- Syphilis is caused by the spirochete Treponema pallidum.
- Usually sexually transmitted
- Causes a wide range of systemic manifestations that are characterized by episodes of active disease interrupted by periods of latency
- Approximately 30% of asymptomatic contacts examined within 30 days of exposure have infection
- Spirochetes penetrate intact mucous membranes or microscopic dermal abrasions.
- Transmission through sexual contact with infectious lesions, infection in utero, blood transfusion, and organ transplantation
- Blood from a patient with incubating or early syphilis is infectious.
- Characterized by multiple stages separated by periods of latency: primary, secondary, latent and tertiary
[[File:Chancres on the penile shaft due to a primary syphilitic infection caused by Treponema pallidum 6803 lores.jpg|thumbnail|Chancres on the penile shaft due to a primary syphilitic infection]
- Primary lesion appears after an incubation of 2-6 weeks
- Single painless papule that becomes eroded and indurated, cartilaginous consistency on palpation
- Minority of patients can have multiple lesions or atypical appearance
- Occurs at point of contact: penis, rectum, mouth, external genitalia, cervix, or labia
- Heals in 4-6 weeks
- Regional lymphadenopathy that is painless and firm
- Benzathine penicillin G 2.4 million units IM x 1 (for primary or secondary infection)