Davis Arbovirus Research and Training Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, United States.
Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States; Arboviral Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, United States.
Epidemics. 2023 Sep;44:100697. doi: 10.1016/j.epidem.2023.100697. Epub 2023 Jun 16.
Ivermectin (IVM)-treated birds provide the potential for targeted control of Culex mosquitoes to reduce West Nile virus (WNV) transmission. Ingestion of IVM increases mosquito mortality, which could reduce WNV transmission from birds to humans and in enzootic maintenance cycles affecting predominantly bird-feeding mosquitoes and from birds to humans. This strategy might also provide an alternative method for WNV control that is less hampered by insecticide resistance and the logistics of large-scale pesticide applications. Through a combination of field studies and modeling, we assessed the feasibility and impact of deploying IVM-treated birdfeed in residential neighborhoods to reduce WNV transmission. We first tracked 105 birds using radio telemetry and radio frequency identification to monitor their feeder usage and locations of nocturnal roosts in relation to five feeder sites in a neighborhood in Fort Collins, Colorado. Using these results, we then modified a compartmental model of WNV transmission to account for the impact of IVM on mosquito mortality and spatial movement of birds and mosquitoes on the neighborhood level. We found that, while the number of treated lots in a neighborhood strongly influenced the total transmission potential, the arrangement of treated lots in a neighborhood had little effect. Increasing the proportion of treated birds, regardless of the WNV competency status, resulted in a larger reduction in infection dynamics than only treating competent birds. Taken together, model results indicate that deployment of IVM-treated feeders could reduce local transmission throughout the WNV season, including reducing the enzootic transmission prior to the onset of human infections, with high spatial coverage and rates of IVM-induced mortality in mosquitoes. To improve predictions, more work is needed to refine estimates of daily mosquito movement in urban areas and rates of IVM-induced mortality. Our results can guide future field trials of this control strategy.
伊维菌素（IVM）处理过的鸟类为靶向控制库蚊以减少西尼罗河病毒（WNV）传播提供了潜力。摄入伊维菌素会增加蚊子的死亡率，从而减少鸟类向人类传播和在以鸟类为主要食源的蚊媒维持循环中传播的WNV。这种策略也可能为控制 WNV 提供一种替代方法，较少受到杀虫剂抗性和大规模施药的后勤限制。通过野外研究和建模的结合，我们评估了在居民区部署经伊维菌素处理的鸟食以减少 WNV 传播的可行性和影响。我们首先使用无线电遥测和射频识别跟踪了 105 只鸟类，以监测它们对五个喂食器的使用情况以及夜间栖息地的位置，这些喂食器位于科罗拉多州柯林斯堡的一个居民区。根据这些结果，我们随后修改了WNV 传播的隔室模型，以考虑 IVM 对蚊子死亡率和鸟类和蚊子在社区层面上的空间运动的影响。我们发现，虽然居民区中经处理的地段数量强烈影响了总传播潜力，但居民区中经处理的地段的排列方式影响很小。无论 WNV 效力状态如何，增加经处理的鸟类比例都会导致感染动态的更大减少，而不仅仅是治疗有能力的鸟类。总之，模型结果表明，部署经伊维菌素处理的饲料可以减少整个 WNV 季节的局部传播，包括在人类感染开始之前减少地方性传播，具有高空间覆盖率和蚊子中 IVM 诱导死亡率。为了改进预测，需要进一步开展工作，以完善城市地区蚊子每日运动和 IVM 诱导死亡率的估计。我们的研究结果可以为该控制策略的未来现场试验提供指导。
