Skip to main content


Log in

Molecular characterization of Blastocystis species in Oregon identifies multiple subtypes

  • Original Paper
  • Published:
Parasitology Research Aims and scope Submit manuscript


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.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2

Similar content being viewed by others


  • Amin O (2006) Epidemiology of Blastocystis hominis in the United States. Res J Parasitol 1:1–10

    Article  Google Scholar 

  • Boorom KF, Smith H, Nimri L, Viscogliosi E, Spanakos G, Parkar U, Li LH, Zhou XN, Ok UZ, Leelayoova S, Jones MS (2008) Oh my aching gut: irritable bowel syndrome, Blastocystis, and asymptomatic infection. Parasit Vectors 1:40

    Article  PubMed  Google Scholar 

  • Clark CG (1997) Extensive genetic diversity in Blastocystis hominis. Mol Biochem Parasitol 87:79–83

    Article  CAS  PubMed  Google Scholar 

  • Guindon S, Gascuel O (2003) A simple, fast, and accurate algorithm to estimate large phylogenies by maximum likelihood. Syst Biol 52:696–704

    Article  PubMed  Google Scholar 

  • Hall TA (1999) BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucl Acids Symp Ser 41:95–98

    CAS  Google Scholar 

  • Ho LC, Armugam A, Jeyaseelan K, Yap EH, Singh M (2000) Blastocystis elongation factor-1α: genomic organization, taxonomy and phylogenetic relationships. Parasitology 121:135–144

    Article  CAS  PubMed  Google Scholar 

  • Ho LC, Jeyaseelan K, Singh M (2001) Use of the elongation factor-1 alpha gene in a polymerase chain reaction-based restriction-fragment-length polymorphism analysis of genetic heterogeneity among Blastocystis species. Mol Biochem Parasitol 112:287–291

    Article  CAS  PubMed  Google Scholar 

  • Hoevers J, Holman P, Logan K, Hommel M, Ashford R, Snowden K (2000) Restriction-fragment-length polymorphism analysis of small-subunit rRNA genes of Blastocystis hominis isolates from geographically diverse human hosts. Parasitol Res 86:57–61

    Article  CAS  PubMed  Google Scholar 

  • Jones MS II, Ganac RD, Hiser G, Hudson NR, Le A, Whipps CM (2008) Detection of Blastocystis from stool samples using real-time PCR. Parasitol Res 103:551–557

    Article  PubMed  Google Scholar 

  • Jones MS II, Whipps CM, Ganac RD, Hudson NR, Boroom K (2009) Association of Blastocystis subtype 3 and 1 with patients from an Oregon community presenting with chronic gastrointestinal illness. Parasitol Res 104:341–345

    Article  PubMed  Google Scholar 

  • Noël C, Peyronnet C, Gerbod D, Edgcomb VP, Delgado-Viscogliosi P, Sogin ML, Capron M, Viscogliosi E, Zenner L (2003) Phylogenetic analysis of Blastocystis isolates from different hosts based on the comparison of small-subunit rRNA gene sequences. Mol Biochem Parasitol 126:119–123

    Article  PubMed  Google Scholar 

  • Noël C, Dufernez F, Gerbod D, Edgcomb VP, Delgado-Viscogliosi P, Ho LC, Singh M, Wintjens R, Sogin ML, Capron M, Pierce R, Zenner L, Viscogliosi E (2005) Molecular phylogenies of Blastocystis isolates from different hosts: implications for genetic diversity, identification of species, and zoonosis. J Clin Microbiol 43:348–355

    Article  PubMed  Google Scholar 

  • Posada D, Crandall KA (1998) Modeltest: testing the model of DNA substitution. Bioinformatics 14:817–818

    Article  CAS  PubMed  Google Scholar 

  • Ronquist F, Huelsenbeck JP (2003) MrBayes 3: Bayesian phylogenetic inference under mixed models. Bioinformatics 19:1572–1574

    Article  CAS  PubMed  Google Scholar 

  • Scicluna SM, Tawari B, Clark CG (2006) DNA barcoding of Blastocystis. Protist 157:77–85

    Article  CAS  PubMed  Google Scholar 

  • Souppart L, Sanciu G, Cian A, Wawrzyniak I, Delbac F, Capron M, Dei-Cas E, Boorom K, Delhaes L, Viscogliosi E (2009) Molecular epidemiology of human Blastocystis isolates in France. Parasitol Res 105:413–421

    Article  PubMed  Google Scholar 

  • Stensvold CR, Suresh GK, Tan KS, Thompson RC, Traub RJ, Viscogliosi E, Yoshikawa H, Clark CG (2007) Terminology for Blastocystis subtypes—a consensus. Trends Parasitol 23:93–96

    Article  PubMed  Google Scholar 

  • Stensvold CR, Alfellani MA, Nørskov-Lauritsen S, Prip K, Victory EL, Maddox C, Nielsen HV, Clark CG (2009a) Subtype distribution of Blastocystis isolates from synanthropic and zoo animals and identification of a new subtype. Int J Parasitol 39:473–479

    Article  CAS  PubMed  Google Scholar 

  • Stensvold CR, Lewis HC, Hammerum AM, Porsbo LJ, Nielsen SS, Olsen KE, Arendrup MC, Nielsen HV, Mølbak K (2009b) Blastocystis: unravelling potential risk factors and clinical significance of a common but neglected parasite. Epidemiol Infect 27:1–9

    Google Scholar 

  • Swofford DL (1998) PAUP*: phylogenetic analysis using parsimony (*and other methods). Version 4. Sinauer Associates, Sunderland

    Google Scholar 

  • Tan KSW (2004) Blastocystis in humans and animals: new insight using modern methodologies. Vet Parasitol 126:121–144

    Article  PubMed  Google Scholar 

  • Thompson JD, Gibson TJ, Plewniak F, Jeanmougin F, Higgins DG (1997) The ClustalX windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Res 24:4876–4882

    Article  Google Scholar 

  • Yoshikawa H, Abe N, Iwasawa M, Kitano S, Nagano I, Wu Z, Takahashi Y (2000) Genomic analysis of Blastocystis hominis strains isolated from two long-term health care facilities. J Clin Microbiol 38:1324–1330

    CAS  PubMed  Google Scholar 

Download references


Funding for this project was provided by a Blastocystis Foundation grant to MLK and LEB. CMW thanks the Nevada Genomics Center for DNA sequencing services which are supported in part by a grant from the Nevada IDeA Network of Biomedical Research Excellence (2 P20 RR016463).

Author information

Authors and Affiliations


Corresponding author

Correspondence to Christopher M. Whipps.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Whipps, C.M., Boorom, K., Bermudez, L.E. et al. Molecular characterization of Blastocystis species in Oregon identifies multiple subtypes. Parasitol Res 106, 827–832 (2010).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: