It has often been called the great imitator because so many of the signs and symptoms are indistinguishable from those of other diseases. The syphilis bacterium is passed from person to person through direct contact with a syphilis sore. Sores mainly occur on the external genitals, vagina, anus, or in the rectum.
Sores also can occur on the lips and in the mouth.
Transmission of the organism occurs during vaginal, anal, or oral sex. Pregnant women with the disease can pass it to the babies they are carrying. Syphilis cannot be spread by toilet seats, door knobs, swimming pools, hot tubs, bath tubs, shared clothing, or eating utensils. The chancre is usually firm, round, small, and painless. It appears at the spot where the bacterium entered the body.