Prevalence of fibromyalgia 10 years after infection with Giardia lamblia: a controlled prospective cohort study.

OBJECTIVES: To investigate whether acute infection with Giardia lamblia is associated with fibromyalgia 10 years after infection and whether fibromyalgia is associated with irritable bowel syndrome (IBS) and chronic fatigue (CF) in this setting. METHODS: A cohort study was established after an outbreak of G. lamblia in Bergen, Norway, 2004. Laboratory-confirmed cases and a matched control group were followed for 10 years. The main outcome was fibromyalgia 10 years after giardiasis, defined by the 2016 revisions of the fibromyalgia diagnostic criteria using the Fibromyalgia Survey Questionnaire (FSQ). RESULTS: The prevalence of fibromyalgia was 8.6% (49/572) among Giardia exposed compared to 3.1% (21/673) in controls (p<0.001). Unadjusted odds for having fibromyalgia was higher for Giardia exposed compared to controls (odds ratio (OR): 2.91, 95% confidence interval (CI): 1.72, 4.91), but adjusted for IBS and CF it was not (OR: 1.05, 95% CI: 0.57, 1.95). Among participants without CF the odds for fibromyalgia was 6.27 times higher for participants with IBS than those without (95% CI: 3.31, 11.91) regardless of exposure. Among participants without IBS the odds for fibromyalgia was 4.80 times higher for those with CF than those without (95% CI: 2.75, 8.37). CONCLUSIONS: We found a higher prevalence of fibromyalgia among Giardia exposed compared to controls 10 years after the acute infection. Fibromyalgia was strongly associated with IBS and CF, and the difference between the exposed and controls can be attributed to the high prevalence of IBS and CF among the Giardia exposed. Notably, this study was not designed to establish causality between Giardia exposure and the outcomes.

Excessive daytime sleepiness, sleep need and insomnia 3 years after Giardia infection: a cohort study.

OBJECTIVE: To investigate whether prior infection with Giardia lamblia is associated with excessive daytime sleepiness, insomnia, and level of sleep need. DESIGN: A questionnaire was sent to all confirmed cases of giardiasis 3 years after the outbreak and a control group matched on age and gender. Associations were evaluated by use of multiple regression analysis. RESULTS: Excessive daytime sleepiness (score ≥11 on the Epworth Sleepiness Scale) was reported by 31.5% of the Giardia-exposed and 14.1% of the controls. In multivariate analysis, excessive daytime sleepiness was independently associated with Giardia exposure, with an adjusted odds ratio of 1.40 (95% confidence interval [CI], 1.06-1.86). Insomnia was reported by 15.4% of Giardia-exposed and 8.8% of controls, adjusted odds ratio was 0.93 (95% CI, 0.65-1.35). Mean (SD) self-reported sleep need was 8 (1.4) hours among Giardia-exposed and 7.5 (1.1) hours in the control group (P < .001). The adjusted regression coefficient was 0.12 (95% CI, 0.01-0.24). CONCLUSION: Being exposed to Giardia was independently associated with excessive daytime sleepiness and larger sleep need, but not with insomnia.

The impact of atopic disease on the risk of post-infectious fatigue and irritable bowel syndrome 3 years after Giardia infection. A historic cohort study.

OBJECTIVE: To investigate whether atopic disease influences the prevalence of irritable bowel syndrome (IBS) and chronic fatigue (CF) after giardiasis. METHODS: A questionnaire was sent to all confirmed cases of giardiasis after a Norwegian outbreak, with response rate of 65.3% (817/1252). Controls were randomly selected matched on age and sex, with response rate of 31.4% (1128/3598). Associations were evaluated by use of logistic regression analyses. RESULTS: In the Giardia exposed group, 47.8% of those with asthma had IBS compared with 45.3% in those without asthma (p = 0.662). For controls, corresponding percentages were 23.9% and 12.2% (p < 0.001). Among those with asthma, the adjusted relative risk (RR) for IBS was 2.03 (95% confidence interval (CI): 1.45, 2.62) for the exposed group compared with controls. In those without asthma, the corresponding RR was 3.80 (95% CI: 3.30, 4.32). In the exposed group, 51.5% of those with asthma had CF compared with 44.9% in those without asthma (p = 0.218). For controls, corresponding percentages were 19.3% and 10.7% (p = 0.004). Among those with asthma, the adjusted RR for CF was 2.73 (95% CI: 1.98, 3.45) for the exposed compared with controls. In those without asthma, the corresponding RR for CF was 4.25 (95% CI: 3.66, 4.85). CONCLUSION: For the exposed, having asthma or allergy did not increase the outcome of IBS or CF. For the control group, having an atopic disease made a substantial risk difference, with significantly more IBS and CF.