This Month in Blastocystis Research (FEB 2015)

Before heading off to visit dear colleagues at the Public Health Agency of Sweden tomorrow morning, I thought I'd do a quick 'This Month...' post.

Tropical Parasitology has published a paper by Elghareeb and colleagues on  'Laboratory Diagnosis of Blastocystis in Diarrheic Patients'. I was asked to do a Guest Commentary on their paper, and if your're interested you can download my comments here for free (html version). The paper by Elghareeb et al. should also be free for download at the website.

I have been very lucky to work together with Dr Prashant K Pandey and his colleauges in Pune, India. Together we just published the first data on Blastocystis subtypes ever to appear in India for what I know. We subtyped Blastocystis in a cohort of healthy Indian individuals, and found ST1 and ST3 in 27/100 adult individuals tested, while other common subtypes, ST2 and ST4, were absent. Remarkably, ST3 was seen in all positive individuals, while ST1 was seen only in mixed infections. The strains (alleles) found in India were no different to those found in for instance Europe.

There is a paper out by Rossen and colleagues from The Netherlands showing that Blastocystis is relatively uncommon in patients with active ulcerative colitis (UC) and significantly less common in UC patients (13.3%) than in healthy individuals (32.5%). This is completely in line with data that we generated in Denmark a couple of years ago. In fact, at two separate occasions we have been able to look into patients with inflammatory bowel disease. In both cases (one study has been submitted for publication), hardly any Blastocystis was found in patients with Crohn's disease, while a few patients with UC were positive; however, mostly patients with inactive disease appeared to have Blastocystis, while those with flare-ups were negative. Therefore, the influence of dysbiosis on Blastocystis colonisation should be subject to further scrutiny.

A lot of action goes on at the official website for the 1st International Blastocystis Symposium in Ankara in May, with exactly three months to go! Why not take a minute to browse the programme for the Pre-Symposium Course and the Scientific Programme for the actual Symposium? Please go here to familiarise yourself with the new content. 
Also, conference abstracts are pouring in, - did you submit yours yet?

References

Elghareeb AS, Younis MS, El Fakahany AF, Nagaty IM, & Nagib MM (2015). Laboratory diagnosis of Blastocystis spp. in diarrheic patients. Tropical Parasitology, 5 (1), 36-41 PMID: 25709951

Stensvold, C. (2015). Laboratory diagnosis of Blastocystis spp Tropical Parasitology, 5 (1) DOI: 10.4103/2229-5070.149885  

Pandey PK, Verma P, Marathe N, Shetty S, Bavdekar A, Patole MS, Stensvold CR, & Shouche YS (2015). Prevalence and subtype analysis of Blastocystis in healthy Indian individuals. Infection, Genetics and Evolution: Journal of Molecular Epidemiology and Evolutionary Genetics in Infectious Diseases PMID: 25701123

Rossen NG, Bart A, Verhaar N, van Nood E, Kootte R, de Groot PF, D'Haens GR, Ponsioen CY, & van Gool T (2015). Low prevalence of Blastocystis sp. in active ulcerative colitis patients. European Journal of Clinical Microbiology & Infectious Diseases: Official Publication of the European Society of Clinical Microbiology PMID: 25680316

This Month in Blastocystis Research (SEP 2014)

Before leaving for Venice and Padova to introduce Blastocystis to the XXX National Congress of The Italian Society of Protistology (ONLUS), allow me to kick in just a few words for the September issue of 'This Month in Blastocystis Research'.

I will highlight two papers.

The first is a study from the US (Yes, - US data! How rare is that?). The team investigated the prevalence and subtype distribution of Blastocystis among client-owned and shelter-resident cats and dogs. Studies of Blastocystis in companion animals are actually quite rare. The authors used nested PCR for detection, followed by sequencing of PCR products. Interestingly, Blastocystis was not detected in any of the >100 fecal samples from client-owned animals. By comparison, Blastocystis was detected in 10/103 (9.7%) shelter-resident canines, and 12/103 (11.65%) shelter-resident felines. There was no significant difference in Blastocystis spp. carriage rates between the shelter-resident dogs and cats. It is likely that differences in diet and other types of exposure account for Blastocystis being found in shelter-resident animals and not in domestic animals. As for cats and dogs, we don't really know much about what to expect subtype-wise. These animals harboured ST10 mostly, a subtype that has only been found in artiodactyls, NHPs, and lemurs, so far, and - taking these new data into account - with little apparent host preference.

