Primary thumb|Chancre on a penis due to primary syphilis, 1978 Primary syphilis is typically acquired by direct sexual contact with the infectious lesions of another person. Approximately 2–6 weeks after contact (with a range of 10–90 days) a skin lesion, called a chancre, appears at the site and this contains infectious bacteria. This is classically (40% of the time) a single, firm, painless, non-itchy skin ulceration with a clean base and sharp borders approximately 0.3–3.0 cm in size. The lesion may take on almost any form. In the classic form, it evolves from a macule to a papule and finally to an erosion or ulcer. Occasionally, multiple lesions may be present (~40%), with multiple lesions being more common when coinfected with HIV. Lesions may be painful or tender (30%), and they may occur in places other than the genitals (2–7%). The most common location in women is the cervix (44%), the penis in heterosexual men (99%), and anally and rectally in men who have sex with men (34%). Lymph node enlargement frequently (80%) occurs around the area of infection, occurring seven to 10 days after chancre formation. The lesion may persist for three to six weeks if left untreated.
Primary thumb|Chancre on a penis due to primary syphilis, 1978 Primary syphilis is typically acquired by direct sexual contact with the infectious lesions of another person. Approximately 2–6 weeks after contact (with a range of 10–90 days) a skin lesion called a chancre, appears at the site and this contains infectious bacteria. This is classically (40% of the time) a single, firm, painless, non-itchy skin ulceration with a clean base and sharp borders approximately 0.3–3.0 cm in size. The lesion may take on almost any form. In the classic form, it evolves from a macule to a papule and finally to an erosion or ulcer. Occasionally, multiple lesions may be present (~40%), with multiple lesions being more common when coinfected with HIV. Lesions may be painful or tender (30%) and they may occur in places other than the genitals (2–7%). The most common location in women is the cervix (44%), the penis in heterosexual men (99%), and anally and rectally in men who have sex with men (34%). Lymph node enlargement frequently (80%) occurs around the area of infection, occurring seven to 10 days after chancre formation. The lesion may persist for three to six weeks if left untreated.