It looks like people that picked up blasto from international travel more often have severe symptoms that people that got infected locally.

I am speculating this could have to do with sub-types. That people are more resistant to local sub-types possibly. But more research need to be done also here. So much we do not know about this parasite.

Another interesting study have found that

"Subtype Analysis of Blastocystis Isolates from Blastocystis Cyst Excreting Patients"

"However, in a recent study, only about 20% of Blastocystis-positive individuals were shown to excrete cysts. 17 It has been suggested that the cyst stage is the transmissible stage; however, it is not known whether, and in what ways, some or all of the other forms are transmissible."

http://www.ajtmh.org/content/80/4/588.full


Why would only 20% to 30% of Blasto-positive individuals excrete cyst form. One would think of different sub-types, but this paper found out this was not the case.

I am therefore speculating that blasto could have some type of cycle that we do not know about yet. Could it be that blasto has a longer cycle. Or could it simply be dependent on peoples diet? If not enough food (carbs??) for the blasto parasites they turn into cysts?

Could this explain why some people not get cured while other get cured by triple therapy. If only 20 to 30% also have cyst stage could it be that these respond less well to treatment, because cysts have in studies shown to be more resistant.

I am not sure if the medical community has tested and specific protocols for the subtypes ????