A single-step immunochromatographic lateral-flow assay for detection of Giardia lamblia and Cryptosporidium parvum antigens in human fecal samples.

RIDA Quick immunochromatographic lateral-flow assay was evaluated for diagnosis of giardiasis and cryptosporidiosis as compared to the "gold standard" stool examination. Of the 300 specimens were examined by microscopy of direct wet films, concentrated sediments, modified trichrome and modified Ziehl-Neelsen stained slides, 35 samples of Giardia, ten Cryptosporidium, 35 of other parasites, and 20 negative controls were selected for RIDA Quick test examination. All the samples that gave discrepancy results were retested by the centrifugation prior to preparation for the permanent stained smear. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of RIDA quick test for Giardia were 91.6%, 98.4%, 97% & 95.4% respectively, while that of the microscopic stool examination were 94.5%, 100%, 100% & 96.9%. The sensitivity, specificity, PPV and NPV of RIDA quick test for Cryptosporidium was 91.6%, 100%, 100% & 98.8% respectively, while that of the microscopic stool examination were 83.3%, 100%, 100% & 97.7%.