Transmission of Rickettsia africae by Amblyomma americanum and Amblyomma maculatum

项目概要/摘要 由非洲立克次体引起的非洲蜱叮咬热可能是人类最常见的斑点 热群立克次体病它发生在整个非洲，无论其主要媒介， 其他Amblyomma属的物种也能传播R.非洲和生物体 已经在印度洋和太平洋的候鸟身上传播了一种名为Amblyomma loculosum的病毒 群岛非洲立克次体也发生在中美洲的A.在加勒比海， 岛屿A。在19世纪从非洲进口的牛身上发现的。感染的虱子 广泛分布在加勒比群岛的牛背鹭上，牛背鹭是一种候鸟 在岛屿之间移动很容易，远至佛罗里达群岛。 R.在附近的加勒比群岛和中美洲，非洲， 扩大这些地区与美国之间的旅游业和贸易， 来自非洲、加勒比海和中美洲的感染了R.非洲和 候鸟的存在增加了A. variegatum和/或R.非洲正在引进 进入美国并建立。如果美国特有的Amblyomma物种可以 感染并维持和传播R.非洲蜱叮咬热可能成为 在美国建立，造成广泛的发病率，因为它在非洲。而且这个 将使已经很难诊断的美国斑点热群进一步复杂化， 立克次体感染，特别是落基山斑疹热。R.非洲论 美国的野生动物是未知的。 为了建立最相关的美国Amblyomma物种的水库和媒介容量，A。 americanum和A. maculatum我们打算用几内亚进行传播实验 猪和小牛作为宿主。多花钝眼蜱（Amblyomma variegatum）幼虫/成虫感染R. africae将分别用豚鼠或小牛喂养， 未成熟和成年美国Amblyomma物种，以确定感染是否可以转移 水平。如果感染可以在美国Amblyomma物种中得到证实， 将进行实验以确定R. Africae可以垂直传播 喂养阶段（transstadially），transovarially通过鸡蛋，并从每个喂养阶段， 主持人 这些实验产生的数据将使美国卫生工作者能够更精确地 确定非洲蜱叮咬热在美国建立的风险，并为适当的 制定预防和应对战略。

Project Summary/ Abstract African tick-bite fever caused by Rickettsia africae is probably the most common human spotted fever group rickettsiosis. It occurs throughout Africa, wherever its major vector, Amblyomma variegatum, is found. Other Amblyomma species can also transmit R. africae and the organism has spread in Amblyomma loculosum on migratory birds through the Indian and Pacific Ocean islands. Rickettsia africae also occurs in Central America in A. ovale, and in the Caribbean islands in A. variegatum which were imported on cattle from Africa in the 1800s. Infected ticks were spread widely around the Caribbean islands on cattle egrets, which are migratory birds that move readily between the islands and as far as the Florida Keys. The presence of R. africae in the nearby Caribbean islands and Central America, and Africa, the expanding tourism and trade between these areas and the USA, the travelers entering the USA from Africa, the Caribbean, and Central America that are infected with R. africae, and the presence of migratory birds raises the risks of A. variegatum and/or R. africae being introduced into the USA and becoming established. If Amblyomma species endemic in the USA could then become infected with and maintain and transmit R. africae, African tick-bite fever could become established in the USA causing widespread morbidity as it does in Africa. Additionally, this would further complicate the already difficult diagnosis of American spotted fever group Rickettsia infections, in particular Rocky Mountain spotted fever. The effects of R. africae on American wildlife are unknown. To establish the reservoir and vector capacity of the most relevant US Amblyomma species, A. americanum and A. maculatum, we intend to conduct transmission experiments with guinea pigs and calves as hosts. Amblyomma variegatum larvae/ nymphs and adults infected with R. africae will be fed on guinea pigs or calves, respectively, at the same time as uninfected immature and adult US Amblyomma species to determine if infections can be transferred horizontally. If infections can be demonstrated in the US Amblyomma species, further experiments will be performed to establish if R. africae can be transmitted vertically between feeding stages (transtadially), transovarially through the eggs, and from each feeding stage to the host. Data generated from these experiments will enable American health workers to more precisely determine the risk of African tick-bite fever becoming established in the USA and for appropriate prevention and response strategies to be developed.