Department of Environmental and Forest Biology, SUNY-ESF, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA.
Parasitol Res. 2010 Mar;106(4):827-32. doi: 10.1007/s00436-010-1739-8. Epub 2010 Feb 2.
The association of Blastocystis species infections with gastrointestinal symptoms in humans is clouded by the variable presentation of disease and multiple lineages of the parasite that can infect humans and other animals. It has long been suspected that certain subtypes of Blastocystis may be more or less pathogenic, be restricted to certain hosts, or have limits to their geographic distribution. In the state of Oregon, USA, Blastocystis spp. are the most commonly encountered parasites in fecal specimens submitted for diagnostic evaluation, yet the diversity of subtypes is unknown. In this study, fecal samples were collected from individuals experiencing symptoms associated with blastocystosis and analyzed by polymerase chain reaction for presence of the parasite and DNA sequenced for subtyping. Five of 19 individuals tested positive for the parasite, all of which were also positive by previous ova and parasitology examination. DNA sequencing of the small subunit ribosomal DNA and elongation factor 1 alpha gene followed by phylogenetic subtyping identified five unique subtypes, representing Blastocystis subtypes 1, 2, 3, 4, and 8. No symptoms were consistently associated with presence or absence of infection, although abdominal pain and fatigue were reported by all infected individuals. Multiple subtypes are indicative of multiple sources of infection, suggesting more extensive surveys are required to understand the transmission of this parasite.
疾病表现的多变性、能感染人类和其他动物的寄生虫的多个谱系。长期以来，人们一直怀疑某些亚型的芽囊原虫可能具有更高或更低的致病性，局限于特定的宿主，或其地理分布存在限制。在美国俄勒冈州，芽囊原虫是粪便标本中最常遇到的寄生虫，但亚类的多样性尚不清楚。在这项研究中，从出现与芽囊原虫病相关症状的个体中采集粪便样本，通过聚合酶链反应检测寄生虫的存在，并对 DNA 进行测序以进行亚型分型。19 名受检者中有 5 名寄生虫检测呈阳性，所有受检者的粪便卵和寄生虫检查也呈阳性。对小亚基核糖体 DNA 和延伸因子 1α 基因进行 DNA 测序，然后进行系统发育亚类分型，鉴定出 5 种独特的亚类，代表芽囊原虫亚型 1、2、3、4 和 8。感染的存在或不存在与任何特定症状均无关联，但所有受感染的个体均报告有腹痛和疲劳。多种亚型表明存在多种感染源，这表明需要进行更多的调查，以了解这种寄生虫的传播。
