Abstract
BackgroundBlastocystis is a cosmopolitan protist parasite found in the human gastrointestinal tract and is highly prevalent in developing countries. Recent molecular studies have revealed extensive genetic diversity, which has been classified into different subtypes (STs) based on sequence analysis of small subunit ribosomal RNA gene. Blastocystis is one of the most common fecal parasites in Brazil, but the diversity of subtypes remains unknown in the country. This study aimed to determine the distribution of Blastocystis STs in an urban community in Duque de Caxias, Rio de Janeiro, Brazil.MethodsA total of 64 stool samples positive for Blastocystis in Pavlova’s medium were subtyped by PCR and sequenced using primers targeting the small subunit rRNA gene, in addition to phylogenetic analysis and subtype-specific PCR using sequence-tagged-site (STS) primers.ResultsEndolimax nana (14%), Entamoeba complex (10.5%), Taenia sp. (0.6%), Trichuris trichiura (1.3%) and Enterobius vermicularis (1.3%) were detected in Blastocystis-positive samples. Of the 64 samples tested by PCR/DNA sequencing, 55 were identified as ST1 (42%), ST3 (49%), ST2 (7%) and ST4 (2%), and the presence of mixed ST (ST1 + ST3) infection was detected in nine samples (14%).ConclusionsDNA sequencing and phylogenetic analysis of Brazilian Blastocystis isolates identified four different subtypes. To our knowledge, this study provided the first genetic characterization of Blastocystis subtypes in an urban area of Rio de Janeiro, Brazil. We also identified ST4 for the first time in Brazil. Further studies are necessary to determine the distribution of STs across human populations in Rio de Janeiro.
Highlights
Blastocystis is a cosmopolitan protist parasite found in the human gastrointestinal tract and is highly prevalent in developing countries
Blastocystis spp. are strictly anaerobic unicellular organisms that inhabit the gastrointestinal tract of humans as well as other mammals, birds, amphibians, reptiles, fish, arthropods and annelids [1,2,3,4,5,6,7,8,9]
These findings provide strong evidence of the ability of Blastocystis to migrate to extraintestinal sites and of its pathogenic potential
Summary
Blastocystis is a cosmopolitan protist parasite found in the human gastrointestinal tract and is highly prevalent in developing countries. Blastocystis is one of the most common fecal parasites in Brazil, but the diversity of subtypes remains unknown in the country. One case of enteroinvasive blastocystosis diagnosed by histopathological analysis of biopsies showed Blastocystis in ulcers in the cecum, transverse colon and rectum of an immunocompetent individual, indicating that the parasite has invasive potential [29]. Several studies suggest an association of Blastocystis with urticaria and skin lesions in immunocompetent individuals [34, 35]. These findings provide strong evidence of the ability of Blastocystis to migrate to extraintestinal sites and of its pathogenic potential. Some epidemiological surveys have suggested a strong association between irritable bowel syndrome (IBS) and Blastocystis, but this association has been questioned [36, 37]
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