Bubonic Plague Research
Photograph by the National Library of Medicine/Science Photo Library
In 1914, during an outbreak of bubonic plague in New Orleans, scientists dissect rats suspected of having the disease. Research plus rat-proofing and rat-catching measures helped contain the outbreak—bubonic plague's last major stand in the United States—to a few dozen victims and only ten deaths. Carried by fleas from rodents to humans, bubonic plague cannot pass from human to human.