It then began to appear in adults who were unable to fend off the infection because they had never been exposed as children, and they readily spread it via sexual contact to other adults who also had limited or no resistance, causing deformity and death where before it had been only been a temporary childhood ailment. This transition is reported to have coincided temporally with the return of the Columbus expedition from the New World. The most compelling evidence for its validity is the presence of syphilitic-like damage to bones in a number of adult skeletons found in the British city of Hull who were buried over a century before Columbus made his journey to the Americas.More recent analysis of that research, however, concluded in 2012 that syphilis almost certainly had a New World origin.The causative organism, Treponema pallidum, was first identified by Fritz Schaudinn and Erich Hoffmann, in 1905. The first effective treatment for syphilis was arsphenamine, discovered by Sahachiro Hata in 1909, during a survey of hundreds of newly synthesized organic arsenical compounds led by Paul Ehrlich. It was manufactured and marketed from 1910 under the trade name Salvarsan by Hoechst AG. This organoarsenic compound was the first modern chemotherapeutic agent. During the 20th century, as both microbiology and pharmacology advanced greatly, syphilis, like many other infectious diseases, became more of a manageable burden than a scary and disfiguring mystery, at least in developed countries among those people who could afford to pay for timely diagnosis and treatment.
The Columbian hypothesis is better supported by the evidence and findings from phylogenetic science suggest that it is, in fact, a New World disease.The timing of the arrival of syphilis in Europe certainly supports the above theory, Columbus having journeyed in 1492. The first written records of an outbreak of syphilis in Europe occurred in 1494 or 1495 in Naples, Italy, during a French invasion (Italian War of 1494–98). Since it was claimed to have been spread by French troops, it was initially called the "French disease" by the people of Naples. The disease reached London in 1497 and was recorded at St Batholomews Hospital as infected 10 out of the 20 patients. In 1530, the pastoral name "syphilis" (the name of a character) was first used by the Italian physician and poet Girolamo Fracastoro as the title of his Latin poem in dactylic hexameter Syphilis sive morbus gallicus (Syphilis or The French Disease) describing the ravages of the disease in Italy. In Great Britain it was also called the "Great Pox".In the 16th through 19th centuries, syphilis was one of the largest public health burdens in prevalence, symptoms, and disability,: 208–209  although records of its true prevalence were generally not kept because of the fearsome and sordid status of sexually transmitted infections in those centuries. : 208–209  According to a 2020 study, more than 20% of individuals in the age range 15–34 years in late 18th century London were treated for syphilis.