The study was carried out over a three-month period (1 June-30 August, 2001) among the pediatric inpatients of Dr. R.M.L. hospital, New Delhi. All the patients satisfying the inclusion criteria were included in the study.

Inclusion criteria. Less than 5 year of age and acute watery diarrhea of less than 72-hour duration.

Exclusion criteria. Dysentery, mucoid diarrhea, and history of receiving any antiparasitic drug in the ten days prior to admission. Age and sex-matched controls were selected from among the hospital in-patients, provided they had not had diarrhea in the previous month and, had not received any antiparasitic drug in the last ten days. Information regarding age, sex, place of residence and source of water supply was obtained in a proforma. From each case and control, at least (approx.) 5 mL or 5 g of faeces was collected in a clean, sterile container, marked and dispatched by hand to the pathology laboratory. These samples were examined by one of the authors (RBY) within 30 minutes of collection. Both direct and concentration methods were used to examine the specimen for parasitic ova, blood cell, trophozoites and cysts. Definition of acute diarrhea and dysentery, indications for admission and the treatment protocols used were as per the standard guidelines(2). Mucoid diarrhea was defined as an episode with the presence of mucus in a loose stool (without any visible blood) throughout the entire duration of diarrhea, either reported by parents or noted on microscopic examination. Stool examination was not done on Sundays and public holidays, and after 3 p.m. on weekdays due to administrative constraints. An informed verbal consent was obtained from parents or caregivers of all cases and controls. Ninety-two of the control group parents and none of the cases refused consent. Significance of differences in proportions was assessed by c2 test using a 5% level of significance as cut-off.

A total of 156 patients and 156 controls were investigated. Age, sex, place of residence and source of water supply were not significantly different between the two groups. Only two children (1.3%) in the study group had evidence of acute infection with E.histolytica (one of these had 4-6 RBC/hpf on microscopy) whereas 12 (7.7%) had cysts of the same organism. In the control group, 14 (8.97%) of the children were cyst-passers whereas none had the presence of trophozoites of E. histolytica in stool. Ascaris ova were found in 5 (3.2%) and 2 (1.3%) children and G.lamblia cysts in 3 (1.9%) and 4 (2.6%) children respectively, in the study and control group. On statistical analysis, no significant difference was found between the two groups with respect to E. histolytica cyst passage or trophozoites in stool.

Previous studies of hospitalized outpatient children with acute diarrhea from developing countries have reported the prevalence of this organism to vary from nil to 4.9%(4-8). However, prevalence rates of 4-6% in control children have also been reported(4,9). None of the 402 under-3 children with diarrhea in Pakistan had evidence of E. histolytica infection as compared to 3.7% of the controls (4). Out of 265 under-5 inpatients with acute diarrhea in Jordan, only 4.9% had evidence of E.histolytica infection(5). 2.6% of 152 cases of acute childhood diarrhea in Calcutta were reported to have evidence of E.histolytica infection(6) as compared to only 0.5% and 0.6% of under 5 children with diarrhea in Nigeria and Dhaka, respectively(7,8). The report by Shetty et al has been one of the few reports implicating E.histolytica as a significant cause of diarrhea in children. In 361 pediatric in-patients with acute diarrhea, E.histolytica prevalence upto 20.3% (in 7-12 month age group) were reported(10).

However, on the basis of majority of the published studies, E.histolytica is an uncommon cause of acute diarrhea in under five children. Our findings also revalidate previous reports. Further, although stool microscopy was used for diagnosis in the study protocol, on retrospect stool microscopy results would not have contributed to change in therapeutics decision in 155 of the 156 children. We, therefore, wish to reiterate that stool microscopy and antiprotozoal agents do not have any role in the management of under-five children with acute watery diarrhea.