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Every day, new evidence emerges of the havoc that COVID-19, the disease caused by the coronavirus, is wreaking all around a thoroughly globalized world. As a new pathogen sweeps nations and continents, people are being quarantined in hospitals and aboard ships in distant ports, and the movement of labor and vital supplies has been profoundly disrupted. What’s becoming clear—from China to Iran to Italy to the United States—is that the new pathogen isn’t the only thing putting human life at risk. The shortages and other disruptions that an epidemic causes, not to mention the social inequities that it aggravates, massively amplify the consequences caused by the disease itself.

And yet these dynamics—far from being unique to the current epidemic—have recurred time and again for at least half a millennium. As a historian of slavery and medicine, I often come across bleak accounts of smallpox outbreaks that happened 200 to 500 years ago. Then as now, the poorest and least powerful people were usually at the greatest risk of infection—and the public-health measures of the time either neglected these people or actively harmed them. This treatment frequently enabled otherwise containable disease outbreaks to spread.

In my historical research, I study the period from 1500 to 1800, a three-century span during which millions of people endured warfare, displacement, confinement, labor exploitation, insufficient access to medical treatment, and unsanitary living conditions. This period was also defined by then-unprecedented levels of regional and global travel, trade, conflict, and forced and voluntary migrations.

During the period I study, everyone’s well-being was at some risk in some way during a smallpox epidemic, regardless of whether a person was the colonist or the colonized, the enslaver or the enslaved, rich or poor, or of African, Native American, or European descent. The first recorded smallpox outbreak in the Americas struck the Caribbean roughly 500 years ago; a European man arrived on the Caribbean island of Hispaniola carrying the disease in 1518. This outbreak ultimately killed thousands of free and bound Taíno people who performed agricultural and mining labor on the island. Many Native Americans were particularly vulnerable during smallpox outbreaks because they had not previously been exposed to the disease and were therefore not immune.

Only people who developed smallpox immunity after contracting the disease, naturally or by inoculation, were safe from Variola virus. But smallpox epidemics still imperiled those who survived and gained immunity. After epidemics passed, survivors grieved deserted towns whose inhabitants had either died or fled in panic. Descriptions of deceased and ailing enslaved or bound African, Native, and European laborers punctuate early modern correspondence about famines that ensued after agricultural labor became untenable. Goods weren’t the only thing in short supply. Clergymen, slaveholders, and colonial officials lamented the suspension of normal religious, social, and political gatherings.

Contagious diseases spread and kill when humans create the social and material conditions for them to do so, and they harm entire societies, often in unpredictable ways.

One might be tempted to believe that human conditions have radically improved since the early modern period, yet the new coronavirus is arriving in societies ripe for contagion. It is now spreading in states where tens of thousands of people are without permanent shelter or sanitary living conditions and rely on food banks for survival. COVID-19 is also spreading in states with large populations of incarcerated people, where inmates and detainees live in crowded conditions and lack adequate health care, food, and hygiene. Many of the states listed in the Centers for Disease Control and Prevention’s latest situation report have key international ports, transit hubs, and manufacturing and agricultural centers—locations whose importance to global trade and distribution networks frequently does not translate into adequate pay or health insurance for the people who work in them. Farm, factory, and transit workers in many states are notoriously underpaid and underinsured, if insured at all, and may have to perform “super” commutes on public transit daily. These conditions are perfect for novel viruses to spread and disrupt trade and distribution networks, supply chains, and daily life within and beyond the borders of any one country.

The historian Paul Kelton has documented how European colonists’ actions often abetted the spread of smallpox epidemics and impeded Native people’s access to food, shelter, and medicine. In a sobering account of the 1519 outbreak, the Dominican friar Bartolomé de las Casas explained that the lack of adequate food and shelter, taxing labor, and “little or no care for their health and conservation” on the part of the Spanish caused the Taíno to perish rapidly. Spanish and indigenous maritime networks spread the disease in the Caribbean and the North and South American mainland, where thousands more perished, and overwhelming indigenous healers in the region. When access to food, medicine, shelter, and treatment excluded any subset of the population, smallpox typically continued to spread and the comorbid consequences were catastrophic.

