Think Exotic Animals Are to Blame for the Coronavirus? Think Again.*Scientists
have fingered bats and pangolins as potential sources of the virus, but the
real blame lies elsewhere—with human assaults on the environment.*
By Sonia Shah <> February 18,
[image: fruit-bat-getty-img]
A fruit bat captured by CDC scientists Brian Amman and Jonathan Towner in
Queen Elizabeth National Park on August 25, 2018. (Photo by Bonnie Jo Mount
/ The Washington Post via Getty Images) <>

It could have been a pangolin
<>. Or
a bat
Or, as one now-debunked theory that made the rounds suggested, a snake

The race to finger the animal source of COVID-19, the coronavirus currently
ensnaring more than 150 million people in quarantines and *cordons
sanitaires* in China and elsewhere, is on. The virus’s animal origin is a
critical mystery to solve. But speculation about which wild creature
originally harbored the virus obscures a more fundamental source of our
growing vulnerability to pandemics: the accelerating pace of habitat loss.

Since 1940, hundreds of microbial pathogens have either emerged or
reemerged into new territory where they’ve never been seen before. They
include HIV, Ebola in West Africa, Zika in the Americas, and a bevy of
novel coronaviruses. The majority of them—60 percent—originate in the
bodies of animals. Some come from pets and livestock. Most of them—more
than two-thirds—originate in wildlife.

But that’s not the fault of wild animals. Although stories illustrated with
pictures of wild animals as “the source
of deadly outbreaks might suggest otherwise, wild animals are not
especially infested with deadly pathogens, poised to infect us. In fact,
most of these microbes live harmlessly in these animals’ bodies.

The problem is the way that cutting down forests and expanding towns,
cities, and industrial activities creates pathways for animal microbes to
adapt to the human body.

Habitat destruction threatens vast numbers of wild species with extinction
including the medicinal plants and animals we’ve historically depended upon
for our pharmacopeia. It also forces those wild species that hang on to
cram into smaller fragments of remaining habitat, increasing the likelihood
that they’ll come into repeated, intimate contact with the human
settlements expanding into their newly fragmented habitats. It’s this kind
of repeated, intimate contact that allows the microbes that live in their
bodies to cross over into ours, transforming benign animal microbes into
deadly human pathogens.

Consider Ebola. According to a 2017 study, Ebola outbreaks, which have been
linked to several species of bats, are more likely to occur in places in
Central and West Africa that have experienced recent episodes of
deforestation. Cutting down the bats’ forests forces them to roost in trees
in backyards and farms instead, increasing the likelihood that a human
might, say, take a bite of a piece of fruit covered in bat saliva or hunt
and slaughter a local bat, exposing herself to the microbes sheltering in
the bat’s tissues. Such encounters allow a host of viruses carried
harmlessly by bats—Ebola
Nipah <>,
and Marburg
<>, to name
a few—to slip into human populations. When such so-called “spillover”
events happen frequently enough, animal microbes can adapt to our bodies
and evolve into human pathogens.

Mosquito-borne disease outbreaks have been similarly linked to the felling
of forests
although less because of the loss of habitat than to its transformation. As
trees’ leaf litter and roots disappear, water and sediment flow more
readily along the shorn forest floor, newly open to shafts of sunlight.
Malaria-carrying mosquitoes breed in the sunlit puddles. A study in 12
countries found that mosquito species that carry human pathogens are twice
as common in deforested areas compared to intact forests.

Habitat destruction also scrambles the population sizes of different
species in ways that can increase the likelihood that a pathogen will
spread. West Nile virus, a virus of migratory birds, is one example.
Squeezed by habitat loss as well as other affronts, bird populations in
North America have declined by more than 25 percent over the past 50 years
But species don’t decline at a uniform rate. Specialist bird species, like
woodpeckers and rails, have been hit harder than generalists like robins
and crows. That increases the abundance of West Nile virus in our domestic
bird flocks because, while woodpeckers and rails are poor carriers of the
virus, robins and crows excel at it. The likelihood
<> that a
local mosquito will bite a West Nile virus–infected bird and then a human

Similarly, the expansion of suburbs into the Northeastern forest increases
the risk of tick-borne disease
<> by driving
out creatures like opossums, which help control tick populations, while
improving conditions for species like white-footed mice and deer, which
don’t. Tick-borne Lyme disease first emerged in the United States in 1975;
in the past 20 years, seven new tick-borne pathogens
have followed.

