Study recruitment base and participants. Participants were recruited based on a mailed questionnaire study regarding fatigue  and abdominal complaints  to all individuals with outbreak related laboratory confirmed giardiasis . Five years after the outbreak, patients who reported chronic fatigue in this questionnaire were invited to participate in a thorough clinical evaluation and screening. Fifty three individuals agreed to participate. Five patients were excluded from this study after evaluation. Two control groups were recruited; 22 individuals with normal score (=11) in the questionnaire three years after, and 10 healthy individuals not affected by the outbreak (unexposed controls) and without particular abdominal symptoms or fatigue.
Hanevik et al. BMC Infectious Diseases 2012 12:258 doi:10.1186/1471-2334-12-258