Microscopic technique is still frequently practiced in many parasitology diagnostic laboratories, particularly in developing countries for the identification of E. histolytica/E. dispar and include wet preparation, concentration, and permanently stained smears (Fotedar et al. 2007).
However, several studies suggested that microscopy is labor-intensive, time-exhaustion, needs technician's experience, and sensitivity is low (Vanathy et al. 2017).
In addition, examination of three stool samples over not more than 10 days is recommended to increase the sensitivity of microscopy, as these organisms may be shedded intermittently (Varghese et al. 2021).
So, Immunochromatographic tests were designed to provide a solution to overcome these disadvantages and allow the detection of Entamoeba copro-antigen (Saad et al. 2015).
In the present study, the microscopic examination revealed that the prevalence of E. histolytica/dispar was 43% in participated patients. This was more or less close to those reported in Egypt; 40.77% among 130 patients complaining of chronic abdominal pain in Sohag (Omran and Mohammed 2015) and 44.4% out of 230 primary school children in Sharkia (Hussein et al. 2021).
While the prevalence of study was lower than 56% among 50 hemodialysis patients in Sohag University Hospitals (EL-Nadi and Taha 2004). This may be due to our study patients were immunocompetent.
On the other hand, the prevalence of study was higher than 8.3% out of 300 children in Assuit (Dyab et al. 2016), 13% among school children and 23.5% among 100 random fecal samples using the mini-FLOTAC in Sohag (EL-Nadi et al. 2017; EL-Nadi et al. 2019). This could be explained by the fact that our study conducted on symptomatic patients.
The present study showed the highest prevalence was observed among the age group less than 20 years (58.14%), followed by patients between 20–40 years (34.88%) and patients > 40–60 years (6.98%) however it revealed no significant relationship between age and the infection (P value = 0.344). The result agreed with El-Nadi et al. (2017) in Sohag and ESlam et al. (2017) in Libya who revealed that there was no significant correlation between the infection and age groups in school children (P < 0.425, P < 0.081 respectively). However, the result disagreed with a study by Hegazi et al. (2013) who found that the prevalence of the infection among infants under one year in Saudi Arabia was statistically significant (P value < 0.02) due to inadequate breastfeeding and bottle-feeding practices among cases.
The present study revealed E. histolytica/dispar infection among female patients (58.14%) was higher than males (41.86%), however, no significant association was found between the gender and the infection (P value < 0.471). This agreed with the study by El-Nadi et al. (2017) in Sohag who showed no statistically significant differences regarding gender (P value < 0.446). However, these results differed from the results by ESlam et al. (2017) who reported boys (6%) were significantly more infected with E. histolytica/dispar than girls (3%) in school children in Libya (P value < 0.05). This could be explained by the fact that boys were commonly affected because they were fully independent in using toilet and were more involved in outdoor activities.
In the present study, Patients in rural areas (83.72%) were at higher risk for E. histolytica/dispar infection than those living in urban areas (16.28%) and there was a significant association between the prevalence and residence (P value < 0.036). Also, Khan et al. (2019) in Pakistan reported that the prevalence of the infection among participants in rural areas was significantly higher than urban areas (P value < 0.05). However, Atia et al. (2016) in Zagazig, Egypt found that the prevalence of the infection was higher in patients living in rural areas, but without significant difference (p > 0.05).The high percentage of intestinal protozoan infections in rural areas may be due to poverty, poor living and hygienic conditions, drinking of underground water which is contaminated with sewage, compared to urban areas, also the extensive use of human and animal excreta as fertilizer in agriculture, the household wastewater is thrown in irrigation channels in addition to the close contact with animals (Pham-Duc et al. 2011).
In the present study, the patients from large households with family sizes of 5 members or more (81.4%) showed a significantly higher prevalence of the infection than those from smaller families (18.6%). Family size was a significant risk factor associated with the infection (P value = 0.03). The same results were met with the study by El-Nadi et al (2017) in Sohag who showed that intestinal parasitic infections among school children were significantly higher with large family sizes of more than 5 members compared with smaller families (P value < 0.006).
In the present study, the sensitivity, specificity, PPV, & NPV of the Rida®Quick Entamoeba test was 97.67%, 96.49%, 95.45% and 98.21% respectively with no cross-reactivity with other intestinal parasites. This agreed with Saad et al. (2015) who revealed sensitivity (100%) and specificity (97.4%) in addition to Atia et al. (2016) who reported sensitivity (100%) and specificity (100%). As these studies compared the ICT with microscopy in detection of the parasites in stool samples.
However, these results disagreed with a study by Goñi et al. (2012) who reported lower results in detection of E histolytica where sensitivity was 62.5% and specificity was 96.1% which might be due to the fact that they used PCR as standard reference. Also, Abu Sheishaa, (2021) found lower sensitivity (80.0%) and specificity (88%) as they used ELIZA as standard reference.
The false-negative samples may be attributed to the presence of low parasite numbers, which leads to a drop in the antigen levels below the detection limit of the rapid methods (Garcia et al.2003; Weitzel et al. 2006).
On the other hand, the false-positive samples may be due to intermittent parasite excretion in the stool or due to persistent antigen in recently cured cases (Shimelis and Tadesse 2014).
The limitations of the ICT test were high cost and inability to differentiate between the pathogenic E. histolytica and non-pathogenic E. dispar. Moreover, quantitative ICT models are required to measure the intensity of infection and monitor therapeutic success.