Spillover

by David Quammen

I have eagerly gobbled up many of David Quammen’s previous works: The Song of the Dodo; Monster of God; Boilerplate Rhino; and The Flight of the Iguana. I have found them to be delightful excursions on biology and ecology. But this most recent book doesn’t live up to the high standards set by his previous works.

The topic is zoonoses: diseases that made the jump from another species to Homo Sapiens. The list of these is long, including: Ebola, the HIV virus, the SARS virus, Herpes B, Nipah, and Q Fever. Most are viruses because, as Quammen explains, viruses mutate easily and so can rapidly adjust to a new environment. And there are tons of viruses: one scientist guesses that every species on the planet has at least one custom-made virus of its very own. 

It’s certainly a well-researched work; Quammen travelled all over the world to interview people and see for himself some of the effects of outbreaks. The Ebola virus, for example, attacks gorillas and chimpanzees also, and often spills over when people eat the meat of its victims. In some areas, Ebola has wiped out all gorillas and chimps. 

His presentation on the HIV virus represents the best and the worst in the book. It’s certainly thorough: scientists have figured out that the original species jump was from a chimpanzee to a human in southeast Cameroon, along the Ngoko River, around 1908. It then travelled downriver to Brazzaville in the Congo, where it slowly, slowly increased its presence. Scientists suspect that the first big transfer out of Africa took place in the 1960s, when a large number of Haitian professionals came to the newly independent country to replace the newly-unwelcome European professionals. When they went back home, they carried HIV back with them, and it started spreading there.

But the big jump came in the early 1980s when HIV infected the gay community. The sexually active members of the community spread it quickly; one particularly odious individual who knew he had acquired a deadly contagious disease would have sex with another guy, then announce that his partner was now infected and would die, too. He seems to have infected hundreds of people. The spread of HIV was quickly throttled in the developed world, but in Africa it went on a rampage. It has now killed some 20 million people; fortunately, the rate of new infections at last seems to be declining. 

The danger of a new zoonosis appearing and spreading like wildfire is all too real. It could come from anywhere; with every species on this planet hosting at least one virus, and every one of those pathogens theoretically able to jump the species barrier and make a new home for itself in humans, the odds are not good. Even worse, the human race is now conducting an outbreak: a sudden, huge leap in numbers. In just 10,000 years we have gone from just another primate to the dominant species on the planet, and one lesson from ecology is that species outbreaks usually fall faster than they rise. As a species becomes more numerous, the possible interactions with other creatures multiply, and the high density of humans on this planet insures that any opportunistic new zoonosis will spread quickly. Eventually, some other creature, large or small, stumbles upon some way to tap the huge food resource consisting of the outbroken species, and it roars through the population even faster, wiping out huge portions of that species. 

This is an even greater threat to humans than to any other species, because our success as a species is dependent upon our cooperation. The economic interconnections among us all serve to increase our economic productivity. With seven billion people on the planet, we can afford to employ super-specialists who concentrate their efforts on extremely tiny tasks, mastering them and becoming more efficient in the process. As the population grows, we become richer. But this virtuous circle becomes vicious in the other direction. Were a pandemic to wipe out a billion people, the global economy would shrink. If we lost half our population, the remaining half would not be able to maintain the economic structure we have built, and society would grind back in developmental time. Thus, a virus that directly kills one person could indirectly kill another by depriving that person of his livelihood.

Fortunately, a goodly group of scientists are working at developing techniques for dealing with such a possibility. We now have a pretty good system in place for rapidly identifying and responding to an unknown new plague. It’s handling of the recent outbreak of Ebola seems competent, but reveals how badly underfunded they are. They can cope with small numbers of special patients, but if this outbreak gets loose in the African population, it could well become a pandemic, or what those scientists call “The Next Big One”. They have no doubt that there will be more exotic zoonoses threatening humanity, and they worry that a virus with particularly strong characteristics could overwhelm our defenses. 

Such a superbug would need only three special characteristics: 1) a slow incubation period, so that we don’t know who’s infected until it’s too late; 2) airborne contagion, so that one passenger on an airplane can infect everybody else; and 3) high mortality, so that most of those infected die. So far, we’ve been lucky: there have been pathogens with two of these three characteristics, but so far, nothing with all three has shown up. When it does — not if, when — it will wreak havoc, and our only hope will be that small group of scientists working to stay on top of all this.

So what didn’t I like about this book? It badly needs editing. This 520-page tome (with 70 more pages of footnotes) could have been edited down to 400 or even 300 pages without serious loss of content. There are just too many trivial details, niggling corrections, on-the-other-hands, and sartorial descriptions of the people Mr. Quammen meets. He threw in a long fictitious story depicting how the HIV virus might have made its way from a chimpanzee to Brazzaville. Puh-lease! I didn’t need a long tale about a traveling young man to grasp the notion that the virus spread from a remote area to a city. 

All in all, it’s a decent book, probably worth your time to read, but be brutal about skipping sections that drag. And read some of Mr. Quammen’s other books first.