Ellis John R, Mutono Nyamai, Vasconcelos Andreia, Thumbi Samuel M, Hollingsworth T Déirdre, Anderson Roy M
Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, White City Campus, Imperial College London, London, United Kingdom.
Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya.
PLoS Negl Trop Dis. 2025 Jun 2;19(6):e0012624. doi: 10.1371/journal.pntd.0012624. eCollection 2025 Jun.
Schistosomiasis affects more than 230 million people worldwide. Control and elimination of this parasitic infection is based on mass drug administration of praziquantel (PZQ), which has been in use for several decades. Because of the limitations of the efficacy of PZQ especially against juvenile worms, and the threat of the emergence of resistance, there is a need to consider alternative formulations or delivery methods, or new drugs that could be more efficacious. We use an individual-based stochastic model of parasite transmission to investigate the effects of possible improvements to drug efficacy. We consider an increase in efficacy compared to PZQ, as well as additional efficacy against the juvenile life stage of schistosome parasites in the human host, and a slow-release formulation that would provide long-lasting efficacy for a period of time following treatment. Analyses suggest a drug with a high efficacy of 99%, or with efficacy lasting 24 weeks after treatment, are the two most effective individual improvements to the drug profile of PZQ. A drug with long lasting efficacy is most beneficial when MDA coverage is low. However, when prevalence of infection has already been reduced to a low level, a high efficacy is the most important factor to accelerate interruption of transmission. Our results indicate that increased efficacy against juvenile worms can only result in modest benefits, but the development of a new drug formulation with higher efficacy against adult worms or long-lasting efficacy would create an improvement to the community impact over the currently used formulation.
血吸虫病在全球影响着超过2.3亿人。对这种寄生虫感染的控制和消除基于吡喹酮（PZQ）的大规模药物施用，PZQ已使用数十年。由于PZQ功效的局限性，尤其是对幼虫的功效，以及耐药性出现的威胁，有必要考虑替代剂型或给药方法，或者更有效的新药。我们使用基于个体的寄生虫传播随机模型来研究药物疗效可能改善的影响。我们考虑与PZQ相比疗效的提高，以及对人体宿主中血吸虫寄生虫幼虫阶段的额外疗效，以及一种缓释制剂，该制剂在治疗后一段时间内将提供持久的疗效。分析表明，疗效高达99%的药物，或治疗后疗效持续24周的药物，是对PZQ药物特性最有效的两项单独改进。当群体药物施用覆盖率较低时，具有持久疗效的药物最为有益。然而，当感染率已降至较低水平时，高疗效是加速传播阻断的最重要因素。我们的结果表明，对幼虫疗效的提高只会带来适度的益处，但开发一种对成虫具有更高疗效或持久疗效的新药物制剂将对社区产生比目前使用的制剂更大的影响。
