The Invisible Killers
Humankind has made so much progress in bending
nature to our will that we sometimes forget our own place in it. The history of
pandemics shows that the proverbial fourth horseman of the apocalypse –
pestilence – can never be vanquished, only contained.
- Frank
M. Snowden, Epidemics
and Society: From the Black Death to the Present, Yale University Press, 2019.
Mark Honigsbaum, The Pandemic Century: One Hundred Years of Panic, Hysteria, and Hubris, Hurst Publishers, 2019.
MILAN – In 1969, the US surgeon general,
William H. Stewart, told Congress that it was time “to close the books on
infectious diseases” and “declare the war against pestilence won.” Antibiotics,
vaccines, and widespread advances in sanitation were making the world healthier
than ever. Within a few years, the medical schools at Harvard and Yale actually
closed their infectious-disease departments. By then, polio, typhoid, cholera,
and even measles had essentially been eradicated, at least in the West.
But triumphalism was not only premature; it was
dangerously foolhardy. The HIV/AIDS epidemic broke out in the United States
just a decade later, and never has been vanquished. Then, following a short
lull in the 1990s, came SARS, MERS, Ebola, Zika, and avian and swine flu, to
name just a few of the outbreaks so far this century. Though most of these new
diseases have primarily afflicted the poorest parts of the world, they should
have made clear that the war on microbes was far from over.
Nonetheless, a sense of invulnerability has
prevailed in the West. It was assumed that even if epidemics had not been
consigned to history, they posed a risk only to geographically and economically
distant societies. The novel coronavirus that emerged in Wuhan, China in
December has shattered this illusion, showing once again that novel pathogens
are equal-opportunity killers.
After initially deceiving ourselves that
COVID-19 would remain just another Asian health crisis, the entire world is now
grappling with a runaway pandemic. Suddenly, public-health authorities
everywhere are trying to flatten the contagion curve with quarantines, travel
bans, and unprecedented society-wide lockdowns, while governments and central
banks try desperately to flatten the recession curve with unprecedented
stimulus packages.
DISEASE AND DENIAL
One lesson is already clear: Even in the
richest, most advanced economies, humans are still humans, which means they are
vulnerable to new microbial threats, particularly zoonotic infections (diseases
that spread from non-human animals) resulting from natural evolution and
facilitated by human activities. As two recent histories of pandemics show, it
is always only a matter of time before a virus, bacterium, or parasitic
organism makes the leap from some non-human species to our own.
Ebola, for example, came from chimpanzees, just
as bubonic plague emerged from rats and COVID-19 (most likely) from bats. And,
in addition to worrying about new microbes, we also must worry about older
ones. Owing to antigenic mutations, malaria and tuberculosis, once almost
defeated, have reemerged in drug-resistant forms.
In Epidemics and Society, the
Yale University historian Frank M. Snowden shows why the West’s
complacency was never justified. Far from being the exclusive preserve of
“backward” societies, deadly disease outbreaks are, if anything, a negative
byproduct of human progress. By altering ecosystems and erasing natural
frontiers, humans have continuously exposed themselves to germs, viruses, and
bacteria that evolve to exploit their vulnerabilities. The push of economic
development has brought more opportunities for humans and animals to intermingle,
and globe-spanning trade has established new routes for the propagation of
disease.
In recorded history, the battle between humans
and microbes has essentially been a fight between reason and superstition. For
centuries, human societies felt powerless in the face of pandemics, so they
resorted to religious rituals to placate some supposedly irate god. When
science eventually triumphed over religion, one illusion was replaced by
another. We convinced ourselves that we were the gods, capable of conquering
nature and the microbial world.
By examining this long and painful learning
process, we can better understand why the world was so
unprepared for the current crisis. Snowden confidently takes the reader on a
wide-ranging journey, tracing the history of the major pandemics that have
afflicted the world – from bubonic plague, smallpox, and cholera to
tuberculosis, malaria, polio, HIV, and Ebola. Snowden’s goal is to show how
humanity learned to tame infectious diseases through the creation of public-health
systems and the progress and dissemination of medical knowledge.
This has been a constant struggle, in part
because each infectious disease has been unique. For some, the key trait was
their contagiousness; for others, it was their deadliness. Some were bacterial,
others viral or parasitic. Some were transmitted by air, others through
contaminated water or vectors like fleas, mosquitoes, and lice.
What they all shared was the ability to inflict
severe suffering on humans and cause far-reaching disruption of entire
societies. Infectious diseases have a unique capacity to fuel anxiety, fear,
mass hysteria, and outbursts of religiosity (especially in the past). They pose
a direct challenge to social cohesion and solidarity, and thus to a society’s ability
to manage collective crises.2
PEAK PANDEMIC
Of all the landmark infectious outbreaks that
Snowden analyzes, the bubonic plague remains the most emblematic for its
epidemiology, persistence, and effects on society. Even more to the point, it
permanently influenced how health authorities deal with infectious diseases.
