Reisen William K, Barker Christopher M, Carney Ryan, Lothrop Hugh D, Wheeler Sarah S, Wilson Jennifer L, Madon Minoo B, Takahashi Richard, Carroll Brian, Garcia Sandra, Fang Ying, Shafii Marzieh, Kahl Nicole, Ashtari Siranoosh, Kramer Vicki, Glaser Carol, Jean Cynthia
Center for Vectorborne Diseases, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
J Med Entomol. 2006 Mar;43(2):356-67. doi: 10.1603/0022-2585(2006)043[0356:rocieo]2.0.co;2.
The invasion of different southern California landscapes by West Nile virus (WNV) and its subsequent amplification to epidemic levels during 2004 enabled us to study the impact of differing corvid populations in three biomes: the hot Colorado desert with few corvids (Coachella Valley), the southern San Joaquin Valley (Kern County) with large western scrub-jay but small American crow populations, and the cool maritime coast (Los Angeles) with a large clustered American crow population. Similar surveillance programs in all three areas monitored infection rates in mosquitoes, seroconversion rates in sentinel chickens, seroprevalence in wild birds, numbers of dead birds reported by the public, and the occurrence of human cases. Infection rates in Culex tarsalis Coquillett and sentinel chicken seroconversion rates were statistically similar among all three areas, indicating that highly competent mosquito hosts were capable of maintaining enzootic WNV transmission among less competent and widely distributed avian hosts, most likely house sparrows and house finches. In contrast, infection rates in Culex pipiens quinquefasciatus Say were statistically higher in Kern and Los Angeles counties with elevated corvid populations than in Coachella Valley with few corvids. Spatial analyses of dead corvids showed significant clusters near known American crow roosts in Los Angeles that were congruent with clusters of human cases. In this area, the incidence of human and Cx. p. quinquefasciatus infection was significantly greater within corvid clusters than without, indicating their importance in virus amplification and as a risk factor for human infection. In contrast the uniform dispersion by territorial western scrub-jays resulted in a high, but evenly distributed, incidence of human disease in Kern County.
西尼罗河病毒（WNV）对南加州不同景观的侵袭以及随后在2004年其传播至流行水平，使我们能够研究三种生物群落中不同鸦科种群的影响：鸦科种群稀少的炎热科罗拉多沙漠（科切拉谷）、西部灌丛鸦数量众多但美洲乌鸦数量较少的圣华金谷南部（克恩县），以及美洲乌鸦大量聚集的凉爽沿海地区（洛杉矶）。所有这三个地区类似的监测项目监测了蚊子的感染率、哨兵鸡的血清转化率、野生鸟类的血清阳性率、公众报告的死鸟数量以及人类病例的发生情况。在所有这三个地区，致倦库蚊的感染率和哨兵鸡的血清转化率在统计学上相似，这表明高传播能力的蚊子宿主能够在传播能力较弱且分布广泛的禽类宿主（很可能是家麻雀和家朱雀）之间维持WNV的地方性传播。相比之下，在克恩县和洛杉矶县，有较高鸦科种群数量的地区，致倦库蚊的感染率在统计学上高于鸦科种群稀少的科切拉谷。对死亡鸦科鸟类的空间分析显示，在洛杉矶已知的美洲乌鸦栖息地附近存在显著的聚集现象，这些聚集区域与人类病例的聚集区域一致。在该地区，鸦科鸟类聚集区域内人类和致倦库蚊感染的发生率显著高于非聚集区域，这表明它们在病毒增殖以及作为人类感染风险因素方面的重要性。相比之下，领地意识较强的西部灌丛鸦的均匀分布导致克恩县人类疾病的发生率较高，但分布均匀。
