Spillover received the right
royal thumbs-up from our get together at the end of the month. It may have been
published back in 2012, but it eerily foreshadows the 2019-20 coronavirus
pandemic that currently has the world in its grip, providing a wealth of insight
into this virulent virus and forcing us to ask questions such as ‘Why wasn’t
more done to prevent this latest outbreak?’
It is a big read – totalling a whopping
587 pages but helpfully split into 115 short chapters that make it easier, and
a pleasure, to digest.
Quammen kicks off with a pandemic that we’ve
never heard of - Hendra. First recognized in Brisbane, Australia, in 1994, it
killed a dozen horses and one man. After months of research, it was traced back
to bats. This crossing of species boundaries by infectious diseases is at the
heart of Spillover and is a phenomenon known as zoonosis.
Zoonosis leads on to the second important
concept within these thrilling pages: reservoir hosts. The reason viral
diseases such as polio and smallpox no longer plague us is that they only occur
in humans. With nowhere else to hide, they can be eradicated by sustained
vaccination campaigns. Zoonoses, in Quammen’s words, are more like guerilla fighters. They strike
unexpectedly and disappear again, sometimes for years, while living on in other
organisms where they cause little harm. Tracking down these reservoir hosts
requires intrepid individuals willing to leave the confines of their laboratory
- and Quammen indeed accompanies several on their travels.
Such as in the pursuit of Ebola, which we now
know is a horrendous virus - the bloody details of this disease have been wildly
exaggerated in the (in)famous book The
Hot Zone. But it still is a horrific disease that stalks Africa,
periodically popping up in humans but also killing countless gorillas. The hunt
for its reservoir host continues, although bats are a likely candidate.
Quammen’s vivid and personal descriptions of the fieldwork, the extraordinary
working conditions, and the chance scientific breakthroughs are what make
Spillover such a pleasant mix of popular science and reportage.
Of course, a large part of virological research
plays out in the lab, and Quammen shows himself equally at home here. The long
chapter on AIDS and HIV is a perfect example, describing the decades-long
research effort that has pushed the emergence of this disease back in time, all
the way to the start of the 20th century. At the same time, the family tree of
HIV has exploded “like an infectious starburst”, and Quammen skillfully guides
the reader down the warren of HIV-1 and HIV-2, the different groups within
these, and, nested within those, the many subtypes. Oh, and of course the
numerous variants of the closely related simian immunodeficiency virus, or SIV,
found in apes and monkeys. He relies on interviews and close reading of
publications to reconstruct the tumultuous and twisting history of scientific
breakthroughs and blind alleys.
Quammen also shines when it comes to memorable
metaphors and masterful distillation of technical details. All of this is
helped by crisp writing, short and straightforward sentences, and the repeating
of salient points. He knows the details are complicated, yet he enlightens you
in a conversational tone without ever being condescending.
A host of other, lesser-known diseases fills
these pages: herpes-B, Nipah, Marburg, bacterial zoonoses such as Lyme disease,
psittacosis, and Q-fever. We all voted for our fave viruses - one was Nipah, due to the little sweet packages that dropped from above for pigs to snuffle on.
All of these have fascinating backstories. But
one point jumped out at us in particular: bats, which are, or are at least
suspected to be, the reservoir hosts of many zoonoses. Why? Quammen highlights
some of the unique aspects of their biology that might contribute to this:
there are many species (a little-known fact is that about 20% of mammal species
are bats!), they roost and hibernate at extremely high densities, and they fly.
For more, see Bats and Viruses, Bats and Human Health, and the practical FAO
manual Investigating the Role of Bats in Emerging Zoonoses. Oh how I will never lovingly watch the flight of a bat at night.....
Viruses are everywhere: some speak of the
virosphere rather than the biosphere, while Carl Zimmer calls ours a planet of
viruses. Of the Ebola virus, Quammen writes that it “is not in your habitat.
You are in its.” And the virosphere is a Pandora’s box that we have ripped wide
open through our actions. A recurrent and important message in Spillover is how
habitat fragmentation and destruction exposes us to a menagerie of new viruses
as wild animals are forced to live and die in our midst.
Particularly fertile breeding grounds for
zoonoses are the bushmeat trade and the so-called wet markets in Asia where a
wide range of poached animals are traded and slaughtered. Nuwer’s Poached
highlighted the exotic tastes and conspicuous consumption by wealthy diners as one
of several driving forces behind the demand for wild meat. These markets were
ground zero for the SARS outbreak in 2002-03, and likely too for the current
coronavirus pandemic. There is some eerie foreshadowing here when Quammen asks:
“Will the Next Big One come out of a rainforest or a market in southern China?”
COVID-19 is only the latest in a long line of
zoonotic diseases, and will certainly not be the last. But rather than wanting
to make you more worried, Quammen wants to make you more smart. Many will have
been left bewildered by the abrupt arrival of the current coronavirus pandemic.
To better understand the world that has just gate-crashed ours, Spillover is
(still) a magnificent piece of science reporting that weds exceptional clarity
to spell-binding storytelling.
