Doctoral Dissertation Improvement: Rodent-human Cohabitation and Disease Transfer in Sedentary Human Populations

人畜共患疾病是在人与其他动物之间传播的疾病，它们占人类所有传染病的一半以上。啮齿动物是这些人畜共患病最丰富的来源之一，但对于为什么啮齿动物对人类健康有如此大的影响，以及为什么一些啮齿动物物种容易传播这些疾病，而另一些啮齿动物物种不这样做，缺乏理论和经验上的解释。为了更好地了解人类与啮齿动物之间的流行病学关系，本论文的研究试图确定居住在人类家园及其周围的啮齿动物(在一种称为共生关系的生态关系中)是否比非共生的野生啮齿动物对人类健康构成更大的威胁。确定这一点后，研究小组将调查不同啮齿动物物种的行为和生态如何影响与人类共存模式的假说。这样做还可以让研究人员提出啮齿动物共生的潜在原因，无论是为了躲避和保护，还是为了获得食物。为了最大限度地提高数据的数量和质量，这项研究将专注于肯尼亚中部的农村人口，那里有20多种地方性啮齿动物与人类在同一栖息地重叠，并显示出不同程度的人畜共栖病原体感染。啮齿动物物种和病原体的多样性在美国是无与伦比的，它为确定共生性对疾病传播的普遍影响提供了一个理想的自然环境。为了确定由于共生关系造成的感染差异，这位博士生研究员(哈佛大学理查德·兰厄姆博士指导下的科林·麦凯布)将在家中和附近未受干扰的栖息地捕获啮齿动物。这些动物的血液将被提取，这些样本将被送往美国的实验室进行人畜共患病病原体检测。然后，研究人员将评估这些动物的冒险行为，还将评估它们的饮食，以确定这些啮齿动物与人类同居的最可能原因。通过确定自由生活的啮齿动物和人类之间的感染和接触模式，这项研究的结果将表明，野生啮齿动物或共生啮齿动物对人类构成更大的疾病风险，并通过了解影响共生的因素，公共卫生机构可以将控制努力集中在最有可能出现人与啮齿动物重叠的领域。在当今高度互联的世界中，新的疾病暴发引起的健康问题确实是全球性的。因此，通过促进对国外人畜共患病疫情的认识和控制，这项研究也将有助于美国的卫生安全。

Zoonotic diseases are those that are transmitted between humans and other animals, and they make up more than half of all infectious diseases in humans. Rodents are one of the richest sources of these zoonoses, yet both theoretical and empirical explanations are scant for why rodents have had such a great impact on human health and why some rodent species readily spread these diseases, while others do not. To better understand the epidemiological relationships that humans have with rodents, this dissertation research seeks to determine whether rodents that live in and around human homes (in an ecological relationship termed "commensalism") pose a greater threat to human health than wild rodents that are not commensal. After determining this, the research team will investigate hypotheses for how the behavior and ecology of different rodent species influence patterns of coexistence with humans. Doing so also will allow the researchers to propose an underlying cause for rodent commensalism, whether mainly for shelter and protection, or for access to food.In order to maximize both the quantity and quality of data, the research will focus on rural populations in central Kenya, where over twenty endemic rodent species overlap with humans in a single habitat and show varying degrees of infection with zoonotic pathogens. This diversity in rodent species and pathogens is unparalleled within the United States, and it provides an ideal natural setting in which to identify generalizable effects of commensalism on disease transmission. To determine differences in infection due to commensalism, the doctoral student researcher (Collin McCabe, under the supervision of Dr. Richard Wrangham, Harvard University) will capture rodents within homes and in nearby undisturbed habitats. Blood will be drawn from these animals, and these samples will be sent to a lab in the United States for zoonotic pathogen detection. The researchers will then assess the risk-taking behavior of the animals and also will evaluate their diets to determine the most likely explanation for these rodents' cohabitation with humans. By defining the patterns of infection and exposure among free-living rodents and humans, results of this research will suggest whether wild or commensal rodents present a bigger disease risk to humans, and by understanding the factors that influence commensalism, public health agencies can focus control efforts on the most likely areas of human-rodent overlap. In today's highly connected world, the health concerns arising from new disease outbreaks are truly global. Thus, by contributing to awareness and control of zoonotic outbreaks abroad, this study also will contribute to American health security.