Impact of Targeted IRS and Population Movement on Malaria in Northern Zambia

 描述(申请人提供)：在撒哈拉以南非洲，恶性疟原虫引起的疟疾每年造成约564,000人死亡。在赞比亚，自2009年以来，每年的疟疾病例逐年增加，疟疾仍然是导致儿童死亡的最大单一原因。疟疾控制在北部省份尤其具有挑战性，那里5岁以下儿童的寄生虫流行率仍然超过50%，对拟除虫菊酯和氨基甲酸酯杀虫剂的抗药性普遍存在。有针对性的家庭室内滞留喷洒(IRS)是低资源环境下的一种新兴干预战略，重点放在人口密度较高的热点地区，以便将资源集中在对维持当地传播影响最大的家庭集群上。随着全球对有针对性的国税局的兴趣增加，需要进行评估，以确定这一战略在不同环境中的有效性。此外，人口流动被认为是疟疾传播的重要驱动力，但人们对人口流动如何影响个体疟疾风险或它可能如何影响定向干预战略的有效性知之甚少。2014年秋天，一次有针对性的 美国国税局在赞比亚卢阿普拉省恩切伦格区使用一种新型有机磷杀虫剂甲基嘧啶磷进行干预，这一战略预计将在2015年秋季重复。这项研究将有助于更好地了解赞比亚北部高负担环境下的疟疾传播动态，并将在疟疾全年传播、日常个人流动和季节性农业迁徙的背景下对这一干预战略进行严格评估。目标1将使用从4.5年积极监测中连续收集的横断面家庭调查，以评估定向国税局对恩切伦格区疟疾寄生虫流行的影响。单变量方法和多变量模型都将被用来确定这种干预在多年中的总影响、直接影响和间接影响。这将是第一项在高传播环境下评估有针对性的IRS策略有效性的研究，也是第一项在多个喷洒季节评估高传播环境下甲基嘧啶磷有效性的研究。目标2将使用2014年实施的一项为期一年的研究的数据，评估个人运动模式对30天疟疾风险的贡献，其中81人携带GPS数据记录器一个月，并确定了疟疾事件。描述性统计、多变量模型和空间统计将用于比较感染疟疾的人和未感染疟疾的人的运动模式。这项研究将首次描述疟疾高传播环境中的个体运动模式，并探索这些运动模式作为疟疾发病率的风险因素。这也将是评估个人行动对有针对性干预效果的影响的首批研究之一。这项提案的广泛、长期目标是指导撒哈拉以南非洲农村地区的疟疾控制战略。

 DESCRIPTION (provided by applicant): Malaria due to Plasmodium falciparum causes an estimated 564,000 deaths per year in sub-Saharan Africa. In Zambia, annual cases of malaria have increased every year since 2009, and malaria remains the single largest cause of child mortality. Malaria control is particularly challenging in the northern provinces, where parasite prevalence remains over 50% in children under 5 years, and resistance to pyrethroid and carbamate insecticides is widespread. Targeted household indoor residual spraying (IRS) is an emerging intervention strategy in low-resource settings that focuses on hotspots with high population density so resources can be concentrated on clusters of households that have the most impact in sustaining local transmission. As the global interest in targeted IRS increases, evaluations are needed to determine the effectiveness of this strategy in different settings. In addition, human population movement has been cited as an important driver of malaria transmission, but little is known about how movement affects individual malaria risk or how it might impact the effectiveness of a targeted intervention strategy. In the fall of 2014, a targeted IRS intervention was launched in Nchelenge District, Luapula Province, Zambia using a novel organophosphate insecticide pirimiphos-methyl, and this strategy is expected to be repeated in the fall of 2015. This research will contribute to better understanding the malaria transmission dynamics in a high burden setting in northern Zambia, and will provide a rigorous evaluation of this intervention strategy in the context of year-round malaria transmission, daily individual movement, and seasonal agricultural migration. Aim 1 will use serially collected cross-sectional household surveys from over 4.5 years of active surveillance to evaluate the impact of targeted IRS on malaria parasite prevalence in Nchelenge District. Both univariate methods and multivariate models will be used to determine the total, direct, and indirect effects of this intervention over multiple years. This will be the first study to assess the effectiveness of a targeted IRS strategy in a high transmission setting, and the first study to assess the effectiveness of pirimiphos-methyl in a high-transmission setting over multiple spray seasons. Aim 2 will evaluate the contribution of individual movement patterns to 30-day malaria risk using data from a year-long study implemented in 2014, in which 81 people carried a GPS data logger for one month, and incident malaria was identified. Descriptive statistics, multivariate models, and spatial statistics will be used to compare movement patterns of people who contracted malaria compared with those who did not. This research will be the first to describe individual movement patterns in a high malaria transmission setting and to explore these movement patterns as a risk factor for malaria incidence. This will also be among the first studies to evaluate the impact of individual human movement on the effectiveness of targeted interventions. The broad, long-term goals of this proposal are to guide malaria control strategies in rural sub-Saharan Africa.