Prevalence of Entamoeba histolytica and Entamoeba dispar in Gon¬bad City, 2006, Iran

Background: Differential diagnosis of two protozoan parasites Entamoeba histolytica and E. dispar is of great clinical and epide¬miologi¬cal importance, but except in the case of haematophagous trophozoites in acute dysentery, it is not possible to differ¬entiate them by microscopy. The present study was carried out from February 2005 to July 2006 in order to determine the preva¬lence of E. histolytica and E. dispar in Gonbad City, by using a PCR method. Methods: Five hundred and sixty four fecal samples were collected from primary health care centers of Gonbad both urban and rural ar¬eas. The stool specimens were examined by light microscopy (Direct slide smear, Iodine wet mount, Formal-ether concentra¬tion and Trichrome staining) to distinguish E. histolytica/E. dispar complex and differentiate them from other non-patho¬genic intestinal amoebae. Results: The microscopy results of stool exams showed a frequency rate of 23 positive samples (4.07%) for cyst of E. histo¬lytica/E. dis¬par complex. All the microscopy positive isolates appeared to be infected with cyst of E. histolytica/E. dispar com¬plex were cultivated and maintained successfully in HSr + s medium for DNA extraction and identification by the PCR method. The PCR study showed that 16 isolates (69.56 %) of the Entamoeba samples were E. dispar while 7 samples (30.43%) of those microscopy positive samples were not amplified and none of them showed E. histolytica pattern. Conclusion: High frequency rate of E. dispar in this study were in high agreement with the estimation rate of these entamoe¬bas worldwide.