Since the 15th century, doctors had recognized syphilis as a discrete disease. Because of its mild initial symptoms, however, only in the late 19th century did doctors realize the full damage syphilis can inflict on the nervous system, including blindness, deformity, insanity, and death. Unfortunately, doctors could do little to help those with syphilis. The best available treatment consisted, essentially, of poi- soning patients with arsenic and other heavy metals in the hopes that these poisons would kill whatever had caused the disease before they killed the patients.
In 1905, scientists first identified the bacterium Treponema pallidum as the cause of syphilis. Five years later, Paul Ehrlich discovered the drug Salvarsan as a cure for syphilis. An arsenic derivative, Salvarsan was the first drug to successfully target a specific microorganism. As such, it opened the modern era of medical therapeutics. After this point, those who sought early treatment for syphilis could expect a complete cure, whereas those who put off treatment risked irreversible neurological damage and a horrible death.