Viruses, Plagues, and History: Past, Present, and Future

More people were killed by smallpox during the twentieth century—over 300 million—than by all of the wars of that period combined. In 1918 and 1919, influenza virus claimed over 50 million lives. A century later, influenza is poised to return, ongoing plagues of HIV/AIDS and hepatitis infect millions, and Ebola, Zika, and West Nile viruses cause new concern and panic.

The overlapping histories of humans and viruses are ancient. Earliest cities became both the cradle of civilization and breed...