Chapter 11.5 : Laboratory Diagnosis of Syphilis

Abstract:

Syphilis is a sexually transmitted disease that is caused by the organism Treponema pallidum subsp. pallidum. The disease goes through several stages if untreated ( 2 , 15 ). The primary chancre occurs at the site of inoculation approximately 3 to 4 weeks (range, 10 to 90 days) after the initial exposure. Treponemes may be visualized in lesion exudates using either dark-field microscopy or direct fluorescent antibody for T. pallidum (DFA-TP). About 7 to 10 days after the chancre appears, antibodies to T. pallidum are detectable using the routine serologic tests for syphilis. The chancre spontaneously heals after 1 to 4 weeks. The symptoms of secondary syphilis appear about 6 weeks later (range, 2 weeks to 6 months). All serologic tests are generally reactive during secondary syphilis. The most common symptoms are a generalized or localized maculopapular rash that occurs on the palms of the hands and soles of the feet (palmar plantar rash) or on the trunk of the body, mucosal membrane lesions, generalized lymphadenopathy, and condylomata lata. These symptoms will resolve without treatment. The patient then enters a period of latency when there are no symptoms. In about 20 to 25% of individuals, secondary symptoms may reoccur during the early part of this latent period. In early latency (<1 year) the results for the serologic tests for syphilis are reactive. As patients progress into late latency, the nontreponemal tests may become nonreactive, but the treponemal tests will remain reactive. About 65% of persons with untreated syphilis will remain in this stage for life ( 15 ). In the remaining 35%, late manifestations of syphilis will occur.