Blastocystis Parasite Blog

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Blastocystis may be found in more than 1 billion people worldwide. We investigate the role of this parasite in health and disease. Blastocystis is a protist parasitising the intestine of humans and a variety of animals. We estimate that at least 1 billion people worldwide are colonised by this parasite, most of whom probably experience no more episodes of intestinal upset, e.g. diarrhoea, than the average individual. Blastocystis may colonise the intestine for a long time (i.e. months or years). Many species of Blastocystis are known, of which at least 9 have been found in humans. Such species are currently termed "subtypes" (STs). ST1, ST2, ST3 and ST4 are common in Europe. While ST1, ST2, and ST3 appear to have equal prevalences in patients with diarrhoea and healthy individuals, ST4 appears to be epidemiologically linked to diarrhoea and/or chronic conditions such as irritable bowel syndrome (IBS). There is no known efficient eradication strategy for Blastocystis. Although metronidazole is often prescribed for Blastocystis infections, there is conflicting reports on its efficacy. Even in combination with a luminal agent, such as paromomycin, Blastocystis eradication cannot be guaranteed. Read more here. I'm very interested in studies aiming to explore 1) Blastocystis in the environment 2) Why some people are colonised while others are not 3) Whether Blastocystis colonisation requires a certain intestinal flora (e.g. enterotype) to establish 4) To which extent human Blastocystis is acquired from animal reservoirs 5) Potential differences in virulence between subtypes or strains (by for instance comparative genomic studies) During my Blastocystis research, I and my colleagues have discovered/developed 1) New Blastocystis species 2) Precise molecular methods for accurate detection (PCR) 3) High resolution typing systems (MLST) for strain identification of Blastocystis 4) A standardised nomenclature for Blastocystis 5) A publicly available database for identification of subtypes and sequence data despository (please see links below) Using microscopy-, culture-based and molecular tools we have generated data that have shed light over the transmission and distribution of Blastocystis subtypes in human and animals.

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  • April 10, 2014
  • 01:16 AM
  • 55 views

Resources For Blastocystis Epidemiology Research

by Christen Rune Stensvold in Blastocystis Parasite Blog

An inventory of useful free online tools for studying the molecular epidemiology of Blastocystis.... Read more »

Alfellani MA, Taner-Mulla D, Jacob AS, Imeede CA, Yoshikawa H, Stensvold CR, & Clark CG. (2013) Genetic diversity of blastocystis in livestock and zoo animals. Protist, 164(4), 497-509. PMID: 23770574  

Alfellani MA, Stensvold CR, Vidal-Lapiedra A, Onuoha ES, Fagbenro-Beyioku AF, & Clark CG. (2013) Variable geographic distribution of Blastocystis subtypes and its potential implications. Acta tropica, 126(1), 11-8. PMID: 23290980  

Clark CG, van der Giezen M, Alfellani MA, & Stensvold CR. (2013) Recent developments in Blastocystis research. Advances in parasitology, 1-32. PMID: 23548084  

Stensvold CR, Suresh GK, Tan KS, Thompson RC, Traub RJ, Viscogliosi E, Yoshikawa H, & Clark CG. (2007) Terminology for Blastocystis subtypes--a consensus. Trends in parasitology, 23(3), 93-6. PMID: 17241816  

  • April 1, 2014
  • 09:05 PM
  • 64 views

This Month In Blastocystis Research (MAR 2014)

by Christen Rune Stensvold in Blastocystis Parasite Blog

Is Blastocystis a consistent finding in Senegalese children? Novel data seem to suggest so.... Read more »

  • March 16, 2014
  • 03:44 AM
  • 126 views

What's In A Name?

by Christen Rune Stensvold in Blastocystis Parasite Blog

Blastocystis is a parasite. But what makes a parasite, and are all parasites 'bad'?... Read more »

  • February 28, 2014
  • 02:39 PM
  • 273 views

This Month In Blastocystis Research (FEB 2014) - The Protease Edition

by Christen Rune Stensvold in Blastocystis Parasite Blog

The February issue of This Month In Blastocystis Research is mostly about Blastocystis proteases and their potential clinical significance. ... Read more »

Fayer R, Elsasser T, Gould R, Solano G, Urban J Jr, & Santin M. (2014) Blastocystis tropism in the pig intestine. Parasitology research. PMID: 24535732  

Denoeud F, Roussel M, Noel B, Wawrzyniak I, Da Silva C, Diogon M, Viscogliosi E, Brochier-Armanet C, Couloux A, Poulain J.... (2011) Genome sequence of the stramenopile Blastocystis, a human anaerobic parasite. Genome biology, 12(3). PMID: 21439036  

