Evaluation of praziquantel efficacy in children after two decades of mass distribution in Bamako, Mali

Introduction: Schistosomiasis, a neglected tropical disease, remains endemic in Mali despite ongoing preventive chemotherapy with praziquantel (PZQ). This study aimed to assess the therapeutic efficacy of PZQ against Schistosoma haematobium and S. mansoni infections in school-aged children residing in urban and peri-urban areas of the Bamako district. Methods: A prospective cohort study was conducted between April and May 2023 among children aged 6 to 14 years who tested positive for schistosomiasis, recruited from an epidemiological survey involving 736 children. Data on sociodemographic, socioeconomic, clinical, and parasitological variables were collected at baseline (Day 0) and 14 days after PZQ treatment. Treatment was administered on Day 0 according to WHO recommendations (40 mg/kg). Parasitological diagnosis was performed using the urine filtration technique for S. haematobium and the Kato-Katz method for S. mansoni at both Day 0 and Day 14. Treatment efficacy was assessed using the cure rate (CR) and the egg reduction rate (ERR). Results: A total of 99 children infected with schistosomiasis were followed up, including 77 children positive for S. haematobium, 35 for S. mansoni, and 13 who were co-infected. Among these 99 children, 82.8% resided in Taliko and 17.2% in Missabougou. Most Taliko children lived within 500 meters of the Woyowayanko River and had frequent contact with it. The overall CR for S. haematobium was 80.5%, with an ERR of 87.3%. In Taliko, the highest ERR (79.4%) was observed among children with low parasite burden, while in Missabougou, all children with low infection intensity were egg-negative two weeks after treatment. Conclusion: The 14-day follow-up was chosen in accordance with WHO recommendations for assessing short-term efficacy and egg clearance after praziquantel (PZQ) treatment. Although the results suggest a reduction in infection levels among treated children, the limited follow-up period does not allow firm conclusions on long-term efficacy or reinfection dynamics. The relatively lower cure and egg reduction rates observed in some subgroups may indicate the need for extended follow-up and sustained monitoring, as well as targeted interventions such as health education and community engagement—to enhance schistosomiasis control and elimination outcomes.