—another HIV or smallpox, perhaps—might burst on the scene and kill millions before we can respond.
Pathogen ParadoxTo grasp the risk, we first must understand why any microbe would evolve to sicken or kill us. In evolutionary terms, how does destroying its host help a microbe to survive?
