Crans W J, Caccamise D F, McNelly J R
Department of Entomology, Rutgers, State University of New Jersey, New Brunswick 08903.
J Med Entomol. 1994 Sep;31(5):711-28. doi: 10.1093/jmedent/31.5.711.
Eastern equine encephalomyelitis virus (EEEV) is perpetuated in eastern North America in a mosquito-wild bird maintenance cycle that involves Culiseta melanura (Coquillett) as the principal enzootic vector and passerine birds as the primary amplifying hosts. We examined the role of birds in the EEEV cycle at a site in southern New Jersey where EEEV cycles annually at high levels. Birds and mosquitoes were sampled during three epiornitics and one season of limited virus activity. We examined antibody prevalence in birds in relation to eight physical and natural history characteristics. Our goal was to compare EEEV cycling in C. melanura and the primary avian hosts better to understand the mechanisms that initiate annual epiornitics. Antibody prevalence was highest in the Blue Jay (62%), Wood Thrush (60%), and Tufted Titmouse (44%). Resident status of birds was the natural history characteristic most closely linked to participation in the EEEV cycle. Species spending the greatest amount of time at our study site (permanent residents, summer residents) had the highest antibody rates. We captured viremic birds as early as 25 May, 51 d before we first detected virus in C. melanura. We recaptured 10 after hatching year adults and one hatching year (HY) bird that seroconverted before we detected virus in C. melanura. We also found EEEV antibody in 15 HY birds up to 31 d before we isolated EEEV from C. melanura. We provide evidence that a cryptic cycle develops weeks before epiornitic cycling is detected in C. melanura by traditional laboratory techniques, indicating that the early season cycle is initiated by the recrudescence of latent virus in previously infected birds.
东部马脑炎病毒（EEEV）在北美洲东部通过蚊子 - 野生鸟类传播循环得以持续存在，该循环涉及黑尾库蚊（Culiseta melanura，Coquillett）作为主要的动物流行病传播媒介以及雀形目鸟类作为主要的扩增宿主。我们在新泽西州南部的一个地点研究了鸟类在EEEV循环中的作用，该地点每年EEEV都有高水平的循环。在三次鸟类流行病和一个病毒活动有限的季节对鸟类和蚊子进行了采样。我们研究了与八个身体和自然史特征相关的鸟类抗体流行率。我们的目标是更好地比较黑尾库蚊和主要鸟类宿主中的EEEV循环，以了解引发年度鸟类流行病的机制。抗体流行率在冠蓝鸦（62%）、伍德鸫（60%）和簇山雀（44%）中最高。鸟类的居留状态是与参与EEEV循环最密切相关的自然史特征。在我们研究地点停留时间最长的物种（永久居民、夏季居民）抗体率最高。我们最早在5月25日捕获到病毒血症鸟类，比我们首次在黑尾库蚊中检测到病毒早51天。我们在孵化年后的成年鸟中有10只被重新捕获，还有1只孵化年（HY）鸟类在我们在黑尾库蚊中检测到病毒之前血清转化。在我们从黑尾库蚊中分离出EEEV之前，我们还在15只HY鸟类中发现了EEEV抗体，时间长达31天。我们提供的证据表明，在通过传统实验室技术在黑尾库蚊中检测到鸟类流行病循环之前数周，就已经形成了一个隐匿循环，这表明早期季节循环是由先前感染鸟类中潜伏病毒的复发引发 的。
