Mduluza Takafira, Zdesenko Grace, Tagwireyi Paradzayi, Jones Caitlin M, Mutapi Francisca
Department of Biochemistry, University of Zimbabwe, Mount Pleasant, Harare, Zimbabwe.
Tackling Infections to Benefit Africa (TIBA) Partnership, Ashworth Laboratories, King's Buildings, University of Edinburgh, Edinburgh, United Kingdom.
PLoS Negl Trop Dis. 2025 Sep 24;19(9):e0013546. doi: 10.1371/journal.pntd.0013546. eCollection 2025 Sep.
Urogenital schistosomiasis is contracted from the Schistosoma haematobium parasite and is treated with the drug praziquantel (PZQ). Despite MDA interventions, persistent hotspots (PHS) of S. haematobium infection have been identified in multiple schistosome endemic African countries but have yet to be characterised in Zimbabwe. This study assessed long-term infection persistence and variability in praziquantel (PZQ) efficacy among school-aged children (6-15 years) in 29 districts of Zimbabwe, using data from MDAs conducted between 2012 and 2017. Metrics included infection prevalence, mean egg count, and treatment efficacy indicators. Two hotspot definitions were applied: (i) prevalence-based persistent hotspots (PPHS), identified by limited reduction or rebound in prevalence; and (ii) efficacy-based persistent hotspots (EPHS), defined by cure rates below 70%. Statistical comparisons between hotspot and non-hotspot ("responder") districts used regression models, Fisher's exact test and Mann-Whitney U tests. Analyses revealed four PPHS and six EPHS. PPHS districts exhibited significantly higher baseline prevalence and infection intensity compared with responders (P = 0.043), a pattern not observed for EPHS. Greater distance from freshwater sources was associated with EPHS occurrence (P = 0.016), although this appeared to be an indirect effect of initially high infection intensities. Lower treatment frequency correlated with increased hotspot occurrence, but the relationship was not statistically significant for either hotspot category. Other investigated factors including treatment coverage, timing of drug administration and ecological suitability for intermediate host snails showed no significant association with hotspot status. The elevated initial prevalence and infection intensity in PPHS suggest these indicators could be used for early hotspot identification, enabling targeted adjustments in intervention strategies. The findings underscore the limitations of relying solely on preventive chemotherapy in high-transmission settings. Integrating complementary measures such as water, sanitation and hygiene (WASH) interventions and snail control may improve outcomes, particularly in hotspot areas. In conclusion, the persistence of S. haematobium hotspots in Zimbabwe highlights the need for adaptive, integrated control approaches aligned with the WHO's 2030 roadmap. Monitoring baseline epidemiological indicators could facilitate earlier detection of persistent transmission foci, guiding more effective and sustainable schistosomiasis control.
泌尿生殖系统血吸虫病是由埃及血吸虫寄生虫感染所致，可用吡喹酮（PZQ）进行治疗。尽管开展了大规模药物驱虫（MDA）干预措施，但在多个非洲血吸虫病流行国家已发现埃及血吸虫感染的持续热点地区（PHS），而津巴布韦尚未对这些地区进行特征描述。本研究利用2012年至2017年期间开展的MDA数据，评估了津巴布韦29个地区学龄儿童（6至15岁）的长期感染持续性以及吡喹酮（PZQ）疗效的变异性。评估指标包括感染率、平均虫卵计数和治疗效果指标。应用了两种热点地区定义：（i）基于患病率的持续热点地区（PPHS），通过患病率降低有限或反弹来确定；（ii）基于疗效的持续热点地区（EPHS），定义为治愈率低于70%。热点地区和非热点地区（“反应者”）之间的统计比较采用回归模型、Fisher精确检验和Mann-Whitney U检验。分析发现了4个PPHS和6个EPHS。与反应者相比，PPHS地区的基线患病率和感染强度显著更高（P = 0.043），EPHS地区未观察到这种模式。距离淡水水源较远与EPHS的出现相关（P = 0.016），尽管这似乎是最初高感染强度的间接影响。较低的治疗频率与热点地区发生率增加相关，但对于任何一种热点地区类别，这种关系在统计学上均不显著。其他调查因素，包括治疗覆盖率、药物给药时间和中间宿主螺的生态适宜性，与热点地区状况均无显著关联。PPHS地区较高的初始患病率和感染强度表明，这些指标可用于早期热点地区识别，从而有针对性地调整干预策略。研究结果强调了在高传播环境中仅依靠预防性化疗的局限性。整合水、环境卫生和个人卫生（WASH）干预措施及灭螺等补充措施可能会改善结果，特别是在热点地区。总之，津巴布韦埃及血吸虫热点地区的持续存在凸显了需要采取与世界卫生组织2030年路线图相一致的适应性综合控制方法。监测基线流行病学指标有助于更早发现持续传播病灶，指导更有效和可持续的血吸虫病控制。
