Prevalence of Entamoeba histolytica in patients with schistosomal colonic polyposis.

Two hundred and fifty-seven Egyptian patients were classified into three groups: patients with schistosomal colonic polyposis, those with simple schistosomiasis without polyposis, and a non-schistosomal group. A diagnosis of schistosomiasis was made by clinical history and examination plus three fresh stool examinations or a rectal biopsy. The presence of schistosomal colonic polyps was established by sigmoidoscopy and biopsy of polyps. Stool examinations were made on all individuals, using the merthiolate-iodine-formaldehyde technique to detect Entamoeba histolytica. We found the prevalence of amebiasis in the group with schistosomal colonic polyposis (37%) to be significantly higher than that in the non-schistosomal group (11%) and in the schistosomal group without polyposis (15%). The difference in prevalence of amebiasis between the simple schistosomal and non-schistosomal groups was not significant.