Objective: To evaluate the sensitivity and specificity of three laboratory techniques for the diagnosis of Giardia intestinalis. Materials and Methods: 31 fecal samples from pre schoolers were submitted to microscopic examination with SSF-Lugol, the Ritchie concentration method and the “Giardia-Strip” immunological method. The Ritchie technique was considered the “gold standard.“ Results: G. intestinalis cysts were identified in 6 samples (19.35%) using the Ritchie technique. The fresh test identified 5 cases of protozoan cysts (16.1%), showing a sensitivity of 83 % and specificity of 100 %. The Giardia-Strip identified cysts in 4 samples (12.9%) with 66.66 % sensitivity and 100% specificity. The positive predictive value for the “Giardia Strip” method was 14% and the negative predictive value was 93%. The fresh test showed a positive predic tive value of 100% and a negative predictive value of 96 %. Conclusions: Ritchie concentrate and the fresh test showed higher sensitivity and specificity in the diagnosis of Giardia intestinalis, when samples contain only cysts. However, the Giardia-Strip method proved faster in obtaining results.
