As many as one in five Londoners had syphilis by their mid-30s during the late 18th century, according to a detailed new study on the sexually transmitted infection (STI) and its spread in the capital of the United Kingdom. Researchers used data from hospital admissions and workhouse infirmaries to reach their figures, making allowances for duplicate records, private treatments, and the possibility of syphilis numbers getting mixed in with other diseases like gonorrhea or chlamydia. The findings show a much higher incidence in London than elsewhere in the country at the time – other studies show 'the pox' was half...