Blastocystis hominis is a microscopic organism that may be found in the stools of healthy people who aren't having any digestive symptoms. Blastocystis hominis is also sometimes found in the stools of people who have diarrhea, abdominal pain or other gastrointestinal problems.
Researchers don't yet fully understand the role that Blastocystis hominis plays, if any, in causing an infection. Certain forms of Blastocystis hominis may be more likely to be linked to an infection with symptoms. Sometimes, blastocystis simply lives in a person's digestive tract without causing harm.
A Blastocystis hominis infection usually clears up on its own. There are no proven treatments for these infections. But, if your symptoms don't get better, your doctor may recommend trying certain medications.