Molecular detection and identification of Enteromonas species in human and animal hosts using polymerase chain reaction and DNA sequencing

Enteromonas hominis, a human intestinal protozoan parasite of the diplomonad group, has been overlooked because of its commensal features; therefore, molecular studies on this parasite are limited. To address this gap, we designed a molecular screening protocol using polymerase chain reaction (PCR) and DNA sequencing targeting the 18S small subunit ribosomal RNA gene and applied this screening method to the molecular epidemiological analysis of Enteromonas spp. in humans and various livestock. We validated our methodology using stool samples collected from 215 humans and 270 animal hosts (buffaloes, pigs, dogs, goats, horses, rodents, chickens, and ducks) during an annual epidemiological investigation conducted from 2013 to 2016 on Sumba Island, Indonesia. The overall prevalences of Enteromonas spp. were 33.9 % (n = 73/215) in humans and 25.2 % (n = 68/270) in mammals and avians. The positive predictive value of this PCR method for Enteromonas spp., as evaluated through sequencing, was 90.1 % in human samples and 58.1 % in non-human samples (particularly low, 11.4 % in rodents). Although the specificity of the PCR approach may not be perfect, in combination with DNA sequencing, it was effective in detecting and identifying a partial sequence (1458 bp) of the target gene region in Enteromonas species.