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Friday, November 22, 2013

Do IBS Patients Lack Blastocystis and Dientamoeba??

I feel like sharing data from a poster created by one of my colleagues, Dr Laura Rindom Krogsgaard who works at Køge Sygehus, Denmark. She presented the poster last month at the United European Gastrointestinal (UEG) Week in Berlin.

Laura is currently doing a very interesting survey on IBS and IBS-like symptoms in Danish individuals. Her first publication was on the epidemiology of IBS in Denmark (see literature list below). She performed a web-based survey, using YouGov Zapera, and questionnaires were emailed to a web panel (n = 19,567) representative of the general Danish population aged 18-50 years containing info on gender, age, geography and type of intestinal symptoms (if any). IBS and subtypes were estimated by the Rome III criteria. Of 6,112 responders, 979 (16%) fulfilled the Rome III criteria for IBS and had no organic diagnosis likely to explain their symptoms. IBS subtypes detected included  mixed IBS (36%), IBS with diarrhea (33%), IBS with constipation (18%), and unsubtyped IBS (11%).

At the Laboratory of Parasitology, we helped Laura analyse stool samples from survey participants for parasites. Not surprisingly, Blastocystis and Dientamoeba were by far the most common parasites detected; however, it appeared that individuals with IBS symptoms were less likely to be colonised by these parasites than their controls! Which means that we have a situation reminiscent of that seen in IBD patients, only less pronounced. 

Laura was able to survey symptom developement over 1 year and compare this to the incidence of Blastocystis and Dientamoeba, and none of the parasites (indvidually or in co-infection) were linked to symptom development.

Indeed, Laura's data are in line with the general tendency that we see for Blastocystis (see figure below). Blastocystis appears to be rare in individuals with perturbation of the intestinal microbiota (due to antibiotic treatment, inflammation, infection, diet, etc.), while common in healthy individuals, most of whom are probably characterised by high gut microbial diversity and thereby - apparently - the right substrate/growth conditions for Blastocystis.


Literature:

Krogsgaard LR, Engsbro AL, & Bytzer P (2013). The epidemiology of irritable bowel syndrome in Denmark. A population-based survey in adults ≤50 years of age. Scandinavian Journal of Gastroenterology, 48 (5), 523-9 PMID: 23506174

The entire poster "Dientamoeba fragilis and Blastocystis: Two parasites the irritable bowel might be missing" presented at the UEGweek can be viewed here via SlideShare.


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