Identification of Entamoeba histolytica (E. histolytica) by microscopy alone can be problematic because E. dispar and E. moshkovskii are morphologically similar to E. histolytica. Therefore, this study aimed to assess the performance of microscopy in the detection of E. histolytica in stool specimens with the help of PCR-based assays and enzyme-linked immunosorbent assay (ELISA).

Between September, 2017 and September, 2018, 200 stool specimens were obtained from Jordanian patients with suspected amebiasis. All specimens were subjected to microscopic analysis. DNA was extracted from the microscopy-positive stool samples. A conventional PCR and a duplex real-time PCR were performed to detect E. histolytica and E. dispar.

By microscopy, 35% (70/200) of specimens were tested positive for Entamoeba complex. All 70 microscopic-positive Entamoeba complex samples were negative for the presence of E. histolytica by the NOVITEC® E. histolytica ELISA assay. All 70 samples positive by microscopy were negative for the presence of E. histolytica and E. dispar by PCR-based assays.

We suspect some of these microscopy-positive stool specimens might contain a potentially novel species of Entamoeba that could not be detected by ELISA or PCR-based assays specific for E. histolytica and E. dispar. Diagnosis of amebiasis remains challenging here in Jordan and hence highlighting the need for improved diagnostic method.

Amoebiasis diagnosis is usually based on microscopy that cannot differentiate pathogenic E. histolytica from morphologically identical non-pathogenic species. 194 fecal samples were collected from diarrheic &/or dysenteric patients and examined for Entamoeba complex microscopically, E. histolytica/E. dispar coproantigen using ICT and E. histolytica coproantigen using Tech lab E. histolytica II ELISA test. Entamoeba complex trophozoites/cysts, E. histolytica/E. dispar coproantigen and E. histolytica coproantigen were detected in 22.2, 14.4 and 3.6 % of samples, respectively. Microscopy and ICT method had limited sensitivity with poor PPV (9.3 and 7.1 %, respectively) and both slightly agree with ELISA test. The prevalence of E. histolytica was low (3.6 %) in studied individuals and was 14 times lower than non-pathogenic amoebae. E. histolytica detection studied individuals was positively associated with mucoid and bloody stool, which makes them disease predictors. E. histolytica fecal ELISA assay for E. histolytica detection surpassed microscopy and E. histolytica/E. dispar ICT assay. This has highlighted the need for practical non-microscopic detection methods that can differentiate between amoeba infections to avoid unnecessary and possibly harmful therapies and to determine the true prevalence and epidemiology of E. histolytica.

Epidemiological studies on amebiasis have been reassessed since Entamoeba histolytica and E. dispar were first recognized as distinct species. Because the morphological similarity of these species renders microscopic diagnosis unreliable, additional tools are required to discriminate between Entamoeba species. The objectives of our study were to compare microscopy with ELISA kit (IVD®) results, to diagnose E. histolytica infection, and to determine the prevalence of amebiasis in a sample of students from southeastern Brazil.

In this study, diagnosis was based on microscopy due to its capacity for revealing potential cysts/trophozoites and on two commercial kits for antigen detection in stool samples.

For 1,403 samples collected from students aged 6 to 14 years who were living in Divinópolis, Minas Gerais, Brazil, microscopy underestimated the number of individuals infected with E. histolytica/E. dispar (5.7% prevalence) compared with the ELISA kit (IVD®)-based diagnoses (15.7% for E. histolytica/E. dispar). A comparison of the ELISA (IVD®) and light microscopy results returned a 20% sensitivity, 97% specificity, low positive predictive value, and high negative predictive value for microscopy. An ELISA kit (TechLab®) that was specific for E. histolytica detected a 3.1% (43/1403) prevalence for E. histolytica infection.

The ELISA kit (IVD®) can be used as an alternative screening tool. The high prevalence of E. histolytica infection detected in this study warrants the implementation of actions directed toward health promotion and preventive measures.