Vector-Borne Disease Section, Communicable and Environmental Diseases, Tennessee Department of Health, 630 Hart Lane, Nashville, TN 37216, USA.
J Med Entomol. 2012 May;49(3):731-8. doi: 10.1603/me11151.
Human and equine outbreaks caused by eastern equine encephalomyelitis virus (EEEV) typically occur in North America adjacent to coastal wetlands associated with the presence of Culiseta melanura (Coquillet) mosquitoes. Eastern equine encephalomyelitis (EEE) is an emerging disease in Tennessee, as the first records of equine disease began in 2002. In 2006 we trapped and tested mosquitoes for EEEV at hardwood swamps in western Tennessee that were at the epicenter of a multi-equine outbreak in fall of 2005. Additionally, the Tennessee Valley Authority tested mosquito pools collected in Tennessee swamps from 2000 to 2007 for the presence of arboviruses. Two pools of EEEV positive Culex erraticus (Dyer and Knab) mosquitoes were found (one each in 2003 and 2004) in a county adjacent to where the 2005 outbreak occurred. In 2008, another EEE outbreak involving multiple horses occurred in West Tennessee. A brain specimen was collected from a horse during this outbreak and the first isolate of EEEV from Tennessee was obtained. In total, 74,531 mosquitoes collected from 2000 to 2008 were tested via polymerase chain reaction and VecTest for EEEV. The traditional enzootic vector, Cs. melanura, was found in low numbers at all collection sites. Cx. erraticus, however, was consistently found in high numbers and was the only mosquito species in which EEEV was detected. We suggest that EEE transmission may be maintained by Cx. erraticus in a nontraditional cycle. We discuss the importance of a nontraditional cycle from the perspective of EEEV adaptation and emergence.
人类和马属动物东部马脑炎病毒（EEEV）暴发通常发生在毗邻沿海湿地的北美洲，这些湿地与库蚊属（Culiseta）的库蚊（Coquillet）有关。田纳西州的东部马脑炎（EEE）是一种新出现的疾病，因为马病的首例记录始于 2002 年。2006 年，我们在田纳西州西部的硬木沼泽地捕捉并测试了蚊子，这些沼泽地是 2005 年秋季多匹马病暴发的中心。此外，田纳西河谷管理局测试了 2000 年至 2007 年从田纳西沼泽地采集的蚊子池，以确定是否存在虫媒病毒。在紧邻 2005 年暴发地区的一个县，发现了两批 EEEV 阳性的库蚊（Dyer and Knab）蚊子（分别在 2003 年和 2004 年各发现一批）。2008 年，田纳西州西部又发生了另一起涉及多匹马的 EEE 暴发。在此暴发期间，从一匹马身上采集了一个脑标本，获得了田纳西州的第一个 EEEV 分离株。总共从 2000 年至 2008 年收集了 74531 只蚊子，通过聚合酶链反应和 VecTest 测试了它们是否携带 EEEV。在所有采集地点，传统的地方性媒介库蚊（Cs. melanura）的数量都很低。然而，库蚊（Cx. erraticus）的数量一直很高，并且是唯一检测到 EEEV 的蚊子种类。我们认为，库蚊（Cx. erraticus）可能在非传统循环中维持 EEE 的传播。我们从 EEEV 适应和出现的角度讨论了非传统循环的重要性。
