O'Brien Valerie A, Brown Charles R
Department of Biological Sciences, University of Tulsa, Tulsa, Oklahoma 74104, USA.
J Wildl Dis. 2012 Jan;48(1):138-47. doi: 10.7589/0090-3558-48.1.138.
Wild birds are rarely found with active arbovirus infections, and relatively little is known about the patterns of viremia they exhibit under field conditions or how infection varies with date, bird age, or other factors that potentially affect transmission dynamics. Buggy Creek virus (BCRV; Togaviridae, Alphavirus) is an arbovirus associated with colonially nesting Cliff Swallows (Petrochelidon pyrrhonota) and transmitted by its vector, the hematophagous swallow bug (Oeciacus vicarius), an ectoparasite of the Cliff Swallow. Introduced House Sparrows (Passer domesticus) that have occupied swallow nests at colony sites in peridomestic settings are also exposed to BCRV when fed upon by swallow bugs. We used data from 882 nestling House Sparrows in western Nebraska from 2006 to 2008 to examine seasonal variation and age-related correlates of virus infection in the field. Over 17% of nestling House Sparrows had active infections. Prevalence was higher in 2007 than in 2008 when birds from all colony sites were analyzed, but there was no significant difference between years for sites sampled in both seasons. Buggy Creek virus prevalence was similar in early and late summer, with a peak in midsummer, coinciding with the greatest swallow bug abundance. Nestlings 10 days of age and younger were most commonly infected, and the likelihood of BCRV infection declined for older nestlings. Average viremia titers also declined with age (but did not vary with date) and were high enough at all nestling ages to likely infect blood-feeding arthropods (swallow bugs). Length of viremia for nestlings in the field was ≥4 days, in agreement with an earlier study of BCRV. Nestling birds offer many advantages for field studies of arbovirus amplification and transmission.
野生鸟类很少被发现感染活跃的虫媒病毒，对于它们在野外条件下表现出的病毒血症模式，以及感染如何随日期、鸟类年龄或其他可能影响传播动态的因素而变化，人们了解得相对较少。巴吉溪病毒（BCRV；披膜病毒科，甲病毒属）是一种虫媒病毒，与群居筑巢的崖沙燕（Petrochelidon pyrrhonota）有关，并由其传播媒介——吸血的燕虱（Oeciacus vicarius）传播，燕虱是崖沙燕的一种体外寄生虫。在城郊环境中占据燕巢聚居地的引入物种家麻雀（Passer domesticus），当被燕虱叮咬时也会接触到BCRV。我们利用2006年至2008年来自内布拉斯加州西部882只家麻雀雏鸟的数据，研究了该病毒在野外的季节性变化以及与年龄相关的感染关联。超过17%的家麻雀雏鸟有活跃感染。当分析来自所有聚居地的鸟类时，2007年的患病率高于2008年，但在两个季节都采样的地点，年份之间没有显著差异。巴吉溪病毒的患病率在夏初和夏末相似，在仲夏达到峰值，这与燕虱数量最多的时期一致。10日龄及以下的雏鸟最常被感染，随着雏鸟年龄增长，感染BCRV的可能性下降。平均病毒血症滴度也随年龄下降（但不随日期变化），并且在所有雏鸟年龄都足够高，可能会感染吸血节肢动物（燕虱）。野外雏鸟的病毒血症持续时间≥4天，这与之前对BCRV的研究一致。雏鸟为虫媒病毒扩增和传播的野外研究提供了许多优势。
