A Penny For Your Thoughts

So, what should we do about Blastocystis? What do we want to know?

I believe the imminent answer to the latter question is easy: We want to know whether it’s pathogenic, whether we should treat it and how. But I also think that there are many other interesting aspects of Blastocystis which are also of broad interest to the general public, namely: How about the many cases of asymptomatic Blastocystis carriage? What does Blastocystis do in our guts? Could it have any potentially beneficial impact on our health?

Given the fact that Blastocystis has not been implicated in any outbreaks (admittedly: I guess that no one actually ever looked for Blastocystis in outbreak investigations... except for me!), I reckon that the chance of it being involved in acute diarrhoea is small. So, in that respect it's very different from the other intestinal protists such as Giardia, Cryptosporidium, Cyclospora, microsporidia, even Entamoeba histolytica. It's actually more reminiscent of helminth infections, which are are often chronic, and when light hardly give rise to symptoms (depending on species that is!).So I'm more thinking along the lines of co-evolution, adaptation, etc.

Maybe future research will call for a shift in paradigm, but until then I think that we should do what we already can, just at a larger scale and see where it takes us, namely:

Where Are We On Blastocystis Subtypes?

As mentioned, Blastocystis exhibits remarkable intrageneric diversity, which is continuously being explored by us and our colleagues. We are convinced that the genus of Blastocystis comprises multiple species, but for now we call them "ribosomal lineages" or "subtypes" and allocate numbers to each subtype, hence ST1, ST2, etc. While the number of subtypes that can be found in humans remains stable, we and our colleagues are still expanding the subtype universe in non-human hosts (I will be blogging on this shortly).

Barcoding currently represents state-of-the-art in Blastocystis subtyping, and luckily this method appears to gain a foothold in labs across the world.

Nine subtypes have been found in humans, but some of them only on rare occasions. A recent study going out from London School of Hygiene and Tropical Medicine and led by Dr Alfellani and published just now in Acta Tropica looked at 356 Blastocystis sequences from samples from the UK and Libya, but also from sub-Saharan Africa, namely Liberia and Nigeria.