Lutambi Angelina Mageni, Chitnis Nakul, Briët Olivier J T, Smith Thomas A, Penny Melissa A
Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland; Ifakara Health Institute, Dar es Salaam, Tanzania.
Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland; Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.
PLoS One. 2014 May 13;9(5):e97065. doi: 10.1371/journal.pone.0097065. eCollection 2014.
Vector control interventions have resulted in considerable reductions in malaria morbidity and mortality. When universal coverage cannot be achieved for financial or logistical reasons, the spatial arrangement of vector control is potentially important for optimizing benefits. This study investigated the effect of spatial clustering of vector control interventions on reducing the population of biting mosquitoes. A discrete-space continuous-time mathematical model of mosquito population dynamics and dispersal was extended to incorporate vector control interventions of insecticide treated bednets (ITNs), Indoor residual Spraying (IRS), and larviciding. Simulations were run at varying levels of coverage and degree of spatial clustering. At medium to high coverage levels of each of the interventions or in combination was more effective to spatially spread these interventions than to cluster them. Suggesting that when financial resources are limited, unclustered distribution of these interventions is more effective. Although it is often stated that locally high coverage is needed to achieve a community effect of ITNs or IRS, our results suggest that if the coverage of ITNs or IRS are insufficient to achieve universal coverage, and there is no targeting of high risk areas, the overall effects on mosquito densities are much greater if they are distributed in an unclustered way, rather than clustered in specific localities. Also, given that interventions are often delivered preferentially to accessible areas, and are therefore clustered, our model results show this may be inefficient. This study provides evidence that the effectiveness of an intervention can be highly dependent on its spatial distribution. Vector control plans should consider the spatial arrangement of any intervention package to ensure effectiveness is maximized.
病媒控制干预措施已使疟疾发病率和死亡率大幅降低。由于财政或后勤原因无法实现普遍覆盖时，病媒控制的空间布局对于优化效益可能至关重要。本研究调查了病媒控制干预措施的空间聚集对减少叮咬蚊虫数量的影响。扩展了一个关于蚊虫种群动态和扩散的离散空间连续时间数学模型，以纳入经杀虫剂处理的蚊帐（ITN）、室内滞留喷洒（IRS）和杀幼虫剂等病媒控制干预措施。在不同覆盖水平和空间聚集程度下进行了模拟。在每种干预措施或多种干预措施组合达到中高覆盖水平时，在空间上分散这些干预措施比将它们聚集起来更有效。这表明当财政资源有限时，这些干预措施的非聚集分布更有效。尽管人们常说需要在当地实现高覆盖率才能产生蚊帐或室内滞留喷洒的社区效果，但我们的结果表明，如果蚊帐或室内滞留喷洒的覆盖率不足以实现普遍覆盖，且没有针对高风险地区，那么以非聚集方式分布对蚊虫密度的总体影响要比在特定地点聚集分布大得多。此外，鉴于干预措施通常优先提供给易到达的地区，因此会出现聚集情况，我们的模型结果表明这可能效率低下。本研究提供了证据，证明一项干预措施的有效性可能高度依赖于其空间分布。病媒控制计划应考虑任何一套干预措施的空间布局，以确保效益最大化。
