During the outbreak in 2004 the parasite Giardia lamblia was detected in stool samples from 1,250 people. Of the 817 returning a health questionnaire three years later 355 (46%) was diagnosed with irritable bowel syndrome and 366 (46%) with chronic fatigue. This is more than three times as prevalent as among controls without prior giardiasis.
This association between giardiasis and long-term consequences was unknown before the Bergen outbreak, and the results represent a valuable contribution to the understanding both of giardiasis and of complications following infections.
About the project
Clinical consequences 3 years after the giardiasis outbreak
This project was the main part of Knut-Arne Wensaas’ PhD thesis from 2011: «Giardiasis in Bergen. Outbreak and clinical consequences». The project was launched after we had completed a smaller study from general practice and found that many patients had persisting gastrointestinal symptoms six and 12 months after the outbreak.
The main finding is a more than tripled risk of irritable bowel syndrome (IBS) and chronic fatigue compared to a control group without previous giardiasis.
We have also found that asthma and allergy is more prevalent in those with IBS and chronic fatigue in the control group, men not among the Giardia-patients. This suggests that Giardia-infection is a far more important factor for developing IBS or fatigue than the vulnerability represented by asthma and allergy. Other published data show that the Giardia-patients more often report excessive daytime sleepiness and food intolerance compared to the control group.
The project team
In addition to members from the Research Unit for General Practice the team is supplemented by professor Nina Langeland and post.doc. Kurt Hanevik (Department of Clinical Science, University of Bergen), dr. Kristine Mørk (Haukeland University Hospital) and professor Geir Egil Eide (Department of Global Public Health and Primary Care, University of Bergen).