Evaluation of Enzyme Linked Immunosorbent Assay (ELISA) and Dot ELISA for Diagnosis of Amoebiasis.

Introduction: This study was conducted to evaluate the usefulness of dot enzyme-linked immunosorbent assay (dot ELISA) and plate ELISA, using monoxenically-grown Entamoeba histolytica soluble crude antigen, for detecting antiamoebic antibodies in serum samples from suspected amoebic patients and healthy controls.

Materials and Methods: Sera from 18 suspected amoebic patients, 15 healthy subjects and 13 patients with other parasitic diseases (leishmaniasis, hydatidosis, ascariasis and trichostrongyloidiasis) were examined for the presence of specific Entamoeba histolytica antibodies by ELISA and dot-ELISA. Both dot and plate ELISA detected antiamoebic antibodies in 15 (out of 18) suspected amoebic.

Results: From 15 healthy controls, two sera were found to be positive by ELISA and one of these two was also positive by dot-ELISA. In both assays, no cross reaction was found with the sera from other parasitic diseases including leishmaniasis, hydatidosis, ascariasis and strongyloidiasis. Sensitivity of the ELISA system was determined as 83.3% (95% CI: 57.7-95.6%) and the specificity was found to be 92.5% (95% CI: 74.2-98.7%). Positive and negative predictive values of the system were 88% and 89% respectively. On the other hand, sensitivity of the dot-ELISA was determined as 83.3% (95% CI: 57.7-95.6%) and the specificity was found to be 96.3% (95% CI: 79-99.8%). Positive and negative predictive values of dot ELISA were 93.7% and 89.6% respectively.

Conclusion: While the sensitivity of both assays were equal (83.3%), dot-ELISA was found to be more specific (96.3%) in detecting antiamoebic antibodies compared to Plate ELISA (92.5%). Seeing that the dot ELISA is simpler, rapid, inexpensive, equally sensitive and more specific as compared to plate ELISA, its use in serodiagnosis of amoebiasis can be recommended.