Peter T F, Burridge M J, Mahan S M
University of Florida/USAID/SADC Heartwater Research Project, Causeway, Harare, Zimbabwe.
J Parasitol. 2000 Jun;86(3):438-41. doi: 10.1645/0022-3395(2000)086[0438:COTATT]2.0.CO;2.
The ability of the African tortoise tick, Amblyomma marmoreum, to acquire and transmit Cowdria ruminantium infection was investigated experimentally with transmission trials and with a C. ruminantium-specific polymerase chain reaction (PCR) detection assay. Laboratory-reared A. marmoreum larvae and nymphs were fed on small ruminants with clinical heartwater. After molting, the resultant nymphs were fed on Cowdria ruminantium-naive sheep (n = 3), and the adults were ground and inoculated intravenously into sheep (n = 5). Fatal heartwater developed in the 5 recipient animals, demonstrating larvae-nymph transmission and nymph-adult acquisition of infection. Cowdria ruminantium infection was also detected in adult A. marmoreum by PCR analysis, although at lower frequency (10%) than in Amblyomma hebraeum ticks (43%), the major vector of C. ruminantium in southern Africa, which had been fed simultaneously on the infected animals (P<0.0001). Amblyomma marmoreum, therefore, can be an effective vector of C. ruminantium. The potential role of this species in heartwater epidemiology and in the spread of the disease to new areas is highlighted by these results and by the fact that immature stages of this tick feed readily on domestic and wild animals susceptible to C. ruminantium.
通过传播试验以及使用反刍兽考德里氏体特异性聚合酶链反应（PCR）检测方法，对非洲陆龟蜱（Amblyomma marmoreum）获取和传播反刍兽考德里氏体感染的能力进行了实验研究。在实验室饲养的非洲陆龟蜱幼虫和若虫以患有临床心水病的小反刍动物为食。蜕皮后，将所得若虫以未感染反刍兽考德里氏体的绵羊（n = 3）为食，然后将成虫研磨并静脉接种到绵羊（n = 5）体内。5只受体动物均出现致命的心水病，证明了幼虫到若虫的传播以及若虫到成虫的感染获取。通过PCR分析在成年非洲陆龟蜱中也检测到了反刍兽考德里氏体感染，尽管其频率（10%）低于同时以感染动物为食的南非反刍兽考德里氏体主要传播媒介希伯来花蜱（Amblyomma hebraeum）（43%）（P<0.0001）。因此，非洲陆龟蜱可以成为反刍兽考德里氏体的有效传播媒介。这些结果以及该蜱的未成熟阶段易于以易感染反刍兽考德里氏体的家养和野生动物为食这一事实，突出了该物种在心水病流行病学以及疾病向新地区传播中的潜在作用。