Viktor - an avid fox hunter (in 2007).

Other subtypes included ST1 and one case of ST3, and one case of what was most likely a new subtype - maybe! But then, few animals were positive, and given the different data on subtypes in cats and dogs, it's much too early to speculate on host specific subtypes... for now, it appears that there are none, and that maybe cats and dogs are not really natural hosts? A study by Wang and colleagues identified a plethora of subtypes in dogs: Among 22 positive dogs, most of which were from India, ST1, ST2, ST4, ST5, and ST6 were found. Again, nested PCR was used, and I might have a slight concern that this type of PCR approach is so sensitive that it will pick up the smallest quantity of Blastocystis, maybe even dead Blastocystis or other stages of Blastocystis not necessarily colonising the host (contamination, etc.). But I don't know. The authors of the US study noted that Blastocystis was unlikely to be associated with disease of the animals and were unable to establish a reservoir for human colonisation/infection in these animals.

I never got around to checking Viktor (our cat, pictured above) for Blastocystis. Now it's too late.

I would like to move on to another study. This time the data is from a paper that has just appeared in press in Clinical Gastroenterology and Hepatology. We  analysed faecal DNAs from patients diagnosed with irritable bowel syndrome and healthy individuals. The reason for doing this was due to the fact that intestinal parasite have been speculated to play a role in the development of IBS, a disease affecting about 16% of the adult Danish population. And so we thought that the prevalence of common parasites such as Blastocystis and Dientamoeba fragilis might be higher in IBS patients than in healthy individuals. The study was led by Dr Laura R Krogsgaard, who took a quite unusual approach to collecting questionnaires and faecal samples, namely by collaborating with the company YouGov Zapera.  
We obtained faecal samples from 483 individuals, of whom 186 were cases – ie. patients with IBS – and 297 were healthy controls. DNA was extracted directly from the stool using the easyMag protocol, and the faecal DNAs were submitted to real-time PCR based screening for Blastocystis, Dientamoeba, Entamoeba histolytica and E. dispar, Cryptosporidium, and Giardia.

Above you see the results of the various analyses. Blue columns represent healthy individuals, and orange columns represent IBS patients. Fifty percent of the healthy controls were positive for one or more parasites, while this proportion was significantly lower in IBS patients, 36%. Also for each individual parasite, the number of positive cases was higher among controls than among patients with IBS. Dientamoeba was the most common parasite among healthy controls and IBS patients. In terms of Blastocystis subtypes, the distribution of subtypes between the two groups was non-significant (data not shown).We ended up by concluding that our findings indicated that these parasites are not likely to play a direct role in the pathogenesis of IBS. Longitudinal studies are required to understand their role in gastrointestinal health. 

Still, the role of Blastocystis in human health and disease remains ambiguous, although lots of interesting data is emerging. In order to try and understand the theories behind Blastocystis' potential able to generate disease, I would like to point the readers' attention to a new review, developed by Ivan Wawrzyniak and his prolific colleauges.

Ciao!

References

Krogsgaard LR, Engsbro AL, Stensvold CR, Vedel Nielsen H, & Bytzer P (2014). The Prevalence of Intestinal Parasites is not Greater Among Individuals with IBS: a Population-Based Case-Control Study. Clinical Gastroenterology and Hepatology : the official clinical practice journal of the American Gastroenterological Association PMID: 25229421

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

Ruaux CG, & Stang BV (2014). Prevalence of Blastocystis in Shelter-Resident and Client-Owned Companion Animals in the US Pacific Northwest. PloS One, 9 (9) PMID: 25226285  

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 & Vectors, 6 PMID: 23883734

Wawrzyniak I, Poirier P, Viscogliosi E, Dionigia M, Texier C, Delbac F, & Alaoui HE (2013). Blastocystis, an unrecognized parasite: an overview of pathogenesis and diagnosis. Therapeutic Advances in Infectious Disease, 1 (5), 167-78 PMID: 25165551