1. The Black Death, Reaching a crescendo of horror between 1348 and 1350, this plague remains the worst disease outbreak known to us in human history. It killed 75-100 million people…in other words, something like a fifth of the people then living in the world, including half the population of Europe. A disaster on that scale is hard for us to even get our heads around. But it happened.
Why “black”? At the time it was known predominantly as “the Great Plague or “the Great Pestilence,” but the name “Black Death” or “Black Plague” was given by later historians, not to indicate the appearance of necrosis experienced by sufferers (though in some cases people’s extremities did indeed turn black), but simply to emphasize the awful and seemingly apocalyptic nature of the pandemic.
The disease behind it all was the Yersinia pestis bacterium, the bubonic plague, spread by fleas parasitic to rats. The microbe was discovered in 1894 by a Pasteur Institute scientist studying an outbreak in Hong Kong. Thanks to the germ theory of disease and the later discovery of antibiotic therapy, bubonic plague is now thoroughly treatable. But the Black Death was only one of many catastrophic outbreaks of this disease, including the Plague of Justinian in 541 AD and the Third Pandemic that killed more than 12 million people starting in 1855, mostly in China and India.
2. Smallpox Comes to America
It’s hard to quantify the number of lives claimed by disease in the Americas after Europeans began colonizing, as we don’t have records, but consider this: the pre-Columbian population of North America was estimated to have been up to 18 million people. By 1900 the U.S. Census estimated there were 237,000 Indians in the United States. You do the math.
The ethnic cleansing of Native Americans through military means (which was substantial, when you look at the maps of a continent once teeming with native communities and now home to a tiny archipelago of reservations), probably played a much smaller part the ravages of plagues that decimated that population.
Smallpox was only the most prominent disease unknown to Indians and their immune systems, but there were many more: typhus, measles, influenza, bubonic plague, cholera, malaria, tuberculosis, mumps, yellow fever, and whooping cough. To take the example of one relatively well-documented tribe, over half the Wyandot (Huron) people were killed in one smallpox outbreak.
3. The 1918 Flu Pandemic
The so-called “Spanish flu” was the worst outbreak of infectious disease in the modern era, killing between 50 million and 130 million people all over the world. It became known as “Spanish” because Spain, as a neutral country in World War I, was not censoring the news at the time as Germany, England and others were doing. Indeed, with the peculiar mixture of widespread mobility and close quarters that war encourages, it and the plague exacerbated each other and made Europe a slaughterhouse.
The truly extraordinary thing about 1918-1919 was the speed with which the plague spread. It caused the kind of damage in a year that the Black Plague took a century (or that AIDS has taken a quarter-century) to wreak. It had a 10-20% mortality rate, unlike the usual 1% that most strains of influenza have. Like the recent swine flu epidemic, it was also disproportionately deadly to young adults, whereas the elderly are usually most vulnerable to disease.
Let us hope we never see its like again, but also let us prepare, in case something even worse should strike in our lifetimes.