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