Syphilis
Syphilis used to be very common, and it caused sickness and death all over the world. It was especially very common in Europe during the 18th and 19th centuries. During the early 20th century, syphilis quickly became less common in the developed world, because antibiotics were being used more and more. Syphilis kept becoming less common until the 1980s and 1990s. Since the year 2000, syphilis is getting more common again in the United States, the United Kingdom, Australia, and Europe, mostly among men who have sex with men.