title: Irritable bowel syndrome and chronic fatigue 6 years after giardia infection: a controlled prospective cohort study.
abstract: BACKGROUND
  Functional gastrointestinal disorders and fatigue may follow acute infections. This study aimed to estimate the persistence, prevalence, and risk of irritable bowel syndrome and chronic fatigue 6 years after Giardia infection.
  
  
  METHODS
  We performed a controlled prospective study of a cohort of 1252 individuals who had laboratory-confirmed Giardia infection during a waterborne outbreak in 2004. In total, 748 cohort cases (exposed) and 878 matched controls responded to a postal questionnaire 6 years later (in 2010). Responses were compared to data from the same cohort 3 years before (in 2007).
  
  
  RESULTS
  The prevalences of irritable bowel syndrome (39.4%) by Rome III criteria and chronic fatigue (30.8%) in the exposed group 6 years after giardiasis were significantly elevated compared with controls, with adjusted relative risks (RRs) of 3.4 (95% confidence interval [CI], 2.9-3.9) and 2.9 (95% CI, 2.3-3.4), respectively. In the exposed group, the prevalence of irritable bowel syndrome decreased by 6.7% (RR, 0.85 [95% CI, .77-.93]), whereas the prevalence of chronic fatigue decreased by 15.3% from 3 to 6 years after Giardia infection (RR, 0.69 [95% CI, .62-.77]). Giardia exposure was a significant risk factor for persistence of both conditions, and increasing age was a risk factor for persisting chronic fatigue.
  
  
  CONCLUSIONS
  Giardia infection in a nonendemic setting is associated with an increased risk for irritable bowel syndrome and chronic fatigue 6 years later. The prevalences of both conditions decrease over time, indicating that this intestinal protozoan parasite may elicit very long-term, but slowly self-limiting, complications.
authors.affiliation: Department of Clinical Science, University of Bergen.
authors.forename: Kurt
authors.initials: K
authors.lastname: Hanevik
authors.affiliation: Research Unit for General Practice, Uni Research Health.
authors.forename: Knut-Arne
authors.initials: KA
authors.lastname: Wensaas
authors.affiliation: Research Unit for General Practice, Uni Research Health Department of Global Public Health and Primary Care, University of Bergen.
authors.forename: Guri
authors.initials: G
authors.lastname: Rortveit
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen Centre for Clinical Research.
authors.forename: Geir Egil
authors.initials: GE
authors.lastname: Eide
authors.affiliation: National Centre for Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway.
authors.forename: Kristine
authors.initials: K
authors.lastname: Mørch
authors.affiliation: Department of Clinical Science, University of Bergen.
authors.forename: Nina
authors.initials: N
authors.lastname: Langeland
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002648:Child; D015673:Fatigue Syndrome, Chronic / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D005873:Giardiasis / Q000150:complications*; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000453:epidemiology* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D016017:Odds Ratio; D015995:Prevalence; D011446:Prospective Studies; D012306:Risk; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Giardia; chronic fatigue; irritable bowel syndrome; postinfectious