Spatio-temporally explicit estimation of R0 for pathogens with environmentally-mediated transmission

 描述(申请人提供)：间接病原体传播可以是媒介传播或环境媒介传播。后者是野生动物和家畜中一些重要的多宿主疾病的主要感染方式，包括几种人畜共患病(蔓延到人类的疾病)，并明确与宿主移动和在环境水库中保持病原体的地区的觅食有关。在这样的系统中计算R0需要我们估计每个水库对新病例的贡献。要做到这一点，我们必须将传播过程分解为病原体脱落、环境持久性和宿主接触(病原体摄入或吸入)成分。这种接触率可以由当地宿主移动和由更大规模的季节性资源选择驱动的觅食模式的组合来表征。持久性环境病原菌水库可被模拟为个体的局部感染区，具有其自身的人口学和空间分布特征，这些感染区的生活史影响着寄主的局部觅食。在这个为期4年的EEID项目中，我们提供了一种新的地理空间和数学相结合的方法来估计环境传播的R0。然后，我们将评估影响传播过程不同组成部分的控制策略的有效性。为此，我们提出了以下具体目标：具体目标1：通过量化宿主运动和觅食行为、描述局部感染区的空间分布和人口学特征、描述控制宿主觅食和病原体持久性的环境因素，导出描述宿主与局部感染区的特定接触率的函数；具体目标2：应用这些函数来估计炭疽病(炭疽芽孢杆菌间接传播)的R0，使用来自两个炭疽活跃地区的经验数据集，在有和没有疾病控制的自由范围的草食动物对比系统中；具体目标3：评估我们新的R0估计与野生动物和牲畜系统的疾病控制战略相关的概念和实践影响，包括那些人类疾病仍然是主要威胁的系统。

 DESCRIPTION (provided by applicant): Indirect pathogen transmission can be vectored or environmentally-mediated. The latter is the primary mode of infection for a number of important multi-host diseases in wildlife and livestock, including several zoonoses (diseases that spillover into humans) and is explicitly linked to host movements and foraging in areas where the pathogen is maintained in environmental reservoirs. Calculating R0 in such systems requires that we estimate the contribution of each reservoir to new cases. To do this we must unpack the transmission process into its pathogen shedding, environmental persistence, and host contact (pathogen ingestion or inhalation) components. Such contact rates can be characterized from a combination of local host movement and foraging patterns driven by larger-scale seasonal resource selection. Persistent environmental pathogen reservoirs can be modeled as individual, local infectious zones with their own demography and spatial distribution; life history of these zones influence host foraging locally. In this 4-year EEID project, we provide a novel combined geospatial and mathematical approach for estimating R0 for environmentally-mediated transmission. We will then assess efficacies of control strategies impacting different components of the transmission process. Toward this, we propose the following specific aims: Specific Aim 1: Derive functions to describe host-specific contact rates with local infectious zones by quantifying host movement and foraging behavior, characterizing the spatial distribution and demography of local infectious zones, characterizing the environmental factors controlling host foraging and pathogen persistence; Specific Aim 2: Apply these functions to estimating R0 for anthrax (indirect transmission of Bacillus anthracis) using empirical datasets from two regions with active anthrax in free ranging herbivores-contrasting systems with and without disease control; Specific Aim 3: Evaluate the conceptual and practical impact of our novel R0 estimates as related to disease control strategies for wildlife and livestock systems, including those where human disease remains a major threat.