infectious diseases
Syphilis
Introduction
Syphilis is caused by the spirocheteTreponema pallidumand is characterized by 3 sequential symptomatic stages separated by periods of asymptomatic latent infection. Common manifestations include genital ulcers, skin lesions, meningitis, aortic disease, and neurologic syndromes. Diagnosis is by serologic tests and adjunctive tests selected based on the disease stage. Penicillin is the treatment of choice. (See also Overview of Sexually Transmitted Infections and Syphilis is caused byT. pallidum, a spirochete that cannot survive for long outside the human body.T. pallidumenters through the mucous membranes or skin, reaches the regional lymph nodes within hours, and rapidly spreads throughout the body. In 2020, there were more than 130,000 reported cases of syphilis in the US. The majority of cases of primary and secondary syphilis occurred in men (81%) and, among men, 53% of cases were in men who have sex with men. The incidence of syphilis has been increasing rapidly in the US; from 2015 to 2020, the primary and secondary syphilis rate among women increased 147% (from 1.9 to 4.7 per 100,000), and the rate among men increased 34% (from 15.5 to 20.8 per 100,000) (see Centers for Disease Control and PreventionPreliminary 2021 STD Surveillance DataandSexually Transmitted Disease Surveillance 2020: Syphilis). Syphilis occurs in 3 stages (see table): Primary Secondary Tertiary There are long latent periods between the stages. Infected people are contagious during the first 2 stages. Infection is usually transmitted by sexual contact (including genital, orogenital, and anogenital) but may be transmitted nonsexually by skin contact or transplacentally, causing Congenital Syphilis . Risk of transmission is about 30% from a single sexual encounter with a person who has primary syphilis and 60 to 80% from an infected mother to a fetus. Infection does not lead to immunity against reinfection. 