Biological false positive serological tests for syphilis among drug addicts

Abstract

Sera from 1,646 drug abusers were screened for biological false positive reactivity. Using the VDRL and FTA-ABS tests, the prevalence was 8-7 per cent., approximately ten times greater than that in the general population. A second group of sera from 197 addicts screened with four reagin tests and three treponemal tests, showed a 6-1 per cent. prevalence of BFP reactions. In addition, this group had 'treponemal false positive' reactions, and patterns of serological reactivity that could not be readily categorized. Hence, reagin tests in drug abusers should be confirmed by treponemal tests, and treponemal tests should be performed only in conjunction with reagin tests. No significant associations could be found between BFP reactions and particular aspects of drug use, liver disease, or gonorrhoea.