Sunday Times, 30 September 2012
Spillover: Animal Infections and the Next Human Pandemic
by David Quammen
The most consistent finding of modern science is that the existence of human beings is, to a rough approximation, impossible. Physics, for example,has shown that a universe containing life or even solid objects is too improbable to warrant serious consideration. Biology, meanwhile, is entirely based on an event — the appearance of replicating molecules — so implausible that only a madman would give it a moment’s thought. And yet, here we are. For the moment.
In the mid-1990s, we embraced a new reason for our nonexistence — infection. Ebola, a virus out of Africa, became the disease du jour, and a few sensational books (and Outbreak, a terrible Dustin Hoffman movie) convinced the world we were all going to melt into a bloody slurry, a phenomenon known as “bleed out”. It didn’t happen. Ebola, mysteriously, came and went in waves, killing a few hundred here and there, but never really managed to, as it were, outbreak.
As David Quammen, an award-winning American natural-history writer, explains in this tremendous book, even the bleed out was a fantasy. Most Ebola victims die, but they seldom dissolve, a source of consolation for doctors and nurses, not so much for patients. But Quammen’s big point is that it is, indeed, a miracle we are still around. We live in a world seething with infection, and fast-mutating bugs such as the H5N1 bird flu virus — one tiny genomic change in that little bastard could wipe out 20m — or, get this, a simian foamy virus that fuses cells into “gigantic, nonfunctional megacells that, under a microscope resemble huge bubbles of foam”.
So, yes, it is a wonder we are here, but even more wondrous is the fact that, since Hoffman’s dog of a film, we have stopped worrying about it. For, as Quammen repeatedly points out, we have one huge example right before our eyes of what can happen. Aids has killed around 30m and infected another 33m. We are, in fact, at risk as never before and this book, though moderate and thoughtful in tone, is even more sensational than those bleed-out operas of the 1990s.
Quammen is concerned about zoonosis, the phenomenon of infectious diseases that leap from animals to humans — H5N1 comes from birds, Ebola probably from bats via apes, and Aids most likely from chimps. In fact, there seem to be more zoonotic infections than non-zoonotic ones. These are a bigger problem now because we are a bigger problem. With a population heading rapidly towards nine billion, Quammen argues (reasonably enough) that humans, not the bacteria and viruses, are the outbreak species. Not only are we more numerous, we are more mobile.
He dramatises the implications of this in a long, half-fictional speculation about how Aids probably got out of its home in Cameroon. The important point here is that studies of the virus’s genome suggest that a bug capable of infecting humans was around as early as 1908, but it stayed in Cameroon until one human took it out, downriver through the Congo. By the 1960s it had appeared in big African cities, but it wasn’t until the 1980s that it emerged among American gays. Air travel had become commonplace. We did it for fun or business, HIV did it for survival.
Somehow, perhaps because of new antiviral treatments that successfully keep the infected alive, Aids has been normalised. The dramatic implications of its emergence have been forgotten. Yet as the population grows and people embrace air travel as a right, the risks of another such zoonotic outbreak are increasing daily. Where and when, however, are both impossible to predict.
You would be safer smoking 200 a day and drinking a case of vodka while standing in the middle of the M25 than you would swallowing bat waste product
The threat is not from bacteria — usually we can knock them out with antibiotics, though we may soon lose that ability due to mounting resistance — but from viruses. These are such weird things that we don’t know whether to classify them as animals, plants or even just objects. The great scientist Peter Medawar called them “a piece of bad news wrapped up in a protein”, which is a touch unfair as most viruses are harmless or even beneficial. A virus is a sliver of DNA whose only object in life is to replicate, which it achieves by injecting its genome into a host cell. In the case of Ebola, this sliver is terrifyingly simple; just a few boring genes can put a permanent hole in your schedule.
However simple, conquering such entities is, as Quammen brilliantly shows, fantastically complicated. Unlike the enormous number of antibiotics, effective antiviral drugs are extremely rare. Furthermore, attacking viruses from the other end — finding out where they come from and how infection spreads — is a nightmare of chemistry, biology, epidemiology and inspired speculation. We can’t even be sure of the connections in the Aids route, never mind the more exotic pathogens that we know lurk out there somewhere. Though we can say, judging by Quammen’s heroic adventures in caves and jungles, bats always seem to be in there somewhere. This being the case, perhaps the wisest and most practical piece of advice in this book is “keep your mouth closed when you look up”. You would be safer smoking 200 a day and drinking a case of vodka while standing in the middle of the M25 than you would swallowing bat waste products.
This is, as I said, a tremendous book. Its one flaw is that it is too long, because Quammen suffers from that American habit of overloading his narrative with an excess of repetitive and over-detailed reportage. Certainly he has much to report — his research efforts are admirable — but too much is too much.
Otherwise, this gives you all you need to know and all you should know. Quammen’s research and the analysis make sensationalism unnecessary. It is potentially as bad as it could be, even without bleed outs. We are indeed a species that has broken out of its natural niche and provided viruses with juicy new replication routes. Having been born of the mysterious coincidences of physics and the rank outsiders of biology, our next hurdle seems to be the as yet indecipherable logic of zoonotic epidemiology. So the next time you look up at the stars in wonder at our strange destiny, close your mouth.