Syphilis sero-positivity in recently admitted and long inpatients : screening, prevalence and diagnostic profile

Abstract

BACKGROUND: Syphilis research has neglected the prevalence of the disease among psychiatric patients, and traditional syphilis screening has been reported as inadequate. OBJECTIVES: (i) To assess the syphilis prevalence among psychiatric patients; (ii) to compare psychiatric diagnoses of syphilis-infected and -uninfected patients; (iii) to assess self-reported high-risk sexual behaviour; (iv) to establish syphilis/HIV co-morbidity; and (v) to investigate the performance of the rapid plasma reagin (RPR) test in syphilis screening, compared with the Treponema pallidum haemagglutination (TPHA) test. METHODS: Psychiatric inpatients at Weskoppies Hospital, Pretoria, who consented to participate in the study (N=195) were categorised according to gender and length of admission (long-term or recent). Non-treponemal RPR, confirmatory TPHA, HIV-rapid and HIV enzyme-linked immunosorbent assay (ELISA) tests were performed. A reactive TPHA test was used to diagnose syphilis. RESULTS: The estimated prevalence of syphilis was 11.7%. There was no significant association between TPHA sero-positivity and primary psychiatric diagnosis or self-reported high-risk sexual behaviour. Significant co-morbidity existed between syphilis and HIV (p=0.012). Compared with the TPHA test, the RPR test performed poorly, identifying only 2/23 patients who had a sero-positive TPHA test (8.7% sensitivity and 100% specificity). CONCLUSIONS: The prevalence of syphilis was higher than anticipated, supporting the need for routine testing. The significant co-morbidity and alarming prevalence of HIV and syphilis warrant testing for both conditions in all psychiatric admissions. Current syphilis screening with a single RPR test is inadequate; both RPR and TPHA tests should be performed.