Blastocystis hominis is a microscopic parasite sometimes found in the stools of healthy people as well as in the stools of those who have diarrhea, abdominal pain or other gastrointestinal problems. Infection with blastocystis is called blastocystosis.
Researchers don’t yet fully understand the role that blastocystis plays, if any, in causing an infection. Certain subtypes of blastocystis may be more likely to cause symptomatic infection, or may pose a risk only when combined with other types of infection. In some cases, blastocystis simply resides in the digestive tract without causing harm.
How do you get Blastocystosis and how is it spread?
The Blastocystis ‘hominis’ parasite lives in the intestine of infected humans or animals (e.g., cats, dogs, pigs, horses, cattle). Millions of germs can be released in a bowel movement of an infected human or animal. Blastocystis ‘hominis’ is found on surfaces or in soil, food, or water that has been contaminated with the feces from infected humans or animals. You can become infected after accidentally swallowing the parasite; you cannot become infected through contact with blood. Blastocystis ‘hominis’ can be spread by:
- Accidentally swallowing Blastocystis ‘hominis’ picked up from surfaces (such as bathroom fixtures, changing tables, diaper pails, or toys) contaminated with feces from an infected person or animal.
- Drinking water or using ice made from contaminated sources (e.g., lakes, streams, shallow [less than 50 feet] or poorly monitored or maintained wells).
- Swallowing recreational water contaminated with Blastocystis ‘hominis’. Recreational water includes water in swimming pools, water parks, hot tubs or spas, fountains, lakes, rivers, springs, ponds, or streams that can be contaminated with feces or sewage from humans or animals.
- Eating uncooked food contaminated with Blastocystis ‘hominis’.
- Having contact with someone who is ill with Blastocystosis.
- Traveling to countries where Blastocystosis is common and being exposed to the parasite as described in the bullets above.
What are the symptoms of Blastocystosis?
Blastocystis ‘hominis’ infection can cause a variety of intestinal signs or symptoms, which include
- Abdominal pain
- Gas or flatulence
- Greasy stools that tend to float
- Upset stomach or nausea
Patients also report fatigue, skin rashes, and joint pain. Some people with Blastocystis ‘hominis’infection have severe symptoms, while others have no symptoms at all. In this class of disease, researchers have found that people with more severe symptoms may be infected with more virulent types of microbes, and also may have a genetic makeup which causes the microbe to produce more severe illness.