Lakwo Thomson Luroni, Siewe Fodjo Joseph, Jada Stephen Raimon, Alinda Peter, Tionga Moses, Marcello Constantino Doggale Remijo, War Deng Gai Dual, Saleeb Marina, Colebunders Robert
Ministry of Health, Vector Control Division, Kampala, Uganda.
Global Health Institute, University of Antwerp, Antwerp, Belgium.
PLoS Negl Trop Dis. 2025 Jul 23;19(7):e0013309. doi: 10.1371/journal.pntd.0013309. eCollection 2025 Jul.
Despite several rounds of ivermectin treatment, onchocerciasis transmission persists in Mvolo and Mundri West Counties (Western Equatoria State, South Sudan). A community-based "Slash and clear" (S&C) vector control method was recently introduced, but its effectiveness remains unclear.
Between October 2023 and November 2024, entomological studies were conducted to map blackfly breeding sites along River Naam (Mvolo County) and River Yei (Mundri West County). Following baseline assessment of daily biting rates at multiple catching sites, one round of S&C was implemented at selected intervention sites. Monthly biting rates (MBR) were monitored over a follow-up period of 8-14 months and compared between intervention and control sites.
Thirteen breeding sites of Simulium damnosum, sensu lato. were found on the Naam and Yei Rivers. Biting rates were consistently higher during the rainy season than the dry season across both Counties. On the Naam River (14 months of follow-up), Mann-Kendall trend tests showed non-significant reductions in MBRs at both intervention (tau = -0.038, p-value = 0.881) and control sites (tau = -0.135, p-value = 0.313). Similar non-significant changes were observed on the Yei River (8 months follow-up), with tau = 0.046 (p-value = 0.820) and tau = 0.163 (p-value = 0.363) for intervention and control sites, respectively. Generalized additive models (GAM) regression analysis indicated that seasonality was the only significant predictor of MBR, with increased biting rates during the rainy season (p < 0.001). A single round of S&C at baseline did not result in significant reductions in MBRs (p-value = 0.651 in Mvolo and p-value = 0.531 in Mundri West).
Blackfly biting rates in Mvolo and Mundri West Counties are strongly influenced by seasonal variations, peaking during the rainy season. Our findings indicate that a single round of S&C is insufficient to reduce blackfly biting in the medium term. Repeated and strategically timed annual implementation of S&C is likely required to achieve significant and lasting vector control impacts.
尽管进行了多轮伊维菌素治疗，但盘尾丝虫病传播仍在姆沃洛县和蒙德里西县（南苏丹西赤道州）持续存在。最近引入了一种基于社区的“砍伐清理”（S&C）病媒控制方法，但其有效性仍不明确。
在2023年10月至2024年11月期间，开展了昆虫学研究，以绘制纳姆河（姆沃洛县）和耶伊河（蒙德里西县）沿岸的蚋繁殖地地图。在对多个捕捉点的每日叮咬率进行基线评估后，在选定的干预点实施了一轮S&C。在8至14个月的随访期内监测每月叮咬率（MBR），并在干预点和对照点之间进行比较。
发现了13个广义的恶蚋繁殖地，位于纳姆河和耶伊河上。在两个县，雨季的叮咬率始终高于旱季。在纳姆河（随访14个月），曼-肯德尔趋势检验显示，干预点（tau = -0.038，p值 = 0.881）和对照点（tau = -0.135，p值 = 0.313）的MBR均无显著下降。在耶伊河（随访8个月）也观察到类似的无显著变化，干预点和对照点的tau分别为0.046（p值 = 0.820）和0.163（p值 = 0.363）。广义相加模型（GAM）回归分析表明，季节性是MBR的唯一显著预测因素，雨季叮咬率增加（p < 0.001）。基线时的一轮S&C并未导致MBR显著下降（姆沃洛县p值 = 0.651，蒙德里西县p值 = 0.531）。
姆沃洛县和蒙德里西县的蚋叮咬率受季节变化的强烈影响，在雨季达到峰值。我们的研究结果表明，一轮S&C不足以在中期减少蚋叮咬。可能需要每年重复并在战略时机实施S&C，以实现显著且持久的病媒控制效果。
