Pathogenic Entamoeba histolytica--a rare incidence in persons microscopically positive for cysts in faeces

In the Czech Republic, 40 to 50 cases of Entamoeba histolytica/dispar infections are reported annually to the National Reference Laboratory for diagnostics of intestinal parasitoses. However, the actual number of patients with Entamoeba histolytica infection is unknown as diagnosis relies on cyst detection in faecal samples by microscopy, the method which cannot differentiate between pathogenic E. histolytica and nonpathogenic E. dispar. The aim of this study was (1) to evaluate the proportions between E.histolytica and E. dispar in patients, mainly travellers, using multiplex nested PCR technique, (2) to evaluate specificity of the technique for detection of these species. Faecal samples from 68 patients microscopically positive for cysts of E. histolytica/dispar were tested by PCR. Of these, 65 persons (95.6%) were positive for E. dispar, whereas only 3 patients (4.4%) were positive for E. histolytica. This study shows that the number of patients infected with pathogenic E. histolytica is very low in the Czech Republic and points to the necessity of differentiation of Entamoeba species for physician's decision in treatment of E. histolvtica- or E.dispar-infected persons.