Role of fleas in transmission of rickettsiae: ecology of flea-borne spotted fever

描述（由申请人提供）：节肢动物作为几种新出现和重新出现的传染病病原体（包括猫立克次体）的载体。自首次在猫蚤中被描述以来，R.猫也成为人类的病原体。要了解这种病原体的潜在风险，我们必须首先了解生物体的生物学。我们的长期目标是阐明蚤媒介在维持和传播R。自然界中的猫确定跳蚤种群内的传播机制对于我们理解蚤传斑点热的流行病学至关重要，并广泛影响我们的控制措施。这些研究将评估无脊椎动物和脊椎动物宿主在R. felis的研究目的：（1）阐明了R.猫蚤通过猫蚤、猫栉首蚤和整个蚤群传播。参数R.猫感染和跳蚤传播;具体而言，a）水平传播（脊椎动物宿主的贡献和同时进食）; B）垂直传播（通过成体组织和生命周期的未成熟阶段复制和传播的动力学）; c）跳蚤适合度（繁殖力和羽化率）;和d）性别比畸变（雄性：雌性比的比较分析）将在受控实验室R中测量。猫C.猫模型;（2）通过评估脊椎动物宿主血粉和跳蚤种类对媒介能力的影响来研究蚤媒立克次体病的生态学。拟开展的研究将评估猫蚤对R.猫在替代血粉来源的存在下，以及能力的跳蚤物种以外的猫蚤获得和传播R。猫立克次体病是由立克次体的斑疹伤寒群和斑点热群成员引起的疾病。致病性立克次体通常通过节肢动物（昆虫和蜱）传播给人类。本项目旨在研究猫立克次体与媒介跳蚤之间的相互作用，以更好地了解蚤传斑疹热的生态学。

DESCRIPTION (provided by applicant): Arthropods serve as vectors for several emerging and reemerging infectious disease causing agents including Rickettsia felis. Since first being described in colonized cat fleas, R. felis has also emerged as a human pathogen. To understand the potential risk of this pathogen, we must first understand the biology of the organism. Our long-term objective is to delineate the role of the flea vector in the maintenance and transmission of R. felis in nature. Defining the mechanisms of transmission within populations of fleas is critical for our understanding of the epidemiology of flea-borne spotted fever and widely impacts our approach to control measures. The proposed studies will assess the role of invertebrate and vertebrate hosts in transmission of R. felis via the specific aims: (1) delineate the mechanisms by which R. felis spreads through individual cat fleas, Ctenocephalides felis, and throughout flea populations. Parameters of R. felis infection and transmission in fleas; specifically, a) horizontal transmission (contribution of vertebrate hosts and concurrent feeding); b) vertical transmission (dynamics of replication and dissemination through adult tissues and immature stages of life cycle); c) flea fitness (fecundity and eclosion rates); and d) sex ratio distortion (comparative analysis of male:female ratios) will be measured in a controlled laboratory R. felis/C. felis model; and (2) examine the ecology of flea-borne rickettsioses by assessing the influence of the vertebrate host bloodmeal and flea species on vector competence. Studies proposed will assess the vector competence of cat fleas for R. felis in the presence of alternate bloodmeal sources, as well as the competence of flea species other than cat fleas to acquire and transmit R. felis. Rickettsioses are diseases caused by members of the typhus group and spotted fever group of Rickettsia. Pathogenic Rickettsia are typically transmitted to humans by arthropods (insects and ticks). This project seeks to examine the interplay between Rickettsia felis and the vector flea, to better understand the ecology of flea-borne spotted fever.