Olivo-Diaz A, Romero-Valdovinos M, Gudiño-Ramirez A, Reyes-Gordillo J, Jimenez-Gonzalez DE, Ramirez-Miranda ME, Martinez-Flores WA, Martinez-Hernandez F, Flisser A, & Maravilla P. (2012) Findings related to IL-8 and IL-10 gene polymorphisms in a Mexican patient population with irritable bowel syndrome infected with Blastocystis. Parasitology research, 111(1), 487-91. PMID: 22287022  

Puthia MK, Vaithilingam A, Lu J, & Tan KS. (2005) Degradation of human secretory immunoglobulin A by Blastocystis. Parasitology research, 97(5), 386-9. PMID: 16151742  

Wawrzyniak I, Texier C, Poirier P, Viscogliosi E, Tan KS, Delbac F, & El Alaoui H. (2012) Characterization of two cysteine proteases secreted by Blastocystis ST7, a human intestinal parasite. Parasitology international, 61(3), 437-42. PMID: 22402106  

Sio SW, Puthia MK, Lee AS, Lu J, & Tan KS. (2006) Protease activity of Blastocystis hominis. Parasitology research, 99(2), 126-30. PMID: 16518611  

  • February 3, 2014
  • 01:55 PM
  • 185 views

This Month In Blastocystis Research (JAN 2014)

by Christen Rune Stensvold in Blastocystis Parasite Blog

This Month In Blastocystis Research is introducing the possible benefits of polyparasitism (!) and pulls out an example of a potentially protecting effect of Blastocystis.... Read more »

Franke MF, Del Castillo H, Pereda Y, Lecca L, Fuertes J, Cárdenas L, Becerra MC, Bayona J, & Murray M. (2013) Parasite Infection and Tuberculosis Disease among Children: A Case-Control Study. The American journal of tropical medicine and hygiene. PMID: 24379242  

Archambaud C, Sismeiro O, Toedling J, Soubigou G, Bécavin C, Lechat P, Lebreton A, Ciaudo C, & Cossart P. (2013) The intestinal microbiota interferes with the microRNA response upon oral Listeria infection. mBio, 4(6). PMID: 24327339  

  • December 11, 2013
  • 02:11 AM
  • 270 views

Molecular Epidemiology: Developing a Language

by Christen Rune Stensvold in Blastocystis Parasite Blog

Standardised methods and broadly accepeted reference data are the bread and butter of molecular epidemiological studies of infectious organisms. This post highlights some of the issues related to molecular epidemiology terminology and draws parallels between research in Blastocystis and Cryptosporidium.... Read more »

Alfellani MA, Taner-Mulla D, Jacob AS, Imeede CA, Yoshikawa H, Stensvold CR, & Clark CG. (2013) Genetic diversity of blastocystis in livestock and zoo animals. Protist, 164(4), 497-509. PMID: 23770574  

Stensvold CR, Suresh GK, Tan KS, Thompson RC, Traub RJ, Viscogliosi E, Yoshikawa H, & Clark CG. (2007) Terminology for Blastocystis subtypes--a consensus. Trends in parasitology, 23(3), 93-6. PMID: 17241816  

Xiao L, Ryan UM, Fayer R, Bowman DD, & Zhang L. (2012) Cryptosporidium tyzzeri and Cryptosporidium pestis: which name is valid?. Experimental parasitology, 130(3), 308-9. PMID: 22230707  

  • December 4, 2013
  • 06:42 PM
  • 259 views

This Month in Blastocystis Research (NOV 2013)

by Christen Rune Stensvold in Blastocystis Parasite Blog

This Month in Blastocystis Research (NOV 2013)is mainly about new diagnostics and various treatment options.... Read more »

Roberts T, Ellis J, Harkness J, Marriott D, & Stark D. (2013) Treatment failure in patients with chronic Blastocystis infection. Journal of medical microbiology. PMID: 24243286  

  • November 22, 2013
  • 05:30 PM
  • 263 views

Do IBS Patients Lack Blastocystis and Dientamoeba??

by Christen Rune Stensvold in Blastocystis Parasite Blog

Healthy individuals appear to be more frequent carriers of the two parasites Blastocystis and Dientamoeba fragilis. We would like to know why and what the public health implications are of this.... Read more »

  • November 5, 2013
  • 10:56 AM
  • 244 views

A Shift of Paradigm in Blastocystis Research? Free paper in Trends in Parasitology!

by Christen Rune Stensvold in Blastocystis Parasite Blog

Opinion paper on Blastocystis in 'Trends in Parasitology' free for download all of November 2013.... Read more »

  • November 3, 2013
  • 04:13 AM
  • 282 views

This Month in Blastocystis Research (OCT 2013)

by Christen Rune Stensvold in Blastocystis Parasite Blog

A post about a selection of papers related to Blastocystis research emerging in October 2013.... Read more »

Maas L, Dorigo-Zetsma JW, de Groot CJ, Bouter S, Plötz FB, & van Ewijk BE. (2013) Detection of intestinal protozoa in paediatric patients with gastrointestinal symptoms by multiplex real-time PCR. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. PMID: 24131443  

