Abstract
Blastocystis spp. is one of the most common protozoa of humans and animals worldwide. The genetic diversity of Blastocystis spp. might be associated with a wide range of symptoms. However, the prevalence of each subtype is different in each country. Until now, there is no standard method for subtyping of Blastocystis spp. We developed a sequential restriction fragment length polymorphism (RFLP) analysis for the rapid differentiation of human Blastocystis subtypes. A large-scale study was also conducted to determine the subtype distribution of Blastocystis spp. in Thailand. Stool samples were collected from 1025 school-age students in four regions of Thailand. Blastocystis infections were identified by direct smear, formalin ethyl-acetate concentration technique (FECT), Boeck and Drbohlav’s Locke-Egg-Serum (LES) medium culture, and polymerase chain reaction (PCR) of small-subunit ribosomal DNA (SSU rDNA). Subtypes of Blastocystis spp. were determined by RFLP. Phylogenetic tree of partial SSU rDNA sequences of Blastocystis spp. was constructed using the Maximum Likelihood (ML) method. Out of 1025 students, 416 (40.6%) were positive for Blastocystis spp. Using two steps of RFLP reactions, we could determine subtype one–three among these students. Subtype 3 was the most common subtype (58.72%) in Thai students, followed by subtype 1 (31.2%), and subtype 2 (10.1%). Blastocystis subtype 3 was the most prevalent in all regions of Thailand. The subtype distribution of Blastocystis spp. in Thailand was different from other countries.
Highlights
Blastocystis spp. is a common enteric protozoan in human and animals worldwide
To determine genetic diversity of Blastocystis spp., 480 bp of SSU rDNA fragments were successfully amplified with the Blast 505-532
We reported a high prevalence of Blastocystis spp. (40.6%) in school-age
Summary
Blastocystis spp. is a common enteric protozoan in human and animals worldwide. Little is currently known about the biology of Blastocystis spp. Taxonomy, life cycle, mode of transmission, as well as treatment management of the Blastocystis infection remains unclear. Conflicting studies or reports concerning the pathogenicity of the protozoan continue to be published. Blastocystis spp. was thought to be pathogenic only in immunocompromised patients [1]. The public health significance of Blastocystis infection has increased in the last decade. Blastocystis infection causes various symptoms in immunocompetent individuals in the absence of any parasitic co-infection [2,3]. Prevalence of Blastocystis infection is about 1%–23% in developed countries [4,5], Pathogens 2019, 8, 38; doi:10.3390/pathogens8010038 www.mdpi.com/journal/pathogens
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