Department of Vector Assessment, Virology Division, United States Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, MD 21702, USA.
J Med Entomol. 2010 Sep;47(5):884-9. doi: 10.1603/me10007.
To determine which arthropods should be targeted for control should Rift Valley fever virus (RVFV) be detected in North America, we evaluated Culex erraticus (Dyar and Knab), Culex erythrothorax Dyar, Culex nigripalpus Theobald, Culex pipiens L., Culex quinquefasciatus Say, Culex tarsalis Coquillett, Aedes dorsalis (Wiedemann), Aedes vexans (Meigen), Anopheles quadrimaculatus Say, and Culicoides sonorensis Wirth and Jones from the western, midwestern, and southern United States for their ability to transmit RVFV. Female mosquitoes were allowed to feed on adult hamsters inoculated with RVFV, after which engorged mosquitoes were incubated for 7-21 d at 260C, then allowed to refeed on susceptible hamsters, and tested to determine infection, dissemination, and transmission rates. Other specimens were inoculated intrathoracically, held for 7 d, and then allowed to feed on a susceptible hamster to check for a salivary gland barrier. When exposed to hamsters with viremias > or =10(8.8) plaque-forming units/ml blood, Cx. tarsalis transmitted RVFV efficiently (infection rate = 93%, dissemination rate = 56%, and estimated transmission rate = 52%). In contrast, when exposed to the same virus dose, none of the other species tested transmitted RVFV efficiently. Estimated transmission rates for Cx. erythrothorax, Cx. pipiens, Cx. erraticus, and Ae. dorsalis were 10, 8, 4, and 2%, respectively, and for the remaining species were < or = 1%. With the exception of Cx. tarsalis and Cx. pipiens, all species tested had moderate to major salivary gland barriers. None of the C. sonorensis became infected and none of the An. quadrimaculatus tested transmitted RVFV by bite, even after intrathoracic inoculation, indicating that these species would not be competent vectors of RVFV. Although Ae. vexans from Florida and Louisiana were relatively efficient vectors of RVFV, specimens of this species captured in Colorado or California were virtually incompetent, illustrating the need to evaluate local population for their ability to transmit a pathogen. In addition to laboratory vector competence, factors such as seasonal density, host feeding preference, longevity, and foraging behavior should be considered when determining the potential role that these species could play in RVFV transmission.
为了确定在北美发现裂谷热病毒（RVFV）时应该控制哪些节肢动物，我们评估了来自美国西部、中西部和南部的库蚊属（Culex）中的埃及伊蚊（Aedes）、致倦库蚊（Culex）、棕头库蚊（Culex）、白纹伊蚊（Culex）、淡色库蚊（Culex）、库蚊（Culex）、刺扰伊蚊（Aedes）、疟蚊（Anopheles）和斑须库蚊（Culicoides）传播 RVFV 的能力。雌性蚊子被允许吸食接种 RVFV 的成年仓鼠，然后将吸血后的蚊子在 26°C 下孵育 7-21 天，然后让它们重新吸食易感仓鼠，并进行感染、传播和感染率测试。其他标本通过胸内接种，放置 7 天，然后让它们吸食易感仓鼠以检查唾液腺屏障。当暴露于病毒血症≥10（8.8）噬菌斑形成单位/ml 血液的仓鼠时，Cx. tarsalis 有效地传播 RVFV（感染率=93%，传播率=56%，估计传播率=52%）。相比之下，当暴露于相同病毒剂量时，测试的其他物种均不能有效地传播 RVFV。Cx. erythrothorax、Cx. pipiens、Cx. erraticus 和 Ae. dorsalis 的估计传播率分别为 10%、8%、4%和 2%，其余物种的传播率均≤1%。除了 Cx. tarsalis 和 Cx. pipiens 之外，所有测试的物种均具有中度至重度唾液腺屏障。没有一只 C. sonorensis 感染，也没有一只测试的 An. quadrimaculatus 通过叮咬传播 RVFV，即使通过胸内接种也是如此，这表明这些物种不会成为 RVFV 的有效传播媒介。尽管来自佛罗里达州和路易斯安那州的 Ae. vexans 是 RVFV 的相对有效传播媒介，但在科罗拉多州或加利福尼亚州捕获的这种物种几乎没有传播能力，这表明需要评估当地种群传播病原体的能力。除了实验室媒介能力外，在确定这些物种在 RVFV 传播中可能发挥的潜在作用时，还应考虑季节性密度、宿主取食偏好、寿命和觅食行为等因素。