  • October 16, 2013
  • 08:30 PM
  • 268 views

Dying to know about Dientamoeba?

by Christen Rune Stensvold in Blastocystis Parasite Blog

Similar to Blastocystis, Dientamoeba fragilis is a very common parasite in countries where other intestinal parasites are of low endemic occurrence. We are exploring the clinical significance of these parasites.... Read more »

Engsbro AL, Stensvold CR, Nielsen HV, & Bytzer P. (2012) Treatment of Dientamoeba fragilis in patients with irritable bowel syndrome. The American journal of tropical medicine and hygiene, 87(6), 1046-52. PMID: 23091195  

Ogren J, Dienus O, Löfgren S, Iveroth P, & Matussek A. (2013) Dientamoeba fragilis DNA detection in Enterobius vermicularis eggs. Pathogens and disease. PMID: 23893951  

Stark DJ, Beebe N, Marriott D, Ellis JT, & Harkness J. (2006) Dientamoebiasis: clinical importance and recent advances. Trends in parasitology, 22(2), 92-6. PMID: 16380293  

Stark D, Barratt J, Roberts T, Marriott D, Harkness J, & Ellis J. (2010) A review of the clinical presentation of dientamoebiasis. The American journal of tropical medicine and hygiene, 82(4), 614-9. PMID: 20348509  

Stensvold CR, Clark CG, & Röser D. (2013) Limited intra-genetic diversity in Dientamoeba fragilis housekeeping genes. Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases, 284-6. PMID: 23681023  

Stensvold CR, Lewis HC, Hammerum AM, Porsbo LJ, Nielsen SS, Olsen KE, Arendrup MC, Nielsen HV, & Mølbak K. (2009) Blastocystis: unravelling potential risk factors and clinical significance of a common but neglected parasite. Epidemiology and infection, 137(11), 1655-63. PMID: 19393117  

  • September 4, 2013
  • 05:01 PM
  • 288 views

Yes, we do take orders!

by Christen Rune Stensvold in Blastocystis Parasite Blog

The Laboratory of Parasitology, Statens Serum Institut, is now seeking to make diagnostic services available for customers outside Denmark. Doctors - and to some extent private persons - can order analyses directly, and it will also be possible for researchers to outsource diagnostic work to our laboratory.... Read more »

  • August 30, 2013
  • 10:27 PM
  • 356 views

This Month In Blastocystis Research (AUG)

by Christen Rune Stensvold in Blastocystis Parasite Blog

Quite a few papers relevant to Blastocystis research have made it to PubMed over the past month! Therefore, the August version of 'This Month in Blastocystis Research' is more like a list of papers short descriptions/comments, rather than one or two actual paper reviews.... Read more »

Li J, Deng T, Li X, Cao G, Li X, & Yan Y. (2013) A rat model to study Blastocytis subtype 1 infections. Parasitology research. PMID: 23892480  

Parija SC. (2013) Blastocystis: Status of its pathogenicity. Tropical parasitology, 3(1), 1. PMID: 23961433  

Sekar U, & Shanthi M. (2013) Blastocystis: Consensus of treatment and controversies. Tropical parasitology, 3(1), 35-9. PMID: 23961439  

Parija SC, & Jeremiah S. (2013) Blastocystis: Taxonomy, biology and virulence. Tropical parasitology, 3(1), 17-25. PMID: 23961437  

Ramírez JD, Sánchez LV, Bautista DC, Corredor AF, Flórez AC, & Stensvold CR. (2013) Blastocystis subtypes detected in humans and animals from Colombia. Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases. PMID: 23886615  

Wang W, Cuttell L, Bielefeldt-Ohmann H, Inpankaew T, Owen H, & Traub RJ. (2013) Diversity of Blastocystis subtypes in dogs in different geographical settings. Parasites , 215. PMID: 23883734  

  • July 29, 2013
  • 02:58 PM
  • 397 views

Birds of America

by Christen Rune Stensvold in Blastocystis Parasite Blog

This blog post highlights Blastocystis subtypes identified in birds on a global scale, in particular in passerine birds of America.... Read more »

Ramírez JD, Sánchez LV, Bautista DC, Corredor AF, Flórez AC, & Stensvold CR. (2013) Blastocystis subtypes detected in humans and animals from Colombia. Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases. PMID: 23886615  

Alfellani MA, Taner-Mulla D, Jacob AS, Imeede CA, Yoshikawa H, Stensvold CR, & Clark CG. (2013) Genetic diversity of blastocystis in livestock and zoo animals. Protist, 164(4), 497-509. PMID: 23770574  

Stensvold CR, Alfellani M, & Clark CG. (2012) Levels of genetic diversity vary dramatically between Blastocystis subtypes. Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases, 12(2), 263-73. PMID: 22116021  

