spilloverSpillover: Animal Infections and the Next Human Pandemic

  • Author:  David Quammen
  • Published:  2012
  • Publisher:  W. W. Norton & Company
  • Pages:  587
  • First Line:  “The virus now known as Hendra wasn’t the first of the scary new bugs.”
  • Last Line:  “It all depends.”
  • Awards:  Shortlisted for PEN/E. O. Wilson Literary Science Writing Award  /  finalist for Andrew Carnegie Medal for Excellence in Nonfiction
  • First Read:  Fall 2012

I get a lot of books out of the library, in the same way that I used to read new books at various stores back when I worked at bookstores.  I rarely, however, read those books more than once.  That’s why I buy books: so I can read them again and again.  But every now and then there is a book I go back to and I pull out of the library again.  Such a book is Spillover: Animal Infections and the Next Human Pandemic, which I first grabbed off the shelf when it was a brand new book and I was working at the Booksmith and which I just dived into for a second time because it keeps pulling at my brain.  There’s a reason for that.  It’s not only a really well-written book, one that tells a good scientific story, a fascinating human story and does it all very well.  It’s also because I have an interest in viruses.

Actually, I have a fascination for viruses.  I have no interest in ever studying science, but this is the kind of science that does call to me.  I’m not a Hot Zone kid (the book discusses how the highly successful book The Hot Zone by Richard Preston got a lot of people interested in viruses) and in fact I didn’t read Preston’s book until after I read this one.  No, if there are a couple of source materials that drew my interest this way it was The Stand, the magnificent haunting story by Stephen King in which the army manages to create a virus that wipes out most of the world, and And the Band Played On, Randy Shilts’ magnificent work of journalism that really cemented my interest in AIDS (there are a couple of flaws in the Shilts book that Quammen addresses but one of those was pushed on Shilts by his editor and the other one was something that wasn’t discovered until after Shilts had died and he couldn’t have known and neither one really affect the way Shilts tells the human story in his book).

Quammen focuses on zoonotic viruses, those viruses that can pass between animals and humans and are, therefore, almost impossible to wipe out.  Think of the great strides the world has made to eradicate smallpox and polio.  That’s because those viruses don’t spill over.  They are restricted to humans.  Therefore they can be eradicated.  But then think of something like Ebola.  It’s pretty much impossible to eradicate Ebola completely because it lives in animals (most likely bats) and then, through circumstances, is passed to humans.  The only way to eliminate it completely is to eliminate the host animal and that’s pretty much impossible without nuking the entire continent of Africa.

But it’s not just the scientific information that Quammen provides, like, say, the way he explains how SARS first probably passed to humans and how it came to be so deadly in such a short time and precisely why it didn’t become even more deadly.  It’s also how he tells the story, sometimes with a little bit of humor, such as this passage:  “Also that year, 1996, Reston virus reentered the United States by way of another shipment of Philippine macaques.  Sent from the same export house near Manila that had shipped the original sick monkeys to Reston, Virginia, these went to a commercial quarantine facility in Alice, Texas, near Corpus Christi.  One animal died and, after it tested positive for Reston virus, forty-nine others housed in the same room were euthanized as a precaution.  (Most of those, tested posthumously, were negative.)  Ten employees who had helped unload and handle the monkeys were also screened for infection, and they also tested negative, but none of them were euthanized.”  (p 81)  That kind of humor, in a book that has a lot of bleak information about what might be the next big disease and how potentially dangerous it could be, provides for some fun and fascinating reading.  And he manages to do it throughout the book.

Think about this: do you know what the deadliest virus on the planet is?  By that, I don’t mean the virus that has killed the most people (probably still the Spanish Influenza that ravaged the world after World War I, though AIDS is coming close), but the one that has the highest chance of killing you?  It’s rabies.  If you get it and you aren’t vaccinated before you start to show signs, you will die.  That’s not hyperbole.  Ebola kills 50% of the people who get it.  Marburg can kill up to 90%.  Rabies kills everyone who gets it.  Until 2004 there was not a single documented case of a rabies survivor who hadn’t been vaccinated before the onset of symptoms and today there are only five, all done through the same procedure (which has only had a 20% success rate).  But Quammen manages to discuss rabies, how it survives and what that means for the way a virus works.  He helps us understand viruses and how they manage to survive even when they kill the host 100% of the time and he even manages to add in a little humor.

Where’s the balance point in that dynamic interplay between transmission and virulence?  It differs from case to case.  A virus can succeed nicely in the long term, despite killing every individual infected, if it manages to get itself passed onward to new individuals before the death of the old.  Rabies does that by traveling to the brain of an infected animal – commonly a dog, a fox, a skunk or some other mammalian carnivore, with flesh-biting habits and sharp teeth – and triggering aggressive changes of behavior.  Those changes induce the mad animal to go on a biting spree.  In the meantime, the virus has traveled to the salivary glands as well as the brain, and therefore achieves transmission into the bitten victims, even though the original host eventually dies or is killed with an old rifle by Atticus Finch.  (p 296)

A large part of the book comes down to one animal: bats.  That’s because bats are the Australia of the animal kingdom: they are going to kill you.  It might be subtle, but then again, Australia can be more subtle in the ways it kills you as well (a Prime Minister once went swimming and was never seen again – another potential future Great Read is Bill Bryson’s In a Sunburned Country).

But a large fraction of all the scary new viruses I’ve mentioned so far, as well as others I haven’t mentioned, come jumping at us from bats.  Hendra: from bats.  Marburg: from bats.  SARS-CoV: from bats.  Rabies, when it jumps into people, comes usually from domestic dogs – because mad dogs get more opportunities than mad wildlife to sink their teeth into humans – but bats are among its chief reservoirs.  Duvenhage, a rabies cousin, jumps to humans from bats.  Kyasanur Forest virus is vectored by ticks, which carry it to people from several kinds of wildlife, including bats.  Ebola, very possibly; from bats.  Menangale: from bats.  Tioman: from bats.  Melaka: from bats.  Australian bat lyssavirus, it may not surprise you to learn, has its reservoir in Australian bats.  And though the list already is long, a little bit menacing, and in need of calm explanation, it wouldn’t be complete without adding Nipah, one of the more dramatic RNA viruses to emerge within recent decades, which leaps into pigs and via them into humans: from bats.  (p 313-314)

Does that last disease sound familiar, coming from bats, via pigs, into humans?  Maybe you saw Contagion, that first-rate film that was my under-appreciated film of 2011.  That’s how the fictional disease in that film, based in part on Nipah, spills over into humans and when we discover that, at the end of the film, it’s an amazingly effective and chilling scene.

This book might not be for everyone.  You might not be up for reading about Ebola while eating dinner like I am.  You might not be interested in viruses at all.  But, as a science book, it is compulsively readable and I can imagine I’ll go back to it again someday.  The world can be a scary place sometimes.  But science has knowledge for us.  It matters and it helps to know it.

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