Quantitative Disease Ecology and Conservation (QDEC) Lab, Department of Geography, University of Florida, Gainesville, FL, 32611, USA.
Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32610, USA.
Malar J. 2020 Sep 4;19(1):326. doi: 10.1186/s12936-020-03398-z.
Indoor residual spraying (IRS) is an effective method to control malaria-transmitting Anopheles mosquitoes and often complements insecticide-treated mosquito nets, the predominant malaria vector control intervention. With insufficient funds to cover every household, malaria control programs must balance the malaria risk to a particular human community against the financial cost of spraying that community. This study creates a framework for modelling the distance to households for targeting IRS implementation, and applies it to potential risk prioritization strategies in four provinces (Luapula, Muchinga, Eastern, and Northern) in Zambia.
Optimal network models were used to assess the travel distance of routes between operations bases and human communities identified through remote sensing. Network travel distances were compared to Euclidean distances, to demonstrate the importance of accounting for road routes. The distance to reaching communities for different risk prioritization strategies were then compared assuming sufficient funds to spray 50% of households, using four underlying malarial risk maps: (a) predicted Plasmodium falciparum parasite rate in 2-10 years olds (PfPR), or (b) predicted probability of the presence of each of three main malaria transmitting anopheline vectors (Anopheles arabiensis, Anopheles funestus, Anopheles gambiae).
The estimated one-way network route distance to reach communities to deliver IRS ranged from 0.05 to 115.69 km. Euclidean distance over and under-estimated these routes by - 101.21 to 41.79 km per trip, as compared to the network route method. There was little overlap between risk map prioritization strategies, both at a district-by-district scale, and across all four provinces. At both scales, agreement for inclusion or exclusion from IRS across all four prioritization strategies occurred in less than 10% of houses. The distances to reaching prioritized communities were either lower, or not statistically different from non-prioritized communities, at both scales of strategy.
Variation in distance to targeted communities differed depending on risk prioritization strategy used, and higher risk prioritization did not necessarily translate into greater distances in reaching a human community. These findings from Zambia suggest that areas with higher malaria burden may not necessarily be more remote than areas with lower malaria burden.
室内滞留喷洒（IRS）是控制传播疟疾的按蚊的有效方法，通常是杀虫剂处理过的蚊帐的补充，是主要的疟疾媒介控制干预措施。由于资金不足，无法覆盖每个家庭，疟疾控制规划必须在特定人类社区的疟疾风险与喷洒该社区的财务成本之间取得平衡。本研究创建了一个框架，用于为针对 IRS 实施的家庭目标距离建模，并将其应用于赞比亚四个省（卢阿普拉、穆钦加、东方和北方）的潜在风险优先排序策略。
使用最优网络模型来评估通过遥感确定的操作基地和人类社区之间的行程的旅行距离。比较了网络旅行距离和欧几里得距离，以证明考虑道路路线的重要性。然后，根据假设有足够的资金喷洒 50%的家庭，使用四种潜在的疟疾风险图，比较了不同风险优先排序策略到达社区的距离：（a）2-10 岁儿童中预测的恶性疟原虫寄生虫率（PfPR），或（b）三种主要疟疾传播按蚊（阿比西尼亚按蚊、冈比亚按蚊、芬尼斯按蚊）存在的预测概率。
到达社区提供 IRS 的单程网络路线距离估计为 0.05 至 115.69 公里。与网络路线方法相比，欧几里得距离每趟旅行低估或高估了这些路线 -101.21 至 41.79 公里。在区一级和四个省一级，风险图优先排序策略之间的重叠都很少。在这两个尺度上，对于所有四个优先排序策略，纳入或排除 IRS 的房屋不到 10%。在两个尺度上，优先社区的到达距离要么较低，要么与非优先社区在统计学上没有差异。
目标社区的距离差异取决于使用的风险优先排序策略，较高的风险优先排序不一定意味着到达人类社区的距离更大。赞比亚的这些发现表明，疟疾负担较高的地区不一定比疟疾负担较低的地区更偏远。
