IGM ANTIBODY-CAPTURE HAEMADHERENCE TEST (MACHAT) FOR THE DETECTION OFMEASLES SPECIFIC IGM

An antibody capture haemadherence test (MACHAT) for detecting measles- specific IgM is described. The assay is based on the antibody capture principle with rhesus monkey erythrocytes as detector system in place of labelled antisera. MACHAT was compared with a commercial indirect e nzyme immunoassay (EIA) for measles-specific IgM using 382 sera from p atients notified as measles. There was good agreement between the two tests; 106 sera were found to contain measles IgM by both tests, 7 fur ther sera were positive only in the commercial EIA and 9 only in MACHA T. One sera gave an equivocal result in MACHAT and another in the comm ercial EIA. Twelve of the 18 sera with discrepant results were also te sted by MACRIA; in 7 MACRIA gave the same results as MACHAT, in 3 the MACRIA results agreed with the commercial test and in 2 the MACRIA res ults were equivocal. Specificity was established by a lack of MACHAT r eactivity in sera collected from blood donors (n = 83) and from cases of recent rubella, dengue and parvovirus B19 infection (n = 51). The M ACHAT is a simple, cheap test that can be read by eye and is suitable for measles surveillance programmes in the developing world.