ABSTRACT
BACKGROUND: Blastocystis 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. METHODS: A 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. RESULTS: Endolimax 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%). CONCLUSIONS: DNA 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.
Subject(s)
Blastocystis Infections/epidemiology , Blastocystis Infections/parasitology , Blastocystis/isolation & purification , Genetic Variation , Phylogeny , Urban Population , Adolescent , Adult , Aged , Aged, 80 and over , Blastocystis/classification , Blastocystis/genetics , Brazil/epidemiology , Child , Child, Preschool , DNA Primers , DNA, Protozoan/genetics , DNA, Ribosomal/genetics , Feces/parasitology , Female , Humans , Infant , Male , Middle Aged , Polymerase Chain Reaction , Prevalence , Sequence Analysis, DNA , Young AdultABSTRACT
INTRODUCTION: This study evaluated the frequency of intestinal parasites, emphasizing the identification and differentiation of Entamoeba spp. METHODS: Multiplex polymerase chain reaction (PCR), coproantigen tests and morphometric analysis were performed for Entamoeba spp. differentiation. RESULTS: The overall frequency of intestinal parasites was 65%. Entamoeba histolytica was detected by the coproantigen test, and the PCR showed that Entamoeba dispar predominated in the population. In contrast, morphometric analysis was important for identifying Entamoeba hartmanni. CONCLUSIONS: It is possible to identify the causative agent of amoebiasis and to differentiate this agent from other species by combining techniques.
