Irritable Bowel Syndrome and GI Parasites

With all this talk about the gut microbiome, we haven’t discussed gastrointestinal parasites and how they may play a role in gut dysbiosis.

Parasites are one thing that don’t typically come to mind when thinking about unpleasant GI symptoms like diarrhea and abdominal pain… but should they be given more credit for causing IBS-like symptoms? 

In developed nations like the US, parasites are given little attention when it comes to symptoms of GI distress because of factors like water purification and filtration, cleanliness and sanitation. A majority of parasitic infections are noted in developing nations due to the lack of these resources.

Certain risk factors for contracting parasites:

-          International travel where certain parasites are common

-          Poor sanitation (water and food)

-          Poor hygiene

-          Age: children and elderly are more likely to become infected

-          Weakened immune system

There is research suggesting the possible role of these 3 parasites in the formation and exacerbation of IBS symptoms:

Blastocystis hominis – commonly found in human feces. May cause IBS through increased inflammation and causing intestinal permeability. This parasite was found in higher amounts in patients who were diagnosed with IBS.

Dientamoeba fragilis – commonly found in human feces. Some studies have identified that this parasite multiplies in the presence of certain bacterial flora which can lead to dysbiosis. It possibly causes chronic illness that mimics IBS symptoms through cell damage and cell death of the epithelial cells of the intestines.

Giardia lamblia – found in soil and water that has been contaminated with feces from infected people or animals. It can spread easily from person to person through water, food, surfaces or objects. However, the most common way to get it is by swallowing contaminated drinking water or water from lakes, rivers, and pools

Giardia infection can be chronic and cause IBS-like symptoms through increasing inflammation, altering the gut microbiota, weakening the bodies inflammatory responses, altering neurotransmitter signaling and decrease enterochromaffin cells (which play a role in maintaining gastrointestinal motility and secretion).

More research is needed to confirm these possible mechanisms in relation to IBS but it is plausible to speculate these organisms may play a role in gut dysbiosis. 

If you have chronic diarrhea and IBS symptoms it might be plausible to seek out help to rule out if it is due to a parasitic infection. This is especially true if you have visited areas that are known to have parasites or have poor sanitation. Your doctor can take a stool sample to test for parasites. In some instances, blood work or an endoscopy may be helpful in diagnosing a parasitic infection.

Common treatments for parasitic infections include:

-          Medications

-          Nutrition intervention

o   Limiting simple carbohydrates (sugar), consuming more fiber, taking probiotics

-          Herbal remedies

-          Homeopathy  

As always, talk with your healthcare provider about your symptoms and if you suspect you have a parasite. They will be able to walk you through treatment options and monitor your progress. 
  1. Riaz M, Aslam N, Zainab R, et al. Prevalence, risk factors, challenges, and the currently available diagnostic tools for the determination of helminths infections in human. European Journal of Inflammation. January 2020.
  2. Shariati, A., Fallah, F., Pormohammad, A., Taghipour, A., Safari, H., Chirani, A. S., Sabour, S., Alizadeh-Sani, M., & Azimi, T. (2019). The possible role of bacteria, viruses, and parasites in initiation and exacerbation of irritable bowel syndrome. Journal of cellular physiology, 234(6), 8550–8569. 
  3. United States, Department of Health and Human Services, Centers for Disease Control and Prevention. “Parasites- Giardia.” Centers for Disease Control and Prevention, 26 February 2021, 

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