Stensvold CR, Alfellani MA, Nørskov-Lauritsen S, Prip K, Victory EL, Maddox C, Nielsen HV, & Clark CG. (2009) Subtype distribution of Blastocystis isolates from synanthropic and zoo animals and identification of a new subtype. International journal for parasitology, 39(4), 473-9. PMID: 18755193  

  • July 22, 2013
  • 01:10 PM
  • 334 views

My 'Thoughts on Blastocystis' now as eBook in Amazon

by Christen Rune Stensvold in Blastocystis Parasite Blog

I started blogging about Blastocystis in March 2012, and I thought I’d publish some of the more elaborate posts in chronological order as a separate eBook with some minor re-editing, - sort of a ‘Blastocystis Research Diary’. The Blastocystis Parasite Blog has allowed me to vent new hypotheses and some alternative views on Blastocystis and its role in health and disease.... Read more »

Clark CG, van der Giezen M, Alfellani MA, & Stensvold CR. (2013) Recent developments in Blastocystis research. Advances in parasitology, 1-32. PMID: 23548084  

  • July 17, 2013
  • 06:30 PM
  • 399 views

ICOP XIV in Vancouver 28 July to 2 August 2013

by Christen Rune Stensvold in Blastocystis Parasite Blog

The 14th International Congress on Protistology takes place in Vancouver later this month. Here are some teasers, including some on Blastocystis.... Read more »

Denoeud F, Roussel M, Noel B, Wawrzyniak I, Da Silva C, Diogon M, Viscogliosi E, Brochier-Armanet C, Couloux A, Poulain J.... (2011) Genome sequence of the stramenopile Blastocystis, a human anaerobic parasite. Genome biology, 12(3). PMID: 21439036  

  • July 10, 2013
  • 08:30 PM
  • 407 views

This Month In Blastocystis Research (JUL)

by Christen Rune Stensvold in Blastocystis Parasite Blog

This Month In Blastocystis Research (JUL 2013) focuses on a symposium on Blastocystis that has been published in the open access journal Tropical Parasitology.... Read more »

  • June 21, 2013
  • 10:53 PM
  • 486 views

This Month In Blastocystis Research

by Christen Rune Stensvold in Blastocystis Parasite Blog

The universe of Blastocystis is continuously expanding. Here we report of three novel subtypes. We also suggest that livestock is not a major contributor to human Blastocystis infection.... Read more »

Alfellani MA, Taner-Mulla D, Jacob AS, Imeede CA, Yoshikawa H, Stensvold CR, & Clark CG. (2013) Genetic Diversity of Blastocystis in Livestock and Zoo Animals. Protist, 164(4), 497-509. PMID: 23770574  

Alfellani MA, Stensvold CR, Vidal-Lapiedra A, Onuoha ES, Fagbenro-Beyioku AF, & Clark CG. (2013) Variable geographic distribution of Blastocystis subtypes and its potential implications. Acta tropica, 126(1), 11-8. PMID: 23290980  

Alfellani MA, Jacob AS, Perea NO, Krecek RC, Taner-Mulla D, Verweij JJ, Levecke B, Tannich E, Clark CG, & Stensvold CR. (2013) Diversity and distribution of Blastocystis sp. subtypes in non-human primates. Parasitology, 140(8), 966-71. PMID: 23561720  

  • June 15, 2013
  • 05:09 AM
  • 497 views

Blastocystis - 'Monsters Inside Me'

by Christen Rune Stensvold in Blastocystis Parasite Blog

A blog post on when a documentary turns into fiction - or vice versa!... Read more »

Stensvold CR, Smith HV, Nagel R, Olsen KE, & Traub RJ. (2010) Eradication of Blastocystis carriage with antimicrobials: reality or delusion?. Journal of clinical gastroenterology, 44(2), 85-90. PMID: 19834337  

  • May 25, 2013
  • 09:49 AM
  • 441 views

This Month in Blastocystis Research

by Christen Rune Stensvold in Blastocystis Parasite Blog

This Month in Blastocystis Research is a bit meagre, but here's a chance to listen to a 1h related Blastocystis case story podcast...
... Read more »

Sakalar C, Uyar Y, Yürürdurmaz MA, Tokar S, Yeşilkaya H, Gürbüz E, Kuk S, & Yazar S. (2013) [Cloning of Blastocystis sp Subtype 3 Small-subunit Ribosomal DNA]. Turkiye parazitolojii dergisi / Turkiye Parazitoloji Dernegi , 37(1), 13-8. PMID: 23619039  

Ozyurt M, Kurt O, Mølbak K, Nielsen HV, Haznedaroglu T, & Stensvold CR. (2008) Molecular epidemiology of Blastocystis infections in Turkey. Parasitology international, 57(3), 300-6. PMID: 18337161  

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