Treponema Pallidum

This illustration depicts a photomicrographic view of a Levaditi-stained culture specimen revealing the presence of numerous Treponema pallidum bacteria, 1979. Syphilis is passed from person to person through direct contact with a syphilis sore, known as a chancre, containing T. pallidum bacteria, and occurring mainly on the external genitals, vagina, anus, or in the rectum. Image courtesy CDC. (Photo by Smith Collection/Gado/Getty Images).