What disease is caused by the bacterium Treponema pallidum?

The disease caused by the bacterium Treponema pallidum is syphilis. More precisely, syphilis is caused by the subspecies Treponema pallidum pallidum, a thin, spiral-shaped bacterium known as a spirochete. It was first identified in syphilitic lesions in 1905 by Fritz Schaudinn and Erich Hoffmann in Berlin.

Syphilis usually spreads through sexual contact, when the bacterium enters through mucous membranes or tiny breaks in the skin. It can also cross the placenta during pregnancy, causing congenital syphilis. The infection commonly progresses through primary, secondary, latent and, in some untreated cases, tertiary stages. Later disease can damage the heart, brain, eyes, bones and nervous system.

A common mix-up is that Treponema pallidum is also the species name for closely related subspecies causing yaws and bejel. However, the standard quiz and medical answer for this bacterium is syphilis. The organism is highly sensitive to penicillin, which remains the principal treatment.