In the 18th and 19th century, scientists often used themselves as guinea pigs in the course of conducting experiments to determine the causes of disease and test the efficacy of new drugs.
One of the earlier and more heroic examples comes from the Scottish physiologist and surgeon John Hunter (1728-93). Hunter was investigating syphilis, a disease surrounded by secrecy and shame whose origins were unlikely to be acknowledged at any level. The French called it the Italian disease and the Italians called it the French disease.