What occurs during the primary stage of syphilis?

• A. Fever with generalized malaise and diffuse rash.
• B. Localized itching at the exposure site with transient rash.
• C. Immediate numbness at the exposure site.
• D. Penetration of the skin during intercourse, forming an ulcer or chancre 2-3 weeks after exposure.

Answer: (D)

During the primary stage, the infection starts at the site where Treponema pallidum enters the body during sexual contact. About 2–3 weeks after exposure, a painless ulcer, called a chancre, forms at that entry site. The chancre has indurated borders and a clean base, and nearby lymph nodes may enlarge. This lesion is highly infectious, and it often heals on its own within 3–6 weeks even without treatment. Other symptoms like fever, generalized malaise with a diffuse rash, or numbness belong to later stages, not the primary stage. So the defining event is the inoculation through the skin and the development of a painless chancre at the entry site after a few weeks.