Efficacy and Safety of Ascending Doses of Arpraziquantel in Children Infected With Opisthorchis Viverrini

Inclusion Criteria: * Aged 2 to 7 years (i.e., 24 to 95 months). * Bodyweight ≥ 10.0 kg * Written informed consent signed by parents/caregivers (signature or thumbprint). * Agree to comply with study procedures, including provision of two stool samples at baseline and at follow-up assessment 14-21 days after treatment, respectively. * Willing to be examined by a study physician prior to treatment. * At least two slides of the quadruple Kato-Katz thick smears positive for O. viverrini. Exclusion Criteria: * Presence or signs of major systemic illness, e.g. severe anaemia (haemoglobin level of \< 80 g/L according to WHO) upon initial clinical assessment. * Known or suspected infection with Taenia solium (cysticercosis). * Known or suspected acute schistosomiasis. * Abnormal liver and kidney function. * Use of anthelminthic drugs within 4 weeks before or during study period. * Being breastfed. * Known allergy to study medications (i.e. praziquantel or any of the excipients). * Being prescribed or taking concomitantly medication with known contraindication or drug interactions with the study medication. * Concurrent participation in other clinical trials.