Transmission of Rickettsia africae by Amblyomma americanum and Amblyomma maculatum

美洲钝眼虫和斑钝眼虫传播非洲立克次体

基本信息

批准号：
9894993
负责人：
Patrick Kelly
金额：
$ 5.3万
依托单位：
ROSS UNIVERSITY SCH/VETERINARY MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-03-10 至 2022-02-28
项目状态：
已结题

项目摘要

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.

项目概要/摘要由非洲立克次体引起的非洲蜱虫叮咬热可能是人类最常见的发现发热群立克次体病。它发生在整个非洲，无论其主要媒介是 Amblyomma 杂色，被发现。其他 Amblyomma 物种也可以传播 R. africae 和该生物体已通过印度洋和太平洋的候鸟身上的 Amblyomma loculosum 传播岛屿。非洲立克次体也出现在中美洲的 A. ovale 和加勒比地区 1800 年代从非洲通过牛进口的 A. variegatum 岛屿。受感染的蜱虫广泛分布在加勒比岛屿周围的牛背鹭上，牛背鹭是一种候鸟它们可以轻松地在岛屿之间移动，最远可以到达佛罗里达群岛。 R. africae 存在于附近的加勒比岛屿和中美洲以及非洲扩大这些地区与美国之间的旅游和贸易，进入美国的游客来自非洲、加勒比海地区和中美洲的感染了 R. african 的病毒，以及候鸟的存在增加了斑鸠菊和/或非洲鹤的引入风险进入美国并成立。如果美国特有的 Amblyomma 物种可以感染并维持和传播非洲蜱虫，非洲蜱虫叮咬热可能会发展为与非洲一样，它在美国建立，造成广泛的发病率。另外，这将使本已困难的美国斑疹热群诊断变得更加复杂立克次体感染，特别是落基山斑疹热。非洲R. africae的影响美洲野生动物尚不为人所知。为了确定最相关的美国 Amblyomma 物种的储存库和媒介容量，A. americanum 和 A. maculatum，我们打算在几内亚进行传播实验猪和牛犊作为宿主。感染 R. Amblyomma variegatum 幼虫/若虫和成虫。非洲猪将与未感染的猪同时分别喂食豚鼠或小牛未成熟和成年的美国 Amblyomma 物种以确定感染是否可以转移水平地。如果可以在美国 Amblyomma 物种中证实感染，进一步将进行实验以确定 R. africae 是否可以在之间垂直传播喂养阶段（经跨卵），经卵通过卵，以及从每个喂养阶段到主人。这些实验产生的数据将使美国卫生工作者能够更准确地确定非洲蜱虫叮咬热在美国流行的风险，并采取适当的措施有待制定预防和应对策略。