TY - CHAP M1 - Book, Section TI - Syphilis: Natural History & Principles of Diagnosis & Treatment A1 - Philip, Susan S. A2 - Papadakis, Maxine A. A2 - McPhee, Stephen J. A2 - Rabow, Michael W. A2 - McQuaid, Kenneth R. PY - 2022 T2 - Current Medical Diagnosis & Treatment 2022 AB - Syphilis is a complex infectious disease caused by Treponema pallidum, a spirochete capable of infecting almost any organ or tissue in the body and causing protean clinical manifestations (Table 34–1). Transmission occurs most frequently during sexual contact (including oral sex) or via the placenta from mother to fetus (congenital syphilis). The risk of acquiring syphilis after unprotected sex with an individual with infectious syphilis is approximately 30–50%. Rarely, it can also be transmitted through nonsexual contact or blood transfusion. The immunologic response to infection is complex, but it provides the basis for most clinical diagnoses. The infection induces the synthesis of a number of antibodies, some of which react specifically with pathogenic treponemes and some with components of normal tissues (see below). If the disease is untreated, in most cases these immune reactions fail to eradicate existing infection and may contribute to tissue degeneration in the late stages. Patients treated early in the disease are fully susceptible to reinfection. The natural history of acquired syphilis is generally divided into two major stages: early (infectious) syphilis and late syphilis. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1184172469 ER -