Few people today call a doctor when they feel a bout of nostalgia coming on. But for 200 years, nostalgia was considered a dangerous disease that could trigger delusions, despair, and even death. A 17th-century Swiss physician coined the word to describe the debilitating algos (pain) felt by people who had left their nostos (native home). In the U.S. during the Civil War, Union Army doctors reported 5,000 serious cases of nostalgia, leading to 74 deaths. In Europe, physicians anxiously debated how to treat home-sickness and contain its spread.