It’s not only the fact of habitat destruction that ratchets up the risk of
disease emergence, it’s also what we’re replacing wild habitat with. To
sate our species’ carnivorous appetites, we’ve razed an area around the
size of the continent of Africa
to raise animals for slaughter. Some of these animals are then delivered
through the illicit wildlife trade or sold in so-called “wet markets.”
There, wild species that would rarely if ever encounter each other in
nature are caged next to one another, allowing microbes to jump from one
species to the next, a process that begot the coronavirus that caused the
2002–03 SARS epidemic and possibly the novel coronavirus stalking us today.

But many more are reared in factory farms, where hundreds of thousands of
individuals await slaughter, packed closely together, providing microbes
lush opportunities to turn into deadly pathogens. Avian influenza viruses,
for example, which originate in the bodies of wild waterfowl, rampage in
factory farms packed with captive chickens, mutating and becoming more
virulent, a process so reliable it can be replicated in the laboratory. One
strain called H5N1, which can infect humans, kills more than half of those
infected. Containing another strain, which reached North America in 2014,
required the slaughter of tens of millions of poultry

The avalanche of excreta produced by our livestock introduces yet more
opportunities for animal microbes to spill over into human populations.
Because animal waste is far more voluminous than croplands can possibly
absorb as fertilizer, it is collected in many places in unlined cesspools
called manure lagoons. Shiga toxin–producing *Escherichia coli*, which
lives harmlessly inside the guts of over half of all cattle on American
feedlots, lurks in that waste <>. In
humans, it causes bloody diarrhea and fever and can lead to acute kidney
failure. Because cattle waste so frequently sloshes into our food and
water, 90,000 Americans are infected every year.

This process of transforming animal microbes into human pathogens is
accelerated today, but it is not new. It began with the Neolithic
revolution, when we first cleared wildlife habitat to make way for crops
and yoked wild animals into servitude. The “deadly gifts” we received from
our “animal friends,” as Jared Diamond put it, include measles and
tuberculosis, from cows; pertussis from pigs; and influenza from ducks. It
continued during the era of colonial expansion. Belgian colonists in Congo
<> built the railroads and cities
that allowed a lentivirus in local macaques to perfect its adaptations to
the human body; British colonists in Bangladesh cut down the Sundarbans
wetlands to build rice farms, exposing humans to water-borne bacteria in
the wetlands’ brackish waters.

The pandemics those colonial-era intrusions created plague us to this day.
The macaque’s lentivirus evolved into HIV. The water-borne bacteria of the
Sundarbans, now known as cholera, has caused seven pandemics so far, the
latest churning just a few hundred miles off the coast of Florida in Haiti.

The good news is that, because we are not passive victims of animal
microbes invading our bodies but fully empowered agents who turn harmless
animal microbes into pandemic-causing pathogens, there’s much we can do to
reduce the risk that these disease-causing microbes emerge at all.

We can protect wildlife habitat, so that animal microbes stay in their
bodies and don’t cross over into ours, an approach championed by the “One
movement, among others.

We can conduct active surveillance in places where animal microbes are most
likely to transform into human pathogens, hunting for ones that show signs
of adapting to the human body—and squelching them before they cause
epidemics. For the past 10 years, scientists funded by the USAID’s Predict
program did just that. While the human footprint has continued to expand
across the planet, Predict scientists have pinpointed more than 900 novel
viruses <>. around the world that
emerged as a result, including new strains of SARS-like coronaviruses

Today, the shadow of the next pandemic looms. But that’s not just because
of the novel coronavirus. The Trump administration’s liberation of
extractive industries and industrial development from environmental and
other regulatory constraints can be expected to accelerate the habitat
destruction that brings animal microbes into human bodies. At the same
time, the administration is reducing our ability to pinpoint the next
spillover microbe and to contain it when it starts to spread. The
administration decided to end the Predict program in October
Officials reportedly felt “uncomfortable funding cutting-edge science.”
Last week, the administration proposed cutting funds to the World Health
Organization too, by 53 percent

The epidemiologist Larry Brilliant once said, “Outbreaks are inevitable,
but pandemics are optional
But pandemics only remain optional if we have the will to disrupt our
politics as readily as we disrupt nature and wildlife. In the end, there is
no real mystery about the animal source of pandemics. It’s not some spiky
scaled pangolin or furry flying bat. It’s populations of warm-blooded
primates: The true animal source is us.