Efficacy and safety of praziquantel treatment against Schistosoma mansoni infection among pre-school age children in southern Ethiopia.

Background: Preventive chemotherapy with a single dose of praziquantel given to an all-at-risk population through mass drug administration is the cornerstone intervention to control and eliminate schistosomiasis as a public health problem. This intervention mainly targets school age children, and pre-school age children (pre-SAC) are excluded from receiving preventive chemotherapy, partly due to scarcity of data on praziquantel treatment outcomes.

Methods: We conducted active efficacy and safety surveillance of praziquantel treatment among 240 Schistosoma mansoni-infected pre-SAC who received a single dose of praziquantel (40 mg/kg) in southern Ethiopia. The study outcomes were egg reduction rates (ERR) and cure rates (CRs) four weeks after treatment using the Kato-Katz technique and treatment-associated adverse events (AEs) that occurred within 8 days post-treatment.

Results: The overall ERR was 93.3% (WHO reference threshold ≥ 90%), while the CR was 85.2% (95% CI = 80.0-89.5%). Baseline S. mansoni infection intensity was significantly associated with CRs, 100% among light infected than moderate (83.4%) or heavy (29.4%) infected children. An increase of 100 in baseline S. mansoni egg count per gram of stool resulted in a 26% (95% CI: 17%, 34%) reduction in the odds of cure. The incidence of experiencing at least one type of AE was 23.1% (95% CI: 18.0%, 29.0%). Stomachache, diarrhea, and nausea were the most common AEs. AEs were mild-to-moderate grade and transient. Pre-treatment moderate (ARR = 3.2, 95% CI: 1.69, 6.14) or heavy infection intensity (ARR = 6.5, 95% CI: 3.62, 11.52) was a significant predictor of AEs (p < 0.001). Sex, age, or soil-transmitted helminth coinfections were not significant predictors of CR or AEs.

Conclusions: Single-dose praziquantel is tolerable and effective against S. mansoni infection among pre-SAC, and associated AEs are mostly mild-to-moderate and transient. However, the reduced CR in heavily infected and AEs in one-fourth of S. mansoni-infected pre-SAC underscores the need for safety and efficacy monitoring, especially in moderate-to-high infection settings. Integrating pre-SACs in the national deworming programs is recommended to accelerate the elimination of schistosomiasis as a public health problem.