Rapid plasma reagin card test: evaluation of a hand-rotation procedure and stability of the RPR antigen.

Reported are the results of a comparative study of two procedures for the rapid plasma reagin (RPR) test for syphilis serology: in one approach a mechanical rotator was used and in the other, hand rotation was employed. Both procedures were performed on 327 sera. The agreement between both was 98.8%. Three sera that exhibited minimal reactivity (titre = 1) in the mechanical-rotation RPR were nonreactive in the hand-rotation RPR. RPR antigen was stored for 3 months at room temperature (mean, 21 degrees C) and 30 degrees C. There was no difference in the reactivity of 62 sera (50 positive, 12 negative) that were tested using either adversely stored antigens or antigen stored at 4 degrees C. In poorly equipped settings at the primary health care level, the hand-rotation RPR is a practical alternative to mechanical rotation. Also, the stability of the antigen under adverse storage conditions is an additional advantage of RPR for use in tropical areas.