Treatment Study of Metronidazole to Treat Dientamoebiasis in Children

Inclusion Criteria: * Patients with samples investigated at Statens Serum Institut. * Faecal sample (index) positive for Dientamoeba fragilis (DF) by realtime PCR, within \< 7 days. * No faecal samples positive for DF within the period: 3 months prior to and up to index-sample. * Telephone interview to parents no later then 14 days after result from index-sample. * Age 3-12 years old. * Place of residence: Island of Zealand, incl. capital region. * Symptoms consistent with gastrointestinal infection of DF: Either 1) ≥ 2 episodes of diarrhea per week or 2) ≥ 2 episodes of stomach ache per week or 3) ≥ 2 of the following symptoms: Anorexia, Failure to thrive, Anal itching, excessive flatulence, other change in bowel movements. Exclusion Criteria: * Expected non-compliance. * Objection to subject participation from referring physician. * Underlying illness or comorbidity, incl. known gastrointestinal illness (both infectious and non-infectious), but excluding constipation. * Known liver disease or intolerance/allergy to metronidazole. * Positive screening for other intestinal pathogens, which may explain subject symptoms. * Treatment with metronidazole outside of study within study period. * Weight \> 50 kg