Once thought to be a harmless yeast, Blastocystis hominis a microscopic single-celled protozoal parasite. It behaves like a tiny animal — hunting and gathering other microbes for food—one reason why having a balanced gut flora is important. Healthy gut floras do not support large amounts of parasites. Many protozoa inhabit your gastrointestinal tract and are harmless; others cause disease.
One wonders why we don’t pick up Toxoplasma more often—especially for those of us who own cats. Could it be that we build up immunity to this organism if our immune system is functioning? It would seem to make sense as serologic surveys show that 7-94% of various populations are infected with the organism and are usually symptomatic. The disease occurs worldwide. If an infection is found, there are antibiotics which can be taken, so early diagnosis is especially urgent for those pregnant or immunocompromised. Children as well are at risk.