A comparative study of different methods used in the detection of Giardia lamblia on fecal specimens of children

Objective: The purpose of this study was to compare results obtained using a single fecal specimen for ova and parasite (O and P) examination, direct immunofluorescent assay (DFA), and two conventional staining methods. Design: Fecal specimens of 150 children were collected and examined by each method. The O and P and the DFA were used as the reference methods. Setting: The study was performed at the laboratory in the Basic Medical Science Institute JPMC Karachi. Materials and Methods: The fecal specimens were collected from children with a suspected Giardia lamblia infection. Agreement and disagreement between the methods was determined based on (1) the presence of giardiasis in our population and (2) the sensitivity and specificity of each method. Results: There was 45 (30%) positive and 105 (70%) negative cases found with DFA, 41 (27.4%) positive and 109 (72.6%) negative cases detected by iodine method, and 34 (22.6%) positive and 116 (77.4%) negative cases found with saline method. The sensitivity and specificity of DFA in comparison to iodine were 92.2 and 92.7%, respectively. The sensitivity and specificity of DFA in comparison to saline method were 91.2 and 87.9%, respectively. The sensitivities of iodine method and saline method in comparison to DFA were 82.2 and 68.8%, respectively. There is marked difference in sensitivity of DFA compared to conventional methods. Conclusion: The study supported the findings of other investigators who concluded that DFA method has the greatest sensitivity. The immunologic methods were more efficient and quicker than the conventional O and P method.