Telfer S, Birtles R, Bennett M, Lambin X, Paterson S, Begon M
School of Biological Sciences, University of Liverpool, Biosciences Building, Liverpool L69 7LB, UK.
Parasitology. 2008 Jun;135(7):767-81. doi: 10.1017/S0031182008000395. Epub 2008 May 12.
The physiological and immunological state of an animal can be influenced by current infections and infection history. Consequently, both ongoing and previous infections can affect host susceptibility to another parasite, the biology of the subsequent infection (e.g. infection length) and the impact of infection on host morbidity (pathology). In natural populations, most animals will be infected by a succession of different parasites throughout the course of their lives, with probably frequent concomitant infections. The relative timing of different infections experienced by a host (i.e. the sequence of infection events), and the effects on factors such as host susceptibility and host survival, can only be derived from longitudinal data on individual hosts. Here we review some of the evidence for the impact of co-infection on host susceptibility, infection biology and pathology focusing on insights obtained from both longitudinal studies in humans and experiments that explicitly consider the sequence of infection. We then consider the challenges posed by longitudinal infection data collected from natural populations of animals. We illustrate their usefulness using our data of microparasite infections associated with field vole (Microtus agrestis) populations to examine impacts on susceptibility and infection length. Our primary aim is to describe an analytical approach that can be used on such data to identify interactions among the parasites. The preliminary analyses presented here indicate both synergistic and antagonistic interactions between microparasites within this community and emphasise that such interactions could have significant impacts on host-parasite fitness and dynamics.
动物的生理和免疫状态会受到当前感染及感染史的影响。因此，正在发生的感染和既往感染都会影响宿主对另一种寄生虫的易感性、后续感染的生物学特性（如感染时长）以及感染对宿主发病率（病理学）的影响。在自然种群中，大多数动物在其一生中会先后感染一系列不同的寄生虫，可能还经常伴有混合感染。宿主经历的不同感染的相对时间（即感染事件的顺序），以及对宿主易感性和宿主存活等因素的影响，只能从个体宿主的纵向数据中得出。在此，我们回顾一些关于混合感染对宿主易感性、感染生物学和病理学影响的证据，重点关注从人类纵向研究以及明确考虑感染顺序的实验中获得的见解。然后，我们考虑从动物自然种群收集的纵向感染数据所带来的挑战。我们利用与田鼠（Microtus agrestis）种群相关的微寄生虫感染数据来说明其有用性，以研究对易感性和感染时长的影响。我们的主要目的是描述一种可用于此类数据以识别寄生虫之间相互作用的分析方法。此处呈现的初步分析表明，该群落内微寄生虫之间存在协同和拮抗相互作用，并强调此类相互作用可能对宿主 - 寄生虫适应性和动态产生重大影响。
