Molecular epidemiology of human Blastocystis isolates in France
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Blastocystis sp. is the most common eukaryotic parasite in the intestinal tract of humans. Due to its strong impact in public health, in this study, we determined the frequency of different Blastocystis subtypes in patients in France. We hypothesized on the mode of transmission and tested a possible relationship between the subtype and symptomatic status. We obtained a total of 40 stool samples identified as positive for Blastocystis by microscopic examination of smears. Participants consisted of 25 symptomatic and 15 asymptomatic patients, for whom clinical and parasitological data were collected. For nested-polymerase chain reaction and genotyping, DNA was extracted directly from fecal samples or from fecal cultures. Morphological forms observed in fecal cultures were uncorrelated with symptomatic status. Genotyping using partial small subunit rRNA gene analysis identified a total of 43 Blastocystis isolates corresponding to 37 single infections and three mixed infections by two different subtypes. These 43 isolates belonged to five subtypes (1, 2, 3, 4, and 7) with predominance of subtype 3 (53.5%). Patient symptomatic status was uncorrelated with Blastocystis subtype.
This work was developed in the framework of EA3609 scientific program (French Ministry of Research) and supported by the Institut Pasteur de Lille, the Institut National de la Santé et de la Recherche Médicale, the Centre National de la Recherche Scientifique, and the Université Lille Nord de France. The authors thank Jean-Michel Dewitte, Agnès Perus, and Emmanuel Dutoit from the Centre Hospitalier Régional Universitaire de Lille for their help in collecting stool samples and microscopic identification of Blastocystis.
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