Diagnostic biologique de la syphilis et des tréponématoses endémiques. Une nécessaire actualisation des connaissances

Abstract

Treponematoses, including syphilis, yaws, bejel, carate and pinta are worldwide infectious diseases. Their incidence, however, varies between countries. There was an increasing incidence of syphilis in the USA during the last decade contrasting with a continuous decrease in Europe. Such a low apparent frequency of a communicable infection may lead to the loss of knowledge of etiological diagnosis and thus, exposes to the emergence of complicated forms since early typical forms, which are easy to cure, may be misdiagnosed and underevaluated. Apart from direct detection of Treponema pallidum by microscopy in early cutaneous and mucosal lesions, most of the biological diagnostic methods are based on detection of serum antibodies. The combination of anticardiolipin tests (VDRL, RPR) with specific T. pallidum antigens passive hemagglutination (TPHA) are useful screening tests with an overall sensitivity of 84 %. Fluorescent treponemal antibodies specific assay (FTA-abs) is a reliable confirmatory test. Active infection, including early syphilis, relapse, and reinfection is associated with rising of specific IgM antibodies. Their detection and titration is crucial for the diagnosis of congenital syphilis in the newborn. Additional new tests are under evaluation which may improve the biological diagnosis of treponematoses. They include ELISA's, immunoblotting and gene amplification (PCR). These new tests may help the diagnosis of all clinical forms including the sometimes difficult problem of diagnosing syphilis in HIV patients. From the epidemiological point of view, the use of careful diagnostic procedures to detect syphilis in low incidence countries, such as Europe, might permit the eradication of this infection which only reservoir is man, and which can efficiently be cured with penicillin. © 1995.