Declining trend of serological syphilis among genitourinary medicine patients in the Gambia, West Africa.

Background: Syphilis is a common disease in Africa and may be an important contributor to the HIV epidemic. Trends in syphilis prevalence are important in their own right and because syphilis is a cofactor for HIV infection. In this study we analyzed trends in serological syphilis prevalence at a sexually transmitted infections (STI) clinic in The Gambia.

Methods: At the Genitourinary Medicine clinic of the Medical Research Council in The Gambia patients were routinely screened for syphilis using a 2-test algorithm, measuring rapid plasma reagin followed by the Treponema pallidum haemagglutination assay. Serological syphilis was defined as both tests being positive. We determined year to year trends in serological syphilis. Logistic regression was used to identify risk factors.

Results: Over the period 1994-2007, 23,674 people were tested for syphilis. The prevalence of serological syphilis dropped from 11.2% in 1994 to 1.5% in 2007 (P <0.0001; chi test for trend). Significant risk factors for serological syphilis in women were found to be ethnicity, commercial sex work, and HIV infection. No associations between serological syphilis and possible risk factors in men were found.

Conclusions: This study identified a strong and significant downward trend in the prevalence of serological syphilis among patients attending the Genitourinary Medicine clinic in The Gambia in the period 1994-2007. These results suggest that syphilis prevalence may be declining in the general population, in the absence of a targeted control program. Research is needed to identify the reasons for this decline.