Molecular epidemiology of Dientamoeba fragilis.

The flagellated protozoan Dientamoeba fragilis is one of the most commonly diagnosed parasite of the human gut, with a global distribution. Nevertheless, essential aspects of its biology remain incompletely understood or controversial, most notably life cycle, host range, transmission routes and the ability to cause disease. Molecular epidemiologic studies are also scarce, and limited by the lack of informative genotyping tools. To date, two D. fragilis genotypes (1 and 2) are recognized, with a strong predominance of genotype 1 in both humans and few animal hosts. Recent studies have shown that a very low level of genetic variability characterizes parasite isolates collected in various geographic areas and from both symptomatic and asymptomatic cases. This has raised the hypothesis D. fragilis may be a clonal organism. The recent availability of transcriptome data should greatly assist the development of markers useful to understand genetic diversity of D. fragilis at the population level.