Subtype analysis of Blastocystis isolates in Swedish patients.
ABSTRACT Blastocystis is a genetically diverse and widespread intestinal parasite of animals and humans with controversial pathogenic potential. At least nine subtypes of Blastocystis have been found in humans. The genetic diversity of Blastocystis was examined in stool samples from 68 patients from the Stockholm area, Sweden. Blastocystis was identified by light microscopy, and subtyped by sequencing the 5'-end of the small subunit ribosomal RNA gene. Five Blastocystis subtypes were identified in the 63 patients whose samples were successfully subtyped: ST1 (15.9%), ST2 (14.3%), ST3 (47.6%), ST4 (20.6%), and ST7 (1.6%). ST3 was more common in males compared to females (P=0.049). Comparative molecular analysis of Blastocystis sequences revealed intra-subtype variations within the identified subtypes with the exception of ST4. Among ST4 sequences in this study, as well as in the majority of human GenBank sequences, a limited genetic diversity was found compared to what was found among the other common subtypes (ST1, ST2 and ST3). The relative prevalence of ST4 in this study was comparable to the overall distribution of ST4 in European cohorts (16.5%). This contrasts with the sparse reports of ST4 in studies from other continents, which may indicate that the distribution of this subtype is geographically heterogeneous.
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ABSTRACT: Blastocystis hominis is a gastrointestinal tract parasite whose pathogenic role, and zoonotic potential remains unclear. Several microorganisms similar to B. hominis have been reported in a variety of non-human hosts, and described as Blastocystis spp. The study aimed to verify the occurrence of Blastocystis spp. in three species of poultry of two municipal markets, by observing the microorganisms' forms in stool samples stained with Giemsa. A total of 214 birds, distributed into two markets, were studied. In each of the markets were observed, 35 ducks (Anas platyrhynchos), 35 Japanese quail (Coturnix japonica) and 35 chicks (Gallus gallus). In market A, 8 (22.9%) chicks, 15 (42.9%) quails and 13 (37.1%) and ducks were diagnosed with Blastocystis spp.; in market B, 15 (42.9%) chicks, 2 (5.56%) quails, and 21 (55.3%) ducks. A significant difference was observed only between quails from the two markets but no statistical difference was observed when all infected birds in the two markets were compared. In stool samples positive with Blastocystis spp. and stained with Giemsa were observed forms as vacuolar, granular, amoeboid, and cystic, and some types of reproduction, such as binary fission, plasmotomy and budding. Both markets had unhygienic conditions of animal facilities, favoring the infection among them.
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ABSTRACT: Blastocystis is a genetically diverse and a common intestinal parasite of humans with a controversial pathogenic potential. This study was carried out to identify the Blastocystis subtypes and their association with demographic and socioeconomic factors among outpatients living in Sebha city, Libya. Blastocystis in stool samples were cultured followed by isolation, PCR amplification of a partial SSU rDNA gene, cloning, and sequencing. The DNA sequences of isolated clones showed 98.3% to 100% identity with the reference Blastocystis isolates from the Genbank. Multiple sequence alignment showed polymorphism from one to seven base substitution and/or insertion/deletion in several groups of non-identical nucleotides clones. Phylogenetic analysis revealed three assemblage subtypes (ST) with ST1 as the most prevalent (51.1%) followed by ST2 (24.4%), ST3 (17.8%) and mixed infections of two concurrent subtypes (6.7%). ST1 infection was significantly associated with female (P = 0.009) and low educational level (P = 0.034). ST2 was also significantly associated with low educational level (P= 0.008) and ST3 with diarrhoea (P = 0.008). Phylogenetic analysis of Libyan Blastocystis isolates identified three different subtypes; with ST1 being the predominant subtype and its infection was significantly associated with female gender and low educational level. More extensive studies are needed in order to relate each Blastocystis subtype with clinical symptoms and potential transmission sources in this community.PLoS ONE 01/2013; 8(12):e84372. · 3.53 Impact Factor
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ABSTRACT: Blastocystis sp. is currently the most common intestinal protist found in human feces and considered an emerging parasite with a worldwide distribution. Because of its potential impact in public health, we reinforced the picture of Blastocystis sp. prevalence and molecular subtype distribution in Africa by performing the first survey of this parasite in Senegal. Stool samples from 93 symptomatic presenting with various gastrointestinal disorders or asymptomatic children living in three villages of the Senegal River Basin were tested for the presence of Blastocystis sp. by non-quantitative and quantitative PCR using primer pairs targeting the SSU rDNA gene. Positive samples were subtyped to investigate the frequency of Blastocystis sp. subtypes in our cohort and the distribution of subtypes in the symptomatic and asymptomatic groups of children. By the use of molecular tools, all 93 samples were found to be positive for Blastocystis sp. indicating a striking parasite prevalence of 100%. Mixed infections by two or three subtypes were identified in eight individuals. Among a total of 103 subtyped isolates, subtype 3 was most abundant (49.5%) followed by subtype 1 (28.2%), subtype 2 (20.4%) and subtype 4 (1.9%). Subtype 3 was dominant in the symptomatic group while subtypes 1 and 2 were detected with equal frequency in both symptomatic and asymptomatic groups. The distribution of subtypes was compared with those available in other African countries and worldwide. Comparison confirmed that subtype 4 is much less frequently detected or absent in Africa while it is commonly found in Europe. Potential sources of Blastocystis sp. infection including human-to-human, zoonotic, and waterborne transmissions were also discussed. The prevalence of Blastocystis sp. in our Senegalese population was the highest prevalence ever recovered worldwide for this parasite by reaching 100%. All cases were caused by subtypes 1, 2, 3 and 4 with a predominance of subtype 3. More than half of the children infected by Blastocystis sp. presented various gastrointestinal disorders. Such high prevalence of blastocystosis in developing countries makes its control a real challenge for public health authorities.BMC Infectious Diseases 03/2014; 14(1):164. · 3.03 Impact Factor