Evaluation of a new bicolored latex agglutination test for immunological diagnosis of hepatic amoebiasis.

A new bicolored latex agglutination amoeba test (BLA) for detection of antibodies against Entamoeba histolytica was evaluated for its practicability and diagnostic sensitivity and specificity. BLA is rapid (5 min) and simple to perform. It requires only 20 microliters of a 1/3-diluted serum, 17 microliters of reagent, and a glass slide. Reading of the test is easy because a positive result shows a green spot with a red surrounding edge. This bicolored pattern is easily distinguishable from the negative test result, which shows a homogeneous dark-brown spot. By using serum samples from 348 individuals, BLA was compared with immunofluorescence assay, indirect hemagglutination, and counterimmunoelectrophoresis. Sensitivity, specificity, efficiency, and positive and negative predictive values of the four methods were almost identical. The results of this study indicate that BLA could be very useful both as a screening method for the diagnosis of invasive amoebiasis and for epidemiological purposes.