DNA of Dientamoeba fragilis detected within surface-sterilized eggs of Enterobius vermicularis. Exp Parasitol

Laboratory of Parasitology, Department of Microbiology and Infection Control, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark. Electronic address: .
Experimental Parasitology (Impact Factor: 1.64). 10/2012; 133(1). DOI: 10.1016/j.exppara.2012.10.009
Source: PubMed


With no evidence of a cyst stage, the mode of transmission of Dientamoeba fragilis, an intestinal protozoon of common occurrence and suggested pathogenicity, is incompletely known. Numerous studies have suggested that eggs of intestinal nematodes, primarily Enterobius vermicularis (pinworm), can serve as vectors for D. fragilis, although attempts to culture D. fragilis from pinworm eggs have been unsuccessful and data from epidemiological studies on D. fragilis/pinworm co-infection have been conflicting. The aim of this study was to investigate whether we could detect D. fragilis DNA from pinworm eggs collected from routine diagnostic samples (cellophane tape) and surface-sterilised by hypochlorite. DNA was extracted from individual eggs and tested by PCR using D. fragilis- and E. vermicularis-specific primers; amplicons were sequenced for confirmation. In cellophane tape samples from 64 patients with unknown D. fragilis status we detected D. fragilis DNA in 12/238 (5%) eggs, and in a patient known to harbour D. fragilis we detected D. fragilis DNA in 39/99 (39%) eggs. The finding of D. fragilis DNA within eggs of E. vermicularis strongly supports the hypothesis of D. fragilis-transmission by pinworm and has implications for antimicrobial intervention as well as control and public health measures.

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Available from: Dennis Röser, Mar 03, 2015
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    • "Recently, Roser et al. (2013) have detected D. fragilis DNA inside E. vermicularis eggs agreeing with the prediction of Dobell in 1940 [48]. While many reports of a higher than anticipated rate of coinfection between D. fragilis and E. vermicularis led researchers to postulate E. vermicularis as the probable vector responsible for its transmission [48] [49], other groups have proved no coinfections with D. fragilis and other worms, suggesting fecal-oral transmission as the possible mechanism of transmission of D. fragilis [9] [10]. A new study by Munasinghe et al. (2013) using rodents and mice infected with human isolates reported the discovery of a new cyst stage in the life cycle of D. fragilis strongly suggesting oral–fecal transmission as the possible route of infection [23]. "
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    ABSTRACT: Dientamoeba fragilis is an enteric protozoan parasite that remains neglected, probably due to the misconception that it is uncommon and non-pathogenic. As more information be‐ came available and antimicrobial agents were developed with activity against this para‐ site, it became clear that D. fragilis is responsible of an active infection, associated with symptoms such as abdominal pain and diarrhea. The clinical presentation of dientamoe‐ biasis varies from asymptomatic carriage to symptoms ranging from altered bowel mo‐ tions, abdominal discomfort, nausea and diarrhea with associated eosinophilia reported in up to 50% of paediatric and 10% of adult patients. Moreover, controversy exists over the protective role of the parasite in priming the immune system in a beneficial way such as in selecting beneficial bacteria, keeping potential harmful microbial intruders at bay or producing metabolites beneficial to the host. Thus, a number of ambiguities and obscuri‐ ties surrounding D. fragilis infections exist. Moreover, the means by which this parasite is transmitted has not been fully defined. The diagnostic recognition of this parasite in fecal examinations requires specific processing and expertise; thus, it is possible that many in‐ fections with D. fragilis may go undiagnosed. A number of studies conducted on small numbers of case reports have demonstrated parasite clearance, as well as resolution of clinical symptoms following treatment with various antiparasitic compounds such as pa‐ romomycin, hydroxyquinolines and the 5-nitroimidazoles, including metronidazole and tinidazole. In addition there is very little in vitro susceptibility data available for the or‐ ganism making some current treatment options questionable. This chapter reviews the scientific literature relating to Dientamoeba's life cycle, prevalence, diagnosis and patho‐ genicity.
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    • "As the ingestion of a small number of E. vermicularis eggs can cause infection, the fact that those children who had the most eggs on their hands did not wash their hands before eating , means that the potential for infection is great, and that hand washing promotion in these communities could have an impact on infection levels in children. In addition E. vermicularis eggs have recently been identified as vectors for Dientamoeba fragilis (Ogren et al., 2013; Roser et al., 2013), a gastrointestinal parasite that has been suggested to be pathogenic. Therefore by decreasing infection of E. vermicularis, disease, such as chronic diarrhoea, fatigue, and stunted development in children, caused by D. fragilis will also be decreased. "
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    ABSTRACT: Enterobius vermicularis is a helminth that is difficult to control, is found globally, especially in crowded conditions, and can be transmitted from person to person by contaminated hands. A newly developed method for the quantification of helminth eggs on hands was tested among schoolchildren in a rural South African region to look at the role hands play in helminth infection, and to determine the risk factors for hand contamination. The study found 16.6% of participants' hands positive for helminth eggs, with E. vermicularis most commonly identified. Egg concentrations on hands ranged from 0-57 eggs/2 hands. Gender, toilet type used at home, and not reporting to wash hands with soap before eating were all associated with the presence of eggs on hands. The study highlights the need to improve sanitation facilities, and promote handwashing with soap in schools to prevent transmission of E. vermicularis. Copyright © 2015. Published by Elsevier B.V.
    No preview · Article · Jul 2015 · Acta tropica
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    • "Les protozooses cavitaires ne génèrent pas d'HE; le cas du parasitisme à Dientamoeba fragilis, souvent retrouvé associé à cette anomalie hématologique , serait expliqué par la fréquente association avec l'oxyurose [15]. Cette coïnfection serait elle-même favorisée par une transmission transovarienne de D. fragilis par Enterobius vermicularis [16]. Une HE est par contre observée lors de certaines protozooses systémiques rares, comme la sarcocystose [17]. "
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    ABSTRACT: Hypereosinophilia (HE) is defined by an increase of more than 0.5 G/L eosinophils in circulating blood. This haematological abnormality may have multiple etiologies but the majority of them correspond to a secondary HE known as “allergic HE”, encountered frequently in helminth infections. Indeed, during an aggression caused by helminths, cytokines called “alarmins” are secreted and they lead to an overproduction of IL-5, IL-13 and IL-4, which are accountable for HE and increase of type E immunoglobulin. High level of eosinophils evolving over a long period may lead to tissue damage in relation to the activation of these cells, leading to severe clinical manifestations. Exploring an HE requires anamnestic, epidemiological, and clinical data to orientate the diagnosis and also to target the panel of laboratory tests. Optical techniques remain the first line of investigation, because these tests can quickly lead to the definitive diagnosis, if performed by experienced operators. Immunodiagnostics of helminth infections present a major contribution in special situations, but these techniques are complementary to conventional optical investigations and are often difficult to explore.
    Full-text · Article · Apr 2014 · Revue Francophone des Laboratoires
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