Then, as in 2020, outsiders and marginalized groups were blamed for spreading the illness. “By means of Irish vagrants from Sunderland, the cholera has been twice brought among us,” read one English account.

Then, as in 2020, the poor were vastly more likely to die. In nineteenth-century Hamburg, the poorest people were nineteen times more likely to die of cholera than the richest people. This statistic has only worsened: In the twenty-first century, poor people are thousands of times more likely to die of cholera than rich people. Cholera kills at least ninety thousand people every year, even though there is a safe and effective vaccine and the disease is almost always survivable with proper fluid replenishment. Cholera continues to spread and kill not because we lack the tools to understand or treat the disease as we did two hundred years ago, but because each day, as a human community, we decide not to prioritize the health of people living in poverty. Like tuberculosis,* malaria, and many other infectious diseases, cholera is only successful in the twenty-first century because the rich world doesn’t feel threatened by it. As Tina Rosenberg has written, “Probably the worst thing that ever happened to malaria in poor nations was its eradication in rich ones.”

Disease only treats humans equally when our social orders treat humans equally. That, too, is precedented. After plague, caused by the bacterium Yersinia pestis, swept through England in the fourteenth century, one chronicler noted, “Virtually none of the lords and great men died in this pestilence.”

In that pestilence, perhaps half of all humans living in Europe died between the years of 1347 and 1351. What was then usually called “the pestilence” or “the mortality” is now known as the Black Death, and this torrent of plague also devastated Asia, North Africa, and the Middle East. As the Egyptian historian al-Maqrizi noted, the plague “did not distinguish between one region and another.”

Al-Maqrizi’s hometown of Cairo was the world’s largest city outside of China in 1340, with a population of around six hundred thousand. But at least a third of Cairo’s residents died in an eight-month period beginning in the summer of 1348. The famous world traveler Ibn Battuta reported that at the height of the pestilence in the city of Damascus, 2,400 people died every day.

To many, it felt like the end of humanity had arrived. The historian Ibn Khaldūn wrote that it felt “as if the voice of existence in the world had called out for oblivion.” In Christian communities, the devastation was seen as more final and total than even the Great Flood. The chroniclers of Padua wrote that at least “in the days of Noah, God did not destroy all living souls and it was possible for the human race to recover.”

It’s hard even to fathom the scope of the loss. Cities from Paris to London to Hamburg saw most of their residents die from the plague and resulting systemic collapses. In Dubrovnik, the death was so unrelenting that the government ordered every citizen to fill out a will. In Florence, a city of more than one hundred thousand people, one recent estimate concluded that about 80 percent of the city’s population died in a four-month period. In Ireland, a Franciscan friar named John Clyn described life as “waiting amid death for death to come.”