Tuesday, December 30, 2014

This Month In Blastocystis Research - Welcome 2015! Edition

2014 is coming to an end, and I'm looking very much forward to 2015, which will be the year of the 1st International Blastocystis Symposium. We are busy making all the preparations, and we hope that many of our colleagues will put priority to the event. For more details, please look up www.blastomeeting2015.com

Just before Christmas, I handed in a funding proposal that will hopefully turn out to be successful; if it is, it will enable me to fund three post docs/experienced scientists who will be working on Blastocystis genomics, animal experimental model work, and Blastocystis in the gut microbiota context, all three projects serving to identify the role of the parasite in health and disease. I've never been crossing my fingers as much as I am now... I will only know in 6 months from now whether I've been successful or not, so it's a long wait!

Two new papers have come to my attention. One deals with identification of a new host for Blastocystis - the brown bear (Ursus arctos); the other one is about the finding of Blastocystis in a case of appendicular peritonitis.

Ursus arctos - new host for Blastocystis (Source).

So far, Blastocystis has been identified in many larger mammals. Mostly synanthropic animals and animals in captivity have been sampled. Meanwhile, we know little about Blastocystis in 'the wild', in sylvatic animals. A team from Slovakia took to collecting 16 stool samples from brown bears in the Poloniny National Park; eight of them were positive for Blastocystis ST3, a subtype found mainly in primates, but also occasionally in a variety of other hosts. Interestingly, the team reported that the ST3 sequence amplified from the samples were identical to a sequence that we have deposited in GenBank (HQ909889) isolated from a human. We have studied ST3 from human and non-human primates, who are both common hosts of ST3. However, we have also come to realise that ST3 strains in humans differ genetically from ST3 of non-human primates, i.e., it appears not to be the same strains circulating in human and non-human primates. I wouldn't have been surprised to find a bear-specific allele of ST3, but apparently, the bears in the study harboured ST3 identical to ST3 in humans.

Blastocystis is a frequent finding in large mammals such as cows, pigs, camels, and, possibly, bears. One of my colleagues recently asked me: How about horses? A parasitologist herself with a vast experience in both human and animal parasitology, she told me that she did not remember coming across Blastocystis in horse manure. And we wondered why... Assuming that exposure does not differ between horses and other larger, synanthropic mammals, the reason why horses might not harbour Blastocystis may be due to factors such as diet, digestion, microbiota, and maybe competing eukaryotic intestinal fauna. However, I believe that horses have been infrequently sampled, and so we need more data to be able to 'ruminate' further on this.

Since parasites such as Dientamoeba and Blastocystis are lodged in the colon, including the coecum, their potential role in e.g. appendicitis and related conditions could warrant scrutiny. Fréalle and colleagues reported a case of appendicitis with suppuration into the recto-uterine pouch and reflex ileus in a 9-year-old girl returning to France after a 1-month stay in Casablanca, Morocco, admitted to Lille University Hospital, France. The authors were unable to detect enteropathogenic bacteria such as Salmonella, Shigella, Campylobacter, Yersinia enterocolitica, adenovirus, and rotavirus, but "multimicrobial flora" was detected in the peritoneal liquid and recto-uterine pouch. It would seem plausible to me that Blastocystis ended up in the peritoneum by chance along with other enteric micro-organisms, although the etiology of the inflammation remains uncertain. Appendicitis usually develops following obstruction of the lumen of the appendix, either due to hyperplasia of lymphoid tissue or faeces becoming incarcerated in the mucosal tissue; however, other causes are have also been observed, e.g. pinworm infection.

It would like to finish off by a ***Happy New Year***, at the same time celebrating page view #300,000!


Fréalle, E., El Safadi, D., Cian, A., Aubry, E., Certad, G., Osman, M., Wacrenier, A., Dutoit, E., Creusy, C., Dubos, F., & Viscogliosi, E. (2015). Acute Blastocystis-Associated Appendicular Peritonitis in a Child, Casablanca, Morocco Emerging Infectious Diseases, 21 (1), 91—94 DOI: 10.3201/eid2101.140544

Valenčáková, A., Kandráčová, P., Kalinová, J., Danišová, O., Hasajová, A. (2014). Detection of Blastocystis hominis subtype 3 in the brown bear in the Slovak Republic. Folia Veterinaria, 58, 3: 175—178. http://www.uvlf.sk/sites/default/files/folia-veterinaria/fv_3_14_web.pdf#page=32