[Reactivity of serologic tests for the detection of syphilis in patients infected with the human immunodeficiency virus]

Abstract

Background: The coexistence of syphilis and infection by the human immunodeficiency virus (HIV) appears to modify the natural history of both diseases. The aim of this study was to know the prevalence of syphilis in a population of patients with HIV infection, the possible association with certain risk practices and the validity of the reaginic test in such patients.

Methods: Three hundred sixty-seven patients with HIV infection who went for the first time to a monographic clinic of a university hospital were studied. Syphilis serology was carried out: rapid plasma reaginic (RPR) and hemagglutination (MHA-TP) tests.

Results: Out of all the patients 26 (7.1%) had positive MHA-TP. The proportion of homosexuals was greater among those who had a positive treponemic test (69%) than among those who were negative (6.4%; odds ratio [OR] = 32.6; confidence interval 95%: 16.2-65.4). The positivity of MHA-TP was more frequent among those presenting criteria of the acquired immunodeficiency syndrome (AIDS) at the diagnosis (18% versus 5.6%; OR = 3.6 [1,5-8,9]). Seventy-four false positive reactions were observed with the RPR (20%) corresponding almost exclusively (96%) to intravenous drug users who presented false positivity in 25% of the cases.

Conclusions: The prevalence of syphilis detected by treponemic serology among subjects with infection by the human immunodeficiency virus is related with homosexuality as the principal practice of risk. One quarter of the intravenous drug users with infection by the human immunodeficiency virus presented false positive results to the reaginic test thus leading to the recommendation that therapeutic measures should not be initiated without confirmation with a treponemic test.