Are IBS and Chronic Fatigue Caused by Giardiasis?

Giardia lamblia is a parasitic organism that is spread by fecal-oral contact, and causes acute diarrhea.  It can exist outside the body in a cyst form, and is a commonly found in the feces of domestic animals.  It commonly causes ‘traveler’s diarrhea’, and may be responsible for diarrhea outbreaks in daycare centers.

Not much is known about long-term effects of infection with G. lamblia, or giardiasis, as it’s called.  Norwegian researchers have studied the results of 3-year follow-up of cases of giardiasis, and published their results online in the journal Gut.

Mailed questionnaires were sent out that allowed the follow-up data on 817 patients infected by water-borne G. lamblia with that from 1,128 healthy controls matched for age and gender. Confirmation of infection was obtained by the presence of G. lamblia cysts in the feces of the patients.       

As many as 41% of the giardiasis group reported developing irritable bowel syndrome (IBS), compared with 14% of the control group.  And chronic fatigue was reported by 46% of the giardiasis group, compared with 12% in the controls.  IBS and chronic fatigue were associated, so that the risk for developing both IBS and chronic fatigue in the giardiasis group was 6.8 times that in the controls.

These numbers show the importance of considering G. lamblia as a cause of infectious gastroenteritis, so that such infections can be treated promptly.