Use of Real-Time Polymerase Chain Reaction to Differentiate between Pathogenic Entamoeba histolytica and the Nonpathogenic Entamoeba dispar in Ecuador

Abstract

Microscopic examination of stool samples has been considered to be the "gold standard" for diagnosis of intestinal parasites. Recently, polymerase chain reaction (PCR) has been approved by the World Health Organization as the method of choice for the diagnosis of <i>Entamoeba histolytica</i>. Of the 106 stool samples collected from the Esmeraldas and Pichincha provinces of Ecuador, all (100%) were positive for <i>E. histolytica</i>/<i>Entamoeba dispar</i> by light microscopy, whereas using real-time PCR (RT-PCR) DNA amplification, 74 (69.8%) were positive for <i>E. dispar</i> and only three (2.8%) were positive for <i>E. histolytica</i>. Some 29 (27.4%) samples were negative for the presence of either <i>E. histolytica</i> or <i>E. dispar</i>, this may be due the presence of <i>Entamoeba mosksvskii</i>, which is morphologically identical to <i>E. histolytica</i>/<i>E. dispar</i> and not specifically targeted by the RT-PCR used. These results indicate the necessity of reevaluating the epidemiology of amebiasis in Ecuador as the prominent species found are nonpathogenic.