Remembered for its virulence, lethality, and
horrifying clinical manifestations, the plague killed 50% of those infected
within days of the onset of symptoms. And, unlike polio, measles, mumps, and
other diseases that tend to strike children and the elderly, the plague
targeted adults in the prime of life, leaving behind many widows and orphans –
and thus magnifying the economic, demographic, and social dislocations.
Moreover, the plague is the only highly
infectious disease that has continuously ravaged the world throughout the last
1,500 years, accompanying humanity from the age of religious superstition into
the age of scientific hubris. It usually emanated from Africa or Asia and then spread
to Europe and America with the help of globetrotting merchants. Recurring
epidemic waves lasted for decades or even centuries.
The Black Death, for example, wiped out up to
one-third of the European population between 1334 and 1372, and then returned
intermittently until as recently as 1879. Meanwhile, the other infectious
diseases that emerged during this period – from syphilis in the 1490s to
cholera in 1830 – ran in parallel with it.
For centuries, Europeans believed that the
plague was sent by an angry deity as punishment for disobedience and sin. To
placate divine wrath, communities often sought to scapegoat and cast out the
supposed sinners, be they prostitutes, Jews, religious dissenters, foreigners,
lepers, beggars, or accused witches.
During the plague years of the fourteenth and
fifteenth centuries, towns across Europe closed themselves off to outsiders and
hunted down anyone within their walls who was deemed undesirable. Those who
were apprehended were stoned, lynched, and burned at the stake.
A less cruel response focused on propitiating
the angry god through penitence. A typical example was the outdoor procession
to a holy shrine amid rogations and confessions, like those organized by the
Flagellants who traveled across Europe before being persecuted by the
Inquisition.
In other cases, afflicted communities resorted
to the cult of saints who were supposed to intercede with God on behalf of
suffering humankind. In recognition of Mary’s intervention to end the plague in
1631, for example, the city of Venice built the monumental church of Saint Mary
of Health at the entrance to the Grand Canal.
Religious fanaticism clearly was not enough to
defeat the plague, given its continuous recurrence. But other anti-plague
measures, many of them draconian, represented some of the first
institutionalized forms of public-health policy.
During the Black Death, Italian cities pioneered
plague regulations that cloaked health authorities with emergency powers and
facilitated coordination between the army and the bureaucratic apparatus.
Within cities, the ill were isolated in pest-houses or locked in their homes
with guards at the doorstep. The military was delegated to isolate the
population with sanitary cordons to prevent the inflow of disease-carrying
people and goods. Venice was the first city to quarantine ships and their
crews.
In the event, these early anti-plague
policies marked a key moment in the emergence of the modern state. Deadly
outbreaks justified top-down measures to control the economy and the population
through forcible detention, surveillance, and the suspension of liberties. The
same containment and social-distancing measures would remain the first line of
defense against almost any infectious disease, from cholera and yellow fever to
HIV and Ebola. And though these policies were not always appropriate or
effective, they conferred an image of decisive leadership on rulers.
SCIENTIFIC HUBRIS
Despite the prevailing superstitions, our
ancestors understood that the plague was transmitted from person to person, and
that isolation was necessary to contain the contagion. Still, they did not know
what caused the disease. For centuries, doctors, influenced by the so-called
miasma theory, believed that “bad air” emanating from rotting organic matter
was the source of sickness.
Only in the eighteenth and nineteenth centuries
did physicians begin to understand what was really happening beneath the
surface. The invention of the microscope led to the germ theory of disease,
which identified microorganisms – not miasma – as the source of infection. In
the case of the plague, the culprit was the bacterium Yersinia pestis,
which was carried by fleas living on the black rats that were a constant
presence in the crowded cities and merchant ships of the time.
The emergence and widespread acceptance of germ
theory represented a turning point in the fight against infectious disease,
ushering in a medical revolution and the creation of entire new fields such as
microbiology, immunology, parasitology, and tropical medicine. By the
mid-twentieth century, the most prevalent and aggressive infections were in
retreat, thanks to the discovery of vaccines and antibiotics, higher living
standards, and improved hygiene.
Vaccination alone reduced the incidence of
smallpox, diphtheria, tetanus, rubella, measles, mumps, and polio to such a
radical degree that these diseases have been largely forgotten. The chemical
DDT was poised to eradicate malaria and other insect-borne pathogens until it
was found to be carcinogenic. And cholera was more or less knocked out by sand
filtration and the chlorination of water.
In The Pandemic Century, a
vivid account of the scientific community’s fight against viruses over the last
century, the science journalist Mark Honigsbaum shows how these achievements
produced a sense of mastery over the microbial world. After centuries of
suffering at the hands of capricious gods, humanity suddenly began to develop
seemingly divine powers of its own.
