Pusterla N, Johnson E M, Chae J S, Madigan J E
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, California 95616, USA.
J Helminthol. 2003 Dec;77(4):335-9. doi: 10.1079/joh2003181.
Neorickettsia (formerly Ehrlichia) risticii, the agent of Potomac horse fever (PHF), has been recently detected in trematode stages found in the secretions of freshwater snails and in aquatic insects. Insectivores, such as bats and birds, may serve as the definitive host of the trematode vector. To determine the definitive helminth vector, five bats (Myotis yumanensis) and three swallows (Hirundo rustica, Tachycineta bicolor) were collected from a PHF endemic location in northern California. Bats and swallows were dissected and their major organs examined for trematodes and for N. risticii DNA using a nested polymerase chain reaction (PCR) assay. Adult digenetic trematodes, Acanthatrium sp. and/or Lecithodendrium sp., were recovered from the gastrointestinal tract of all bats and from one swallow. The intestine of three bats, the spleen of two bats and one swallow as well as the liver of one swallow tested PCR positive for N. risticii. From a total of seven pools of identical digenetic trematodes collected from single hosts, two pools of Acanthatrium sp. and one pool of Lecithodendrium sp. tested PCR positive. The results of this investigation provide preliminary evidence that at least two trematodes in the family Lecithodendriidae are vectors of N. risticii. The data also suggest that bats and swallows not only act as a host for trematodes but also as a possible natural reservoir for N. risticii.
波托马克马热（PHF）的病原体里氏新立克次体（以前称为埃立克体 risticii）最近在淡水蜗牛分泌物和水生昆虫中发现的吸虫阶段被检测到。食虫动物，如蝙蝠和鸟类，可能是吸虫媒介的终末宿主。为了确定最终的蠕虫媒介，从加利福尼亚北部一个波托马克马热流行地区收集了五只蝙蝠（尤马鼠耳蝠）和三只燕子（家燕、双色树燕）。解剖蝙蝠和燕子，并使用巢式聚合酶链反应（PCR）检测法检查它们的主要器官是否有吸虫和里氏新立克次体DNA。从所有蝙蝠的胃肠道和一只燕子中发现了成年复殖吸虫棘盘属吸虫和/或枝睾属吸虫。三只蝙蝠的肠道、两只蝙蝠和一只燕子的脾脏以及一只燕子的肝脏经PCR检测里氏新立克次体呈阳性。从单个宿主收集的总共七组相同的复殖吸虫中，两组棘盘属吸虫和一组枝睾属吸虫经PCR检测呈阳性。这项调查的结果提供了初步证据，表明枝睾科中至少有两种吸虫是里氏新立克次体的媒介。数据还表明，蝙蝠和燕子不仅是吸虫的宿主，也是里氏新立克次体可能的天然宿主。
