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Current Views on the Clinical Relevance of Blastocystis spp.


Blastocystis is an enteric protistan parasite of uncertain clinical relevance. Recent studies indicate that the parasite is a species complex and humans are potentially hosts to nine Blastocystis subtypes, most of which are zoonotic. Subtype 3 is the most common in prevalence studies, followed by subtype 1. Laboratory diagnosis is challenging; the currently recommended diagnostic approach is trichrome staining of direct smears coupled with stool culture. Polymerase chain reaction testing from stools or culture is useful for determining Blastocystis subtype information. The controversial pathogenesis of Blastocystis is attributed to subtype variations in virulence; although current studies seem to support this idea, evidence suggests other factors also contribute to the clinical outcome of the infection. Clinical signs and symptoms of blastocystosis include abdominal pain, diarrhea, bloating, and flatulence. Extraintestinal manifestations, predominantly cutaneous, also were reported. In vitro and animal studies shed new light on the pathobiology of Blastocystis.

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References and Recommended Reading

Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance

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Research from Dr. Tan’s laboratory is supported by generous grants from the Academic Research Fund, National Medical Research Council (NMRC), and Biomedical Research Council. Dr. Wu is a postdoctoral fellow funded by the NMRC. Haris Mirza and Joshua Teo are postgraduate students funded by National University of Singapore Research Scholarships.


No potential conflict of interest relevant to this article was reported.

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Correspondence to Kevin S. W. Tan.

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Tan, K.S.W., Mirza, H., Teo, J.D.W. et al. Current Views on the Clinical Relevance of Blastocystis spp.. Curr Infect Dis Rep 12, 28–35 (2010).

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  • Blastocystis
  • Pathogenesis
  • Subtypes
  • Diagnosis
  • Prevalence