RAPID LATEX AGGLUTINATION-TEST FOR EXTRALUMINAL AMEBIASIS

Aims-To develop a rapid latex agglutination screening test for invasiv e amoebiasis. Methods-The performance of an in-house latex agglutinati on test was compared with three standard serological techniques-the im munofluorescent antibody test (IFAT), the indirect haemagglutination t est (IHA), and the cellulose acetate precipitin (CAP) test. Forty six sera were screened; 12 from negative controls; 10 sera from infections other than amoebiasis, and 24 sera from patients with luminal or extr aluminal infection with Entamoeba histolytica. Results-Strong positive latex agglutination reactions were observed, with 12 of 12 sera givin g combined CAP positive, IFAT positive, and IHA positive results. Thes e results are indicative of invasive amoebiasis. Twelve CAP negative, IFAT positive sera, and 10 of 12 IHA negative gave weak or negative ag glutination reactions. One of 12 CAP negative, IFAT positive, and IHA positive sera gave a strong positive latex agglutination result; one w ith CAP negative, IFAT positive, and IHA positive sera gave a weak lat ex agglutination reaction. These results correlate with either treated amoebiasis or with the early stages of invasive amoebiasis for which the CAP test is known to have a lower sensitivity than the IFAT, but a higher specificity. No reactions were observed with 12 out of 12 CAP negative, IFAT negative, and IHA negative control sera and all 10 sera from other infections (two giardiasis, three schistosomiasis, three m alaria, one filariasis). Conclusions-The latex agglutination test was a useful indicator test, paralleling the results obtained with standar d serological techniques. It could also be a useful screening tool in the field.