People with Giardia infections appear to have an increased risk for irritable bowel syndrome and chronic fatigue lasting as long as 6 years after the infection, according to data published in Clinical Infectious Diseases.
According to Kurt Hanevik, MD, of the University of Bergen in Norway, the investigators initiated this study after patients who had been infected with giardiasis related to a waterborne outbreak in 2004 were found to have post-infection irritable bowel syndrome (IBS) and severe fatigue.
“Physicians should be aware that Giardia infection may cause long-term abdominal symptoms and fatigue even after the parasite has been eradicated,” Hanevik told Infectious Disease News. “This knowledge can be used to advise patients about these complications and that they may gradually improve. We also saw in our clinical practice that young adults could fully recover from the chronic fatigue over a few years, and this was supported by the study results.”
The researchers conducted a controlled, prospective study that included 1,252 individuals with a confirmed Giardia infection related to a waterborne outbreak in Bergen, Norway, in 2004. The study also included 2,504 age and gender matched controls. The exposed individuals and the controls were asked to fill out questionnaires about fatigue and irritable bowel syndrome (IBS) 6 years after the outbreak.
The questionnaires were completed by 748 (60.4%) exposed individuals and 878 (35.9%) controls. The prevalence of chronic fatigue in the exposed individuals was 30.8% vs. 11% in the controls (RR=2.9; 95% CI, 2.3-3.4). In the exposed groups, 65% of the chronic fatigue cases were attributed to previous giardiasis. The prevalence of IBS was 39.4% in the exposed individuals vs. 11.6% in the controls (RR=3.4; 95% CI, 2.9-3.9). In the exposed group, 70.5% of the cases were attributable to previous giardiasis.
There was a significant decrease in both IBS and chronic fatigue in the exposed group from 3 years post-exposure to 6 years post-exposure, but there was no change among the controls. Giardia exposure was a risk factor for the persistence of both IBS and chronic fatigue. Increasing age was also associated with chronic fatigue.
“We will try to follow this cohort of Giardia-exposed patients and controls for some years,” Hanevik said. “We are also discussing the possibility of assessing a genetic predisposition to develop these complications by looking at genes regulating mucosal immune responses and gut barrier function.” — by Emily Shafer
Disclosure: The researchers report no relevant financial disclosures.