Graduate student Jennifer Klunk of McMaster University examines a tooth used to decode the genome of the ancient plague. Courtesy of McMaster University hide caption

itoggle caption Courtesy of McMaster University

Yoset, a spiritual healer near Arua, Uganda, works with the Centers for Disease Control and Prevention to detect the plague in his village. Courtesy of Mary Hayden hide caption

itoggle caption Courtesy of Mary Hayden

A copper engraving from 1656 shows a plague doctor in Rome wearing a protective suit and a mask. Artwork by Paul Furst /Wikimedia.org hide caption

itoggle caption Artwork by Paul Furst /Wikimedia.org

Victims of the plague are consigned to a communal burial during the Plague of London in 1665.

Universal Images Group/Getty Images hide caption

itoggle caption Universal Images Group/Getty Images