Dientamoeba fragilisDNA detection inEnterobius vermiculariseggs

Abstract

Dientamoeba fragilis is an intestinal protozoan suspected of causing gastrointestinal symptoms, and its mode of transmission is unknown, although first described almost a century ago. A hypothesis is that Enterobius vermicularis is a vector for D. fragilis, and recently, D. fragilis DNA was detected within surface-sterilized eggs of E. vermicularis. Using real-time PCR, we detected D. fragilis DNA in 18 (85%) of 21 samples of E. vermicularis eggs collected from patients harbouring D. fragilis in faeces. This finding supports the hypothesis that E. vermicularis may have an important role in the transmission of D. fragilis.This paper describes a protocol to wash and surface-sterilize E. vermicularis eggs, with the aim of showing presence of both E. vermicularis and D. fragilis specific DNA within, and the results from 20 co-infected patients. The study has merit as a confirmatory study of the trials by Röser et al. (2013), and includes improvements of the protocol.

Dientamoeba fragilis, One of the Neglected Intestinal Protozoa

“…Studies related to the detection of D. fragilis DNA from the sterilized surface of E. vermicularis eggs, as well as D. fragilis DNA within these eggs, certainly supports the role of E. vermicularis in D. fragilis transmission (5,16). However, the presence of DNA within the eggs is not confirmation that viable D. fragilis organisms were present (5).…”

“…Implication of possible helminth vectors is based on the fact that the organism most closely related to D. fragilis, Histomonas meleagridis, has a helminth vector (15,16). Although a number of reports support this hypothesis of transmission, other reports find no association between helminth vectors and infections with D. fragilis.…”

Dientamoeba fragilis, the Neglected Trichomonad of the Human Bowel

“…Several reports implicate the human pinworm, Enterobius vermicularis, as a probable vector of D. fragilis transmission (72,(153)(154)(155). This is not an unreasonable hypothesis based on the evidence at hand.…”

“…Several theories were proposed to address this problem, the most prominent being that transmission occurred via the ova of a helminth (69,72). Recent advances in D. fragilis cultivation (33,89), animal studies (8,38), microscopic and electron microscopic studies (7), and molecular screening (154,155) have contributed to our current understanding of D. fragilis transmission. However, despite these advances, the mode of transmission employed by D. fragilis remains elusive and is still a topic of debate.…”

“…The role of E. vermicularis as a vector of D. fragilis transmission is supported by two recent studies that detected D. fragilis DNA in DNA extracted from surface-sterilized E. vermicularis ova (154,155). Hypochlorite was used to ensure that the external surfaces of these ova were DNA free prior to DNA extraction (154,155).…”