Indirect hemagglutination antibody titers for Entamoeba Histolytica in dried filter paper blood and sera.

Serum and elutates from dried filter paper bloods from 404 patients with and without amebic liver abscess (ALA) were tested for Entamoeba histolytica antibodies by the indirect hemagglutination test. Eighty-nine percent of the sera from patients with ALA were positive (titers greater than or equal to 1 : 128) and 94% of those without ALA negative. Fifty-five percent of the filter paper bloods from ALA patients were positive. Overall agreement was 80% for positives and negatives and the correlation coefficient between the methods showed a linear relationship (r = 0.77). Although the quantity of sera available from dried filter paper bloods is limited and some antibody activity may be lost, the method should be of value in seroepidemiologic studies where venous bloods are not easily obtained.