The Plague of Justinian (541–542 CE, with recurrences for two centuries)

This was the first recorded pandemic caused by Yersinia pestis, the plague bacterium. It struck the Byzantine Empire during Emperor Justinian’s reign. Contemporary accounts describe cities losing up to half their populations. Some estimates put total deaths across the Mediterranean world at 25–50 million. It weakened the empire militarily and economically, changing the trajectory of European and Near Eastern history.

The Black Death (1346–1353)

This was the most infamous outbreak. It began in Central Asia, spread via trade routes, and devastated Europe, the Middle East, and North Africa. Mortality was catastrophic—between 30–60% of Europe’s population, roughly 75–200 million people. Beyond the death toll, it reshaped societies: labor shortages shifted economic power toward workers, feudal systems collapsed faster, and cultural attitudes toward death and religion transformed.

The Third Pandemic (1855–1960)

This began in Yunnan, China, spreading to India and beyond. It killed about 12 million people, most of them in India. This wave also carried plague to new continents through global shipping. It reached the United States (notably San Francisco in 1900) and Australia. Unlike earlier pandemics, this one occurred during the rise of bacteriology: in 1894, Alexandre Yersin identified Yersinia pestis, confirming the bacterial cause. This was crucial for modern medicine—without that discovery, plague would have remained an enigma.

The three pandemics together illustrate how one microbe repeatedly rewired human history. Each wave hit in different contexts—an empire, a medieval agrarian society, and a globalizing industrial world—and left behind different kinds of scars.

The End of Plague?

Plague hasn’t disappeared. Recently, a person in Arizona has died from plague, marking the first such death in the region in 18 years and highlighting that plague remains a present threat.

Today, plague remains endemic in some animal populations in the western US, with about seven human cases annually and very rare deaths. Globally, a few thousand cases occur each year, mostly in rural areas of countries like the Democratic Republic of the Congo, Madagascar, and Peru. Plague is treatable with common antibiotics if administered promptly.

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