Syphilis

Syphilis is caused by the spirochete Treponema pallidum and is transmitted primarily through sexual contact. After entering the body, the organism stimulates both humoral and cellular immune responses. The visible lesions and measurable antibody response are consequences of that interaction between organism and host. The illness changes appearance as infection progresses: - Primary syphilis commonly causes a chancre: a firm, usually painless ulcer at the site of inoculation. - Secondary syphilis reflects systemic illness and often causes a diffuse rash. A rash involving the palms and soles is a classic pattern. - Latent syphilis has no clinical manifestations, but serology remains positive. - Later disease can cause inflammatory injury such as gummas or cardiovascular syphilis. A lesion that does not hurt can be dismissed by the patient, especially if it is oral, genital, or anal and difficult to see. That is why a focused history and inspection matter. Pain is a clue, not a diagnostic rule: herpes lesions are often painful, but appearance alone cannot confirm or exclude syphilis.