A novel ELISA test for laboratory diagnosis of Blastocystis spp. in human stool specimens

Detection of Blastocystis is routinely performed by microscopy, culture, and formyl-ether (ethyl acetate) concentration technique (FECT). Yet, these methods require special skilled personnel, are time consuming, and often involve processing that may cause misdiagnosis. The aim of this work is to demonstrate the usefulness of a newly introduced ELISA test for the detection of Blastocystis antigens in stool samples (CoproELISA(TM) Blastocystis, Savyon Diagnostics) as a proper alternative to currently used methods, especially microscopy. A cohort of 179 fresh/frozen clinical stool samples was tested by the ELISA test, and results were compared to consensus methods comprised of microscopic examination of Lugol's iodine staining, culture, and immunofluorescence assay (IFA). The new ELISA test was able to detect fewer than 10(3) cells, recognized subtypes 1, 2, 3, and 5 (comprising >95 % of human Blastocystis infections), and exhibited similar reactivity when comparing formalin-preserved samples to fresh/frozen samples. The test demonstrated 92 % sensitivity, 87 % specificity, and 89 % accuracy when culture, and IFA or microscopy consensus results were taken as reference. When the consensus was comprised of culture and IFA, the test demonstrated sensitivity, specificity, and accuracy of 82, 86, and 84 %, respectively. In contrast, the sensitivity of Lugol staining microscopy was only 18 %. This work presents a unique ELISA test that provides an alternative to the use of microscopy, currently most widely used method. The test enables high-throughput screening and diagnosis of Blastocystis, adaptation to automatic procedures.