Giardia infection may lead to persistent IBS, chronic fatigue

NEW YORK - Giardia infection may cause long-term abdominal symptoms and fatigue after the parasite has been eradicated, researchers from Norway report.

In 2004 in Bergen, Norway, a large number of people were infected and had giardiasis during a waterborne outbreak in the town. "Many of these people did not fully recover after successful treatment, and were referred to the hospital where I worked as a physician at the time," Dr. Kurt Hanevik from University of Bergen told Reuters Health by email.

"After a thorough medical work-up, we concluded that they had post-infectious irritable bowel syndrome (IBS)," he said. "However, the patients told us that their main problem was not the variable abdominal pain, diarrhea and bloating, (but rather) a lasting fatigability, limiting their daily activities to a minimum. Their symptoms fitted well with the enigmatic chronic fatigue syndrome, a condition many of them fulfilled the criteria for."

This led Dr. Hanevik and his colleagues to launch a population-based study to further investigate these long term complaints. The study included 748 of the 1,252 people with laboratory-confirmed Giardia infection during the 2004 outbreak and 878 matched controls.

Online August 12 in Clinical Infectious Diseases, they report that the prevalence of IBS by Rome III criteria (39.4%) and chronic fatigue (30.8%) were both significantly higher in the exposed group six years after laboratory confirmed giardiasis compared to controls, with adjusted relative risks of 3.4 and 2.9, respectively.

From three to six years after Giardia infection, recovery from chronic fatigue was more pronounced than recovery from IBS (15.3% vs 6.7%). In the Giardia group, both conditions were more persistent over time than in controls.

Dr. Hanevik told Reuters Health, "This parasite easily transmits in areas with poor sanitation and is therefore very common in developing countries. In developed countries it is seen in travelers returning from these areas and also it is a frequent cause of diarrhea outbreaks when drinking water becomes contaminated."

Based on the current observations, Giardia-induced IBS and/or chronic fatigue "could be considered a differential diagnosis, especially in returning travelers who present with such symptoms and where infectious microorganisms are not detected," the study team advises in their paper.

"I think awareness that fatigue and long-term abdominal complaints can follow Giardia infection is the main lesson here," Dr. Hanevik told Reuters Health. "This knowledge can be used to advise patients about the prognosis of their symptoms; that they may slowly but gradually improve. Especially we saw in our own clinical practice that young adults could fully recover from the chronic fatigue over a few years, and this was supported by the study results."


Clin Infect Dis 2014.

References: Reuters Health
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