As the epidemic persisted, Roman Catholic friars in the Caribbean recorded that the decimated labor force could no longer support the brutal mining and burgeoning sugar industries. Injustice led to more injustice, as the friars requested recompense from the Spanish Crown in the form of enslaved Africans. The Crown obliged. In the decades that followed, Europeans, Africans, and Native Americans became acutely aware of the harrowing conditions aboard slave ships that enabled smallpox to spread among enslaved Africans and to those living in and around colonial settlements.

In the 1600s, European colonists began to enforce maritime quarantines for slave ships arriving from Africa. If enslaved Africans appeared to be ill with smallpox or other contagious diseases, colonial officials sent them to the Isla de Cabras in Puerto Rico, Sullivan’s Island in South Carolina, Tybee Creek in Georgia, the Goat Pens in Jamaica, the Îles du Salut in French Guiana, the Isla de Aves in Venezuela, and countless other islets, coves, estuaries, and coastal locations. Slave traders would either disembark the enslaved or keep them aboard the ship for anywhere from two weeks to a few months, until the contagious disease ran its course. While many enslaved Africans who were quarantined for smallpox survived that virus, their lengthy quarantines aboard ships and on remote islands enabled comorbid infections, parasites, and dysentery to spread. These consequences reveal just how exclusionary “public” health policies can be.

Because of European colonists’ public-health practices, smallpox became associated with the slave trade, and enslaved Africans were treated as the sole or primary source of all smallpox outbreaks. At times, the narrow focus on the slave trade blinded early Americans to other vectors. As the historian Peter McCandless has explained, the British were caught off guard when smallpox spread from the Catawba Nation, whose members lived inland in the Carolinas, to Charleston in 1759. British troops reputedly carried the disease from the interior to the port city after a campaign against the Cherokee. The outbreak severely disrupted the South Carolinian economy, as panic spread, businesses closed, and people fled. The public-health needs of the colony overwhelmed local physicians, who struggled to inoculate and treat the thousands of free and enslaved people who needed care. Though humanity’s medical and public-health practices have advanced significantly since the 1700s, our deeply imperfect sense of disease geographies continues to inform how and when we prepare for public-health threats.

Over the past two months, the public has been inundated with images that map the coronavirus onto geopolitical borders. These images simplify dense information in ways that create the illusion that contagious diseases are linked to particular peoples and places. These maps also reinforce the illusion that international and domestic borders are somehow impermeable, and deemphasize the travel, trade, conflict, and migration routes by which epidemics can spread or along which supply chains might be disrupted. In her book Pox Americana, an account of the smallpox epidemic that spread throughout North America during the Revolutionary War, the historian Elizabeth Fenn demonstrates just how far conflict, trade, and travel can spread a disease.

Today, people in the United States are seeing how quickly the coronavirus can spread and precipitate supply shortages. In the past week alone, Americans have seen hand sanitizer, rubbing alcohol, and surgical masks fly off the shelves at local drugstores. Pervasive anxieties about COVID-19 and necessary public-health precautions within and beyond our borders have already disrupted international and domestic trade and slowed or stopped the manufacture of certain pharmaceutical ingredients. Likewise, the demand for protective medical equipment and technologies has overwhelmed global markets, making it more difficult for medical providers to get the materials they need to do their lifesaving work.

Disruptions to distribution networks and labor forces can be just as hazardous as supply shortages. For example, in the 1680s, an epidemic variously described as smallpox, measles, chicken pox, or some combination of the three afflicted San Juan, Puerto Rico. Enslaved people faced the highest mortality rates, but clergy, free people of color, Spanish colonists, and troops perished in high numbers as well. One bishop collected medicines and formed an apothecary to distribute them to those in need. The bishop enjoyed some success. However, he later recounted the deaths of clergymen, who were unable to provide sacraments to the dead, and chastised secular authorities for failing to slaughter cattle and distribute supplies—a failure of planning that helped precipitate a famine. This story reminds us how crucial, careful coordination; inclusive public-health practices; and the preservation of the health of laborers can mitigate the consequences of epidemics.

Epidemics always test the limits of our societies and political imaginations, but history holds some unmistakable lessons: Societies further their own destruction whenever they fail to provide anyone health care, housing, or dispensation from work because of their employment, socioeconomic, or immigration status. The world we live in today is radically different from the early modern world that I study—but in some ways it’s very similar. Epidemics continue to remind us of our shared humanity because they show us how our individual survival is bound up in one another’s well-being.

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