Syphilis sero-positivity in recently admitted and long-term psychiatric 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.