A systems biology approach to infectious disease transmission: linking individuals populations and ecosystems

你有没有想过（并希望）蚊子会咬你的狗而不是你？生态学理论告诉我们，动物应该进化到专门的饮食，最能提高他们的生存和繁殖。在吸血昆虫的例子中，这种进化可以解释为什么有些物种只咬人类，而其他物种更喜欢驯养或野生动物。证据表明，大多数吸血昆虫的生存和繁殖，包括蚊子，臭虫，跳蚤和叮咬苍蝇，取决于它们叮咬的脊椎动物的种类。寄生虫在这些昆虫体内的生存也受到脊椎动物物种选择的影响，其中许多昆虫会导致人类和动物的严重疾病;一些动物的血液促进了寄生虫的生长，而另一些则阻止了寄生虫的生长。鉴于这种情况，如果吸血昆虫可利用的动物宿主范围在景观尺度上突然改变，这一变化将如何影响人类和动物疾病的传播？这个实验是在自然界中进行的，随着人类人口的增加，吸血昆虫可利用的动物种类正在迅速变化;减少了其他脊椎动物的可用性，有利于它们自己和它们的牲畜。脊椎动物物种选择范围的缩小对下游的影响尚不清楚;特别是它将如何影响生物多样性和叮咬昆虫的数量，以及它们携带的疾病的传播。了解脊椎动物宿主物种组成的这些变化如何影响叮咬昆虫的生存、种群增长和寄生虫传播潜力是本项目的中心目标。利用这些信息来制定和测试数学模型，预测昆虫丰度和疾病风险将如何变化，以应对特定的人类引起的土地利用变化，这是我的最终目标。在非洲这个遭受世界上最致命的虫媒疾病的大陆，土地使用做法的变化正在开始发生。大规模的城市化和密集的农业发展还不普遍，但在今后十年内将越来越普遍。因此，在这里比任何地方，研究脊椎动物物种多样性对吸血昆虫的影响，有可能提供先发制人的解决方案，与土地利用的变化相关的有害生态和流行病学的后果。我将进行一系列新的实验室分析，生物现实的行为测定，并密集的实地收集，以测试是否生存和繁殖的常见非洲蚊子冈比亚按蚊s.s.和一个. arabiensis受到它们喜欢的宿主物种（人和牛）相对于次要宿主物种（山羊、鸡和狗）的影响。我将测试这两种蚊子相互竞争的能力是否取决于它们首选宿主物种的相对丰度（人类对安。冈比亚，和牛为安。arabiensis）。最后，我将调查这些蚊子体内疟原虫的发展是否受到它们感染时所消耗的血液类型（人，牛，山羊，鸡或狗）的影响。在实验中收集的信息将用于制定蚊子和寄生虫种群增长的数学模型作为宿主物种组成的函数。我将使用这个模型来研究脊椎动物宿主的组成向人类倾斜（如城市化下所预期的那样），或者向牲畜和人类的混合物倾斜（如农业扩张下所预期的那样）将如何影响蚊子的丰度，生物多样性和疟疾传播强度。最后，这些模型将适合实际的景观在东非疟疾流行地区，以预测当前和预测的土地利用活动的变化可能会影响按蚊种群动态和人类健康。

Did you ever wonder (and wish) that mosquitoes would bite your dog instead of you? Ecological theory tells us that animals should evolve to specialize on diets that most increase their survival and reproduction. In the case of blood-feeding insects, this evolution may explain why some species bite only humans, whereas others prefer domesticated or wild animals. Evidence shows that the survival and reproduction of most blood-feeding insects, including mosquitoes, bed bugs, fleas, and biting flies, depends on the species of vertebrate that they bite. The survival of parasites within these insects, many of whom cause severe disease in humans and animals, is also influenced by vertebrate species choice; with the blood of some animals enhancing parasite growth, and others blocking it. Given this is the case, what would happen if the range of animal hosts available to blood-feeding insects was suddenly changed on a landscape scale, and how would this change impact the spread of human and animal disease? This experiment is occurring in nature, where the variety of animal species available to blood-feeding insects is rapidly changing as human populations expand; reducing the availability of other vertebrates in favour of themselves and their livestock. The downstream impacts of this narrowing of vertebrate species choice are not yet known; particularly with respect to how it will impact the biodiversity and abundance of biting insects, and the spread of the diseases they carry. Understanding how these changes in vertebrate host species composition influence the survival, population growth and parasite transmission potential of biting insects is the central aim of this project. Using this information to formulate and test mathematical models that predict how insect abundance and disease risk will change in response to specific human-induced land-use changes is my ultimate goal. In Africa, a continent inflicted by the world's deadliest insect-borne diseases; changes in land-use practices are starting to take place. Large-scale urbanization and intensive agricultural development are not yet common, but will become increasingly so within the next decade. Thus here more than anywhere, study of the impact of vertebrate species diversity on blood-feeding insects has the potential to provide pre-emptive solutions to detrimental ecological and epidemiological consequences associated with changes in land use. I will conduct a series of novel laboratory analyses, biologically realistic behavioural assays, and intensive field collections in order to test whether the survival and reproduction of the common African mosquitoes Anopheles gambiae s.s. and An. arabiensis is influenced by the availability of host species that they prefer (humans and cows) relative to those that are secondary (goats, chickens and dogs). I will test whether the ability of these two mosquito species to compete with one another is determined by the relative abundance of their preferred host species (humans for An. gambiae, and cows for An. arabiensis). Finally I will investigate whether the development of malaria parasites within these mosquitoes is influenced by the type of blood (human, cow, goat, chicken or dog) that they consume when they are infected. Information gathered in the experiments will be used to formulate a mathematical model of mosquito and parasite population growth as a function of host species composition. I will use this model to examine how skewing the composition of vertebrate hosts towards humans (as expected under urbanization), or to a mixture of livestock and humans (as expected under agricultural expansion) will influence mosquito abundance, biodiversity, and malaria transmission intensity. Finally, these models will be fit to actual landscapes within a malaria-endemic region of east Africa to predict how current and forecasted changes in land-use activities could impact Anopheline population dynamics and human health.