ECOLOGY AND TRANSMISSION OF S.JAPONICUM: PHILIPPINES

这项提议的目的是建立一个动态模型，研究稻作引起的人为变化对菲律宾流行地区日本血吸虫传播的影响。该模型将包括几个物种、它们的种群生物学和行为，包括人类、蜗牛和日本血吸虫的动物宿主。我们将稻作及其时空变化及其对人类感染日本血吸虫的物理、水文和动物决定因素的多重影响定义为人为环境变化。该模型将能够预测水稻种植随时间和空间的变化而产生的人为环境变化对日本血吸虫传播给人类的潜在影响。水稻种植因素包括：水稻耕作方式的变化、农业推广和集约化；驯化的动物数量、传播行为和管理做法；用水和管理做法。开发可推广的血吸虫病向人类传播的预测生态模型是正在进行的制定具有成本效益和可接受的疾病控制战略的努力的基本组成部分。目前还没有发表日本血吸虫的模型，尽管对受感染的人进行了20年的治疗，但这种疾病在菲律宾和中国仍然是地方病。在最初12-18个月的时间里，确定了几个地点的传播平衡条件，并利用过去40年人、螺和动物感染的现有数据，我们将建立一个日本血吸虫的动态传播模型。然后，我们将治愈每个地点的所有人类，并观察18个月内人类感染日本血吸虫的发生率和强度。这将使统计分析能够确定特定传播因素与人类感染结果的关系。它还将允许更准确地构建日本血吸虫传播的年龄结构、种群动态模型，具有更好的可预测性和泛化能力。

The objective of this proposal is the development of a dynamic model of the influence of anthropogenic changes due to rice farming on the transmission of Schistosoma japonicum in the endemic areas of The Philippines. The model will include several species, their population biology and behavior, including humans, snails and animal reservoir hosts of S. japonicum. We define rice farming, its spatial and temporal variation and its multiple impacts on physical, hydrologic and animal determinants of human S. japonicum infection as anthropogenic environmental change. The model will allow the prediction of the potential effects of anthropogenic environmental changes stemming from variation in rice farming over time and space on the transmission of S. japonicum to humans. Rice farming factors include: variation in rice farming practices, agricultural expansion and intensification; domesticated animal numbers, transmission behaviors and management practices; water use and management practices. Developing generalizable predictive ecological models of schistosomiasis transmission to humans is a fundamental component of the ongoing effort to develop cost-effective and acceptable disease control strategies. There are at present no published models for S.japonicum, which remains endemic in The Philippines and China despite 20 years of treatment of infected humans. After an initial 12-18 month period of determining the equilibrium conditions of transmission in several sites, and use of extant data from the last 40 years on human, snail and animal infection we will develop a dynamic transmission model of S. japonicum. We will then cure all humans in each site and observe the incidence rate and intensity of S. japonicum infection in humans over 18 months. This will permit statistical analyses to determine the relationships of specific transmission factors to the outcome of human infection. It will also allow more accurate construction of an age- structured, population dynamic model of S. japonicum transmission with improved predictabilty and generalizability.