A prospective analysis of clinical and parasitological outcomes after treatment or a wait-and-see approach of Dientamoeba fragilis infection in an adult general practice population.

Purpose: Dientamoeba fragilis is a protozoan frequently encountered in stool samples globally. It is debated whether Dientamoeba fragilis carries pathogenic capacities. This study prospectively analyses clinical and parasitological outcomes after treatment or a wait-and-see approach of Dientamoeba fragilis infection in a general practice adult population.

Methods: In this prospective observational cohort study 113 adult patients with a positive Polymerase Chain Reaction (PCR) test result for D. fragilis (T0) in a primary care setting, were followed-up longitudinally with a control PCR-test and microscopic stool examination at 30 days (T1) and 90 days (T2) after inclusion. Standardized patient-reported questionnaires including treatment details and the adjusted Irritable Bowel Syndrome-Severity Score (IBS-SS) were retrieved at T0, T1 and T2.

Results: Parasitology and questionnaires were retrieved from 87 participants at T0 and T1, and 74 at T2. Treated patients(n = 64) more often tested PCR negative at T1 (64.1% vs. 16.4%, p < 0.001) and T2 (67.3% vs. 5.3%, p < 0.001) compared to untreated patients. No difference in decline in IBS-SS was seen comparing the treatment and non-treatment groups at T1 (p = 0.403) or T2 (p = 1.00).

Conclusion: A short and long term increased parasitological clearance is shown with treatment of clioquinol or metronidazole compared with no treatment. A clear and significant correlation between parasitological cure and decline of clinical complaints as reported by the participants could not be established.