Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA.
BMC Infect Dis. 2010 Mar 6;10:51. doi: 10.1186/1471-2334-10-51.
The spatio-temporal patterns of infectious diseases that are environmentally driven reflect the combined effects of transmission dynamics and environmental heterogeneity. They contain important information on different routes of transmission, including the role of environmental reservoirs. Consideration of the spatial component in infectious disease dynamics has led to insights on the propagation of fronts at the level of counties in rabies in the US, and the metapopulation behavior at the level of cities in childhood diseases such as measles in the UK, both at relatively coarse scales. As epidemiological data on individual infections become available, spatio-temporal patterns can be examined at higher resolutions.
The extensive spatio-temporal data set for cholera in Matlab, Bangladesh, maps the individual location of cases from 1983 to 2003. This unique record allows us to examine the spatial structure of cholera outbreaks, to address the role of primary transmission, occurring from an aquatic reservoir to the human host, and that of secondary transmission, involving a feedback between current and past levels of infection. We use Ripley's K and L indices and bootstrapping methods to evaluate the occurrence of spatial clustering in the cases during outbreaks using different temporal windows. The spatial location of cases was also confronted against the spatial location of water sources.
Spatial clustering of cholera cases was detected at different temporal and spatial scales. Cases relative to water sources also exhibit spatial clustering.
The clustering of cases supports an important role of secondary transmission in the dynamics of cholera epidemics in Matlab, Bangladesh. The spatial clustering of cases relative to water sources, and its timing, suggests an effective role of water reservoirs during the onset of cholera outbreaks. Once primary transmission has initiated an outbreak, secondary transmission takes over and plays a fundamental role in shaping the epidemics in this endemic area.
受环境驱动的传染病时空模式反映了传播动力学和环境异质性的综合影响。它们包含了有关不同传播途径的重要信息，包括环境储库的作用。在传染病动力学中考虑空间因素，可以深入了解美国狂犬病中县一级传播前沿的传播情况，以及英国儿童疾病（如麻疹）中城市一级的复种群行为，这些都是在相对粗糙的尺度上进行的。随着个体感染的流行病学数据的出现，时空模式可以在更高的分辨率下进行检查。
孟加拉国 Matlab 的霍乱广泛时空数据集，记录了 1983 年至 2003 年的病例的个体位置。这一独特的记录使我们能够检查霍乱暴发的空间结构，解决原发性传播的作用，即从水生储库传播到人类宿主，以及继发性传播的作用，涉及当前和过去感染水平之间的反馈。我们使用 Ripley 的 K 和 L 指数和自举方法，使用不同的时间窗口评估暴发期间病例的空间聚类的发生。病例的空间位置也与水源的空间位置相对照。
在不同的时间和空间尺度上检测到霍乱病例的空间聚类。相对于水源的病例也表现出空间聚类。
病例的聚类支持了继发性传播在孟加拉国 Matlab 霍乱流行中的动态中起着重要作用。相对于水源的病例的空间聚类及其时间，表明在霍乱暴发开始时，水源储库具有有效作用。一旦原发性传播引发了暴发，继发性传播就会接管并在这个流行地区的疫情中发挥基础性作用。
