Evaluation of a PCR Method for Detection of Entamoeba polecki, with an Overview of Its Molecular Epidemiology

Abstract

<i>Entamoeba</i><i>polecki</i> is a parasite of human and nonhuman primates, other mammals, and birds. Due to overlapping morphological features, cysts of <i>E. polecki</i> may be confused with those of other <i>Entamoeba</i> species commonly found in human fecal samples, including immature cysts of <i>Entamoeba histolytica</i> Although the presence of <i>E. polecki</i> in human <i>Entamoeba</i>-positive stool samples may be rare, its prevalence is likely underestimated due to such confusion. Here, we give examples of diagnostic approaches applied so far and summarize data on the molecular epidemiology of <i>E. polecki</i>, including host specificity and phylogeography. Moreover, we evaluate a novel diagnostic conventional PCR developed for the screening of fecal samples for <i>E. polecki</i> The assay was highly sensitive and specific when used on genomic DNA extracted directly from stool and Swedish wastewater samples. The PCR enabled the identification of all four subtypes (ST1 to ST4) of <i>E. polecki</i> by PCR product sequencing. Most (23/28) subtyped <i>E. polecki-</i>positive samples detected in patients in Sweden between 2002 and 2015 reflected colonization by ST4 and were seen in travelers/foreigners. Two and three human cases of ST2 and ST3, respectively, were also detected. Subtypes 1, 2, and 3 were detected in 3/21 wastewater samples, suggesting local endemicity of these <i>E. polecki</i> subtypes; interestingly, ST4 was not detected in wastewater. In conclusion, the current PCR assay enables simple and cost-effective screening of fecal and wastewater samples for <i>E. polecki</i> Human cases of <i>E. polecki</i> appear to involve primarily ST4, while <i>E. polecki</i> detected in wastewater may be primarily of animal origin.