Seroreactivity to syphilis in Malaysian blood donors and expectant mothers.

Over the period October 1973 to July 1975 sera from 8574 blood donors and 10096 expectant mothers were examined at the Serology Division Institute for Medical Research Kuala Lumpur. A Venereal Disease Research Laboratory (VDRL) slide test was performed as a screening procedure and all reactives were quantitated. As a confirmatory test the fluorescent treponemal antibody absorbed (FTA-ABS) test was performed on all VDRL reactive sera. The methodology recommended for both the VDRL and the FTA-ABS in the Manual of Tests for Syphilis was strictly followed. VDRL results were recorded as non-reactive weakly reactive (0 dilutions) or reactive (number of dilutions). FTA-ABS results were provided as reactive non-reactive or borderline. Borderline reactivity in the FTA-ABS was not given diagnostic significance and was considered with the non-reactives. The comparison in reactivity to serological tests for syphilis between the sera of blood donors and expectant mothers showed that 5.8% of blood donors and 3.3% of expectant mothers had reactive results with the VDRL. This difference was statistically highly significant (p 0.001. Biological false positivity rates for the entire populations studied were 1.05% and 1.21% respectively. This difference was not statistically significant. The distribution of FTA-ABS results for the different titres obtained in the VDRL test revealed that sera reactive to low titre in the VDRL had the highest proportion of biological false positives. Sera reactive to 32 dilutions and above showed no incidence of biological false positives. The high number of biological false positives in expectant mothers was possibly attributable to a higher incidence of conditions causing false positive reactions.