The Worst Outbreaks of All Time

Source: Wellcome Images / Wikimedia Commons

10. Antonine Plague
> Death toll: 5 million
> Disease/Cause: Unknown-Smallpox or measles
> Affected area: Asia Minor, Egypt, Greece, and Italy
> Duration: A.D. 165

The disease decimated the Roman army, forcing Emperor Marcus Aurelius to use Germanic troops under Germanic commanders to maintain the empire. This was the first step in de-Romanizing the empire’s legions

Source: Library of Congress / Wikimedia Commons

9. Smallpox in Mexico
> Death toll: 5-8 million
> Disease/Cause: Smallpox
> Affected area: Mexico
> Duration: 1519-1520

The Spanish conquest of what is now Mexico was accelerated by the introduction of smallpox to the indigenous population. It was the start of one of the greatest depopulation events in the history of humankind.

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8. Modern Plague
> Death toll: 10 million
> Disease/Cause: Bubonic plague
> Affected area: India, China, parts of other areas around world
> Duration: 1894-1903

In 1897, during the epidemic in India, Paul-Louis Simond and Masanori Ogata separately discovered the role of fleas in the transmission of plague. Two years earlier, Alexandre Yersin, Albert Calmette, and Améndée Borrel developed the first form of immunization against plague.

Source: Rafael Monleón Torres / Wikimedia Commons

7. Cocoliztli
> Death toll: 12-15 million
> Disease/Cause: Hemorrhagic fevers/smallpox
> Affected area: Mexico
> Duration: 1545-1548

The epidemic of cocoliztli from 1545 to 1548 killed as many as 15 million people, or up to 80% of the native population of Mexico. In characterizing this calamity, Rodolfo Acuna-Soto, a professor of epidemiology at Universidad Nacional Autonoma de Mexico said, “In absolute and relative terms the 1545 epidemic was one of the worst demographic catastrophes in human history, approaching even the Black Death.”

Source: Thomas H. Hahn / Wikimedia Commons

6. The Third Plague Pandemic
> Death toll: 12-15 million
> Disease/Cause: Bubonic plague
> Affected area: Worldwide
> Duration: 1855-1950s

The pandemic originated in China’s Yunnan province. It eventually moved to Hong Kong and Guangzhou, both major shipping hubs, and the disease was transported all over the world by the end of the 19th century. It was at this time that science was making significant progress in identifying how fleas were the cause of the outbreak.