Comparison of Kato–Katz Direct Smear and Sodium Nitrate Flotation for Detection of Geohelminth Infections

Abstract

Two hundred eighty-one stool samples were comparatively examined for the presence of ova of Ascaris lumbricoides, hookworms, and Trichuris trichiura using the traditional Kato–Katz technique and Ovassay® Plus (Synbiotics Corp., San Diego, California) with a sodium nitrate solution to test the hypothesis that use of a commercially available flotation kit would provide a faster, cleaner, and more effective means of detecting geohelminth infections in human helminthological surveys than the traditionally used Kato–Katz direct-smear technique. Fecal flotation was as effective as Kato–Katz in detection of ova of Ascaris lumbricoides; however, it was not as effective in detecting ova of Trichuris trichiura. There was no significant difference in the prevalence of hookworm infection revealed by the 2 techniques when Kato–Katz preparations were viewed within an hour of preparation; however, after 1 hr, the effectiveness of Kato–Katz in the detection of hookworm ova declined significantly.