Dissertation Research: The Dynamics of Disease Spread by Ectoparasites

Kareiva 9321590除了少数例外，蜱虫传播的疾病在野生动物种群中维持，而不是在人类种群中。跳蚤传播的疾病也有类似的生物学现象；例如，在没有人类参与的情况下，鼠疫在野生啮齿动物种群中得以维持。也许是因为这些疾病是在野生动物种群中而不是在人类种群中维持的，所以关于这些疾病的动态以及影响疾病动态的跳蚤或蜱虫行为的研究很少。相比之下，人类传染病动力学的研究历史悠久。然而，这项工作的大部分假设是，疾病的传播是通过受感染和易感个体的随机混合发生的。一般来说，这并不是对动物行为的准确描述，而且它可能特别不适合描述由外寄生虫传播的疾病的传播（寄生虫，如生活在宿主外部的跳蚤和蜱虫）。本研究项目结合实验和理论方法来研究外寄生虫行为对这些寄生虫传播疾病动力学的影响。本项目研究系统为华盛顿州西部的一种啮齿动物Neotoma cinerea，蚤类Orchopeas sexdentatus和anomiopsilus amphibolus，以及硬蜱Ixodes angustus。这项工作包括观察跳蚤和蜱在啮齿动物种群中的运动，并将观察到的行为纳入理论模型，以预测对疾病动力学的影响。实地数据和理论研究的综合在流行病学中特别重要，因为人们经常想要确定定量属性，例如疾病传播的阈值。通过将实地研究与理论模型相结合，本工作力求建立切合实际的模型，并对强烈影响疾病是否为流行病和疾病是否为空间分布的因素的数值进行估计。

Kareiva 9321590 With few exceptions, diseases which are spread by ticks are maintained within wildlife populations, not human populations. A similar biology is seen for flea-borne diseases; for example, plague is maintained in wild rodent populations without the involvement of humans. Perhaps because these diseases are maintained in wildlife populations instead of human populations, little work has been done on the dynamics of these diseases and the flea or tick behaviors that influence the disease dynamics. In comparison, there is long history of work on the dynamics of human infectious diseases. Much of this work, however, assumes that transmission of disease occurs via random mixing of infected and susceptible individuals. In general this is not an accurate description of animal behavior, and it may be particularly inappropriate for describing the transmission of diseases spread by ectoparasites ( parasites, such as fleas and ticks that live on the exterior of their hosts). This research project combines both experimental and theoretical approaches to examine the effect of ectoparasite behavior on the dynamics of diseases spread by these parasites. The study system for this project is a species of rodent, Neotoma cinerea, the fleas, Orchopeas sexdentatus and Anomiopsyllus amphibolus, and the hard tick, Ixodes angustus in Western Washington. The work involves observations of flea and tick movement within the rodent populations and incorporates the observed behaviors into theoretical models to predict the effects on disease dynamics. The synthesis of field data and theoretical studies is especially important in epidemiology, because one often wants to identify quantitative attributes, such as thresholds for the spread of disease. By combining field studies with theoretical models, this work seeks to develop realistic models and estimates of numerical values of factors that strongly influence whether the disease is epidemic and the disease is spatial distribution.