But with that realization came hubris. In 1948,
US Secretary of State George Marshall confidently declared that humanity was
about to eradicate infectious diseases from the Earth. To his generation,
microbes were seen as static or slowly evolving, geographically constrained,
and thus eminently manageable. Old diseases were being wiped out, and few
stopped to consider that new ones might arise.
As is obvious to us now, this idea of microbial
fixity – that there can be only so many diseases – was misplaced. Since 1940,
scientists have identified 335 new infectious diseases, two-thirds of which
originate in wildlife, particularly bats. Familiar examples include Lassa
fever, Marburg virus, Lyme disease, Rift Valley fever, West Nile virus, SARS,
MERS, Nipah virus, and Ebola, but there are many, many more.
Whenever dangerous pathogens are defeated, it
is only a matter of time before others take their place. New diseases are the
inevitable condition of living in a dynamic world. Human beings are part of an
immensely complex ecological system. Bacterial and viral infections can lie
dormant in tissue and cells – or under now-melting
permafrost –
for decades before being reactivated by a sudden shock to the system, or
through co-infection with another microbe.
In 2013, for example, Simon Anthony of Columbia University and his
team discovered that the number of novel viruses in all mammalian species could
be around 320,000, with bats being the most common carriers because they live
in large communities, travel long distances, and are widespread throughout the
world. The line that divides infectious from chronic diseases is also
increasingly blurred. Papillomavirus, for instance, is the primary cause of a
number of cancers affecting both men and women.
Moreover, according to a 2016 report by the US National Academy of
Medicine, “the underlying rate of emergence of infectious diseases appears to
be increasing.” Many more diseases are emerging from animal reservoirs and
ecological niches that used to be far removed from human populations.
Demographic growth, climate change, crowded cities, persistent poverty, and
global trading routes continue to disrupt fragile ecological equilibriums and
expose humanity to the threat of new killer pathogens.
PROCEED WITH CAUTION
In Epidemics and Society, Snowden
points to a 1998 report from the US Department of Defense warning that,
“Historians in the next millennium may find that the twentieth century’s
greatest fallacy was the belief that infectious diseases were nearing
elimination. The resultant complacency has actually increased the threat.” Just
two decades later, that prediction has been borne out, with rich and poor
countries alike brought to their knees by a coronavirus pandemic.
That said, it is not the scientific community
that bears all of the blame for our miscalculations. After the exuberance of
the 1960s and 1970s proved untenable, virologists, epidemiologists,
international organizations, and non-governmental organizations have understood
that pandemics are still an acute threat. In 2015, the philanthropist Bill Gates sounded the alarm about the world’s lack of
preparedness for a flu pandemic. But policymakers and business leaders were too
busy reaping the fruits of unfettered globalization to heed the warnings.
To be sure, no other recent epidemic has
threatened global health and the economy on the scale that COVID-19 has. The
World Health Organization did warn in 2009 that the swine flu (H1N1) met the
criteria for a pandemic virus. But the risk of global disruption
did not materialize. Similarly, in 2003, SARS was expected to become a new
influenza pandemic, but that turned out to be a false alarm. While a single
sneeze can set a pandemic in motion, the intra-species contingencies are
complex, making large-scale pandemics low-probability events.
But low-probability does not mean no
probability. The COVID-19 pandemic has exposed our vulnerability and lack of
preparedness, underscoring the need for a more cautious approach in the future.
As with all infectious outbreaks, its suddenness has sown confusion and chaos.
The psychological, economic, and social damage it has inflicted will lead to
permanent changes in our economies, politics, and individual lives.
New pestilences will emerge without warning in
the future. But one hopes we will prepare for them without adopting an
apocalyptic mindset or indulging in the scapegoating of the Middle Ages. Living
under perpetual pandemic alert would strain our livelihoods and limit our
freedoms. And besides, there is a third way. Hubris should defer to humility.
Our scientific aspiration should be to understand the microbial world, not to
conquer it.
Governments, for their part, should heed the
insights that science offers. By adopting more sustainable economic paradigms,
strengthening public-health systems, restoring faith in experts, and developing
resilience against negative shocks, we can minimize the likelihood of another
pandemic-driven global catastrophe.
No matter how deep our understanding of the
microbial world, Snowden and Honigsbaum remind us, nature will always furnish
viruses, bacteria, and parasites with endowments we didn’t anticipate. After
the COVID-19 pandemic has passed, theirs and other books on infectious diseases
are likely to remain open for quite some time.
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Writing for PS since 2010
25 Commentaries
25 Commentaries
Edoardo Campanella is a fellow at the Center
for the Governance of Change at IE University in Madrid and co-author
(with Marta Dassù) of Anglo Nostalgia: The Politics of
Emotion in a Fractured West.
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