Pattern of reactive serological tests for syphilis in different population groups attending the University College Hospital Ibadan (1976-1985)

Abstract

A review of the reactive serological tests for syphilis was carried out. An overall seroreactivity of 5.1% was obtained over the 10-year period reviewed. A subtle but steady rise in the incidence of syphilitic infections was noted, from 7 to 10 new cases per 1000 population between 1970 and 1975. The predictive characteristics obtained from the screening tests show that the tests are reliable diagnostic tests when the results are carefully interpreted, and the medical personnel can be alerted of the prevalence of syphilitic infections.

PIP: Serological tests for syphilis conducted at the University College Hospital, Ibadan, Nigeria, from 1976-1985 were compared to results from 1970-1975, showing a clear increase in prevalence. The departments participating were the antenatal care, special treatment (venereal disease), outpatient, wards, and blood bank. For most of the decade, sera and verified with the TPHA (Treponema pallidum hemagglutination test) test, although data were also available from the 1st half of the period from initial screening with the RPR (Rapid Plasma Reagin) test. The overall positive rates were 5.1% with the VDRL, 7.7% with the TPHA test, and 2.8% with the RPR test. The lowest rate of reactive sera by the VDRL was the antenatal clinic, with 2.3%, and the highest were the outside-hospital clinics, with 7.6%. Using the TPHA test as a reference, the sensitivity of the VDRL was 54.7%, and its specificity was 94.7%. Considering a positive titer of 1:4 as reactive, 0.995% of the VDRL tests were positive, giving a syphilis incidence of 10/1000. This is an increase of 3 cases/1000 above the rate found in the previous decade. The results are plausible considering the rapid increase in new cases of other STDs (sexually transmitted diseases).