Collaborative Research: Microparasite-Macroparasite Interactions: Dynamics of Co-infection and Implications for Disease Control

摘要在大多数自然种群中，多种寄生虫感染宿主是正常的，而不是例外的，但对寄生虫动态的研究主要集中在单一寄生虫与单一宿主的相互作用上。免疫学的基本原理表明，微寄生虫(细菌、病毒、原生动物)和大型寄生虫(蠕虫)共同感染宿主应该对疾病动态产生重要影响。例如，接触大型寄生虫可能会增加宿主对艾滋病、结核病和疟疾等重要微寄生病的易感性和进展。这项研究的中心目标是在三个不同的生物组织水平上调查微寄生虫和大型寄生虫相互作用对疾病模式的影响：个体、种群和物种。为了实现这一目标，将以非洲水牛(Syncerus Caffer)感染牛结核病(BTB)和胃肠道线虫作为模型系统来研究个体水平的感染模式和寄生虫种群动态。具体地说，将使用野外和圈养研究以及数学建模相结合的方法来评估这些自由放养动物的感染和免疫模式，了解线虫治疗对BTB传播的影响，并研究BTB对线虫的相互影响。在这个系统的基础上，一个感染野生哺乳动物和人类的寄生虫和病原体的综合数据库将被用来调查蠕虫对微寄生虫病在种群和物种中分布的影响。结合起来，这些分析将揭示寄主内微型寄生虫和大型寄生虫之间的免疫相互作用如何影响自然寄主种群和物种之间的疾病模式。这项研究的更广泛影响包括培训多名研究生、本科生和辅助专业人员；将研究成果应用于一种具有生态和经济意义的野生动物疾病的管理；与公共卫生界积极合作，了解将蠕虫控制作为抗击人类微寄生虫病的工具的效用。

Abstract Infection of hosts by multiple parasite species is the norm rather than the exception in most natural populations, yet studies of parasite dynamics largely focus on single parasites interacting with single hosts. Fundamental principles of immunology suggest that co-infection of hosts by microparasites (bacteria, viruses, protozoa) and macroparasites (helminths) should have important effects on disease dynamics. For example, exposure to macroparasites may increase host susceptibility to and progression of important microparasitic diseases such as AIDS, tuberculosis and malaria in humans. The central goal of this study is to investigate the consequences of microparasite-macroparasite interactions for patterns of disease at three distinct levels of biological organization: individuals, populations and species. To achieve this goal, African buffalo (Syncerus caffer) co-infected with bovine tuberculosis (BTB, Mycobacterium bovis) and gastrointestinal nematodes will be used as a model system to investigate individual-level patterns of infection and parasite population dynamics. Specifically, a combination of field and captive studies and mathematical modeling will be used to assess patterns of infection and immunity in these free-ranging animals, understand the effects of nematode treatment on BTB transmission, and examine the reciprocal effects of BTB on nematodes. Scaling up from this system, a comprehensive database of parasites and pathogens infecting wild mammals and humans will then be used to investigate the effect of helminths on the distribution of microparasitic diseases across populations and species. In combination, these analyses will reveal how within-host immunological interactions between micoparasites and macroparasites shape patterns of disease in natural host populations and among species. Broader impacts of this study include training of multiple graduate students, undergraduate students and paraprofessionals; application of study results to the management of an ecologically and economically important wildlife disease; and active collaboration with the public health community to understand the utility of using helminth control as a tool for combating microparasitic diseases in humans.