Woman with facial syphilitic pustules, after a lithograph by Alibert in 1838. The patient is seen in the tertiary stage of infection, where the spirochaete bacterium Treponema pallidum is causing widespread permanent damage by the formation of chronic skin abcesses (gumma). Treatment in this stage can only arrest further spread of the disease: in the 19th century mercury was commonly used despite its toxic side-effects. Without treatment, the disease may cause loss of voluntary movement control (locomotor ataxia) or insanity (dementia paralytica).