Syphilis came from the Americas
Casanova appears to have escaped the disfigurements of skin sores on the face and genitals, the "purple flowers" or lesions caused by syphilis (Treponema pallidum).
But his memoir is full of lively anecdotes about syphilis and other STI's, some of which he was responsible for spreading, like in this conversation with a Croatian doctor:
You had a connection with Don Jerome's housekeeper, and you left her, when you went away, a certain souvenir which she communicated to a friend of hers, who, in perfect good faith, made a present of it to his wife. This lady did not wish, I suppose, to be selfish, and she gave the souvenir to a libertine who, in his turn, was so generous with it that, in less than a month, I had about fifty clients. The following months were not less fruitful, and I gave the benefit of my attendance to everybody, of course, for a consideration. There are a few patients still under my care, but in a short time there will be no more, as the souvenir left by you has now lost all its virtue. You can easily realize now the joy I felt when I saw you; you are a bird of good omen. May I hope that your visit will last long enough to enable you to renew the source of my fortune?"
In Casanova's time, mercury was the primary way to treat skin diseases in Europe. Indeed, it was a popular treatment from the 14th century into the 20th when antibiotics were discovered. While mercury was antimicrobial, at some point the treatment became worse than the disease. Below is Dürer's take on the subject:
Evidently, syphilis came to Europe from the Americas when Columbus' crew returned in 1493. In one of those ironies of history, while measles and smallpox were going to the Americas, syphilis ravaged Europe in return. Interestingly, recent research suggests that "the disease may not have evolved into a sexually transmitted form until the time of contact." When the French King invaded Italy in 1494 with an army of mercenaries, syphilis went along too and this new and dangerous mutation became known as the "French disease." By 1500 it was everywhere in Europe and, as with every pandemic, everyone blamed the country next door.
That epidemic in Italy in the 1490's significantly impacted all the powerful families (the Borgias, Sforzas, etc.) and the clergy. Unfortunately, subsequent European exploration conveyed the disease to the rest of the world. Below is Hans Holbein the Younger's Head of a Young Man (1523). Most art historians suspect the man has syphilis; a few argue it's something else.
