Cardona Carol J, Ihejirika Arthur, McClellan Linda
Department of Population Health and Reproduction, University of California-Davis, 95616, USA.
Avian Dis. 2002 Jan-Mar;46(1):249-55. doi: 10.1637/0005-2086(2002)046[0249:HLIIBQ]2.0.CO;2.
This report chronicles recurring outbreaks of Haemoproteus lophortyx infection in captive bobwhite quail. Clinically, the signs of infection included reluctance to move, ruffled appearance, prostration, and death. These signs were associated with parasitemia, anemia, and the presence of large megaloschizonts in skeletal muscles, particularly those of the thighs and back. The average cumulative mortality for flocks experiencing outbreaks was over 20%. In a typical outbreak, mortality rose when the birds were 5-6 wk of age, peaked in 8-to-10-wk-old quail, and declined rapidly when the quail were 9-11 wk old. Outbreaks occurred exclusively between the months of May and October, and warm weather was determined to be a risk factor for H. lophortyx mortality. This protozoan most likely overwinters in native California quail in the area and is transmitted to quail on the ranch by an insect vector that emerges in warm weather. Infection of the large population of naïve bobwhite quail on the ranch leads to amplification of H. lophortyx, resulting in epidemics in successive flocks.
本报告记录了圈养的北美鹑中血变原虫感染的反复爆发情况。临床上，感染症状包括不愿活动、羽毛蓬乱、虚脱和死亡。这些症状与寄生虫血症、贫血以及骨骼肌中尤其是大腿和背部肌肉中出现的大型巨型裂殖体有关。经历疫情爆发的鸡群平均累计死亡率超过20%。在典型的疫情爆发中，死亡率在鸟类5至6周龄时上升，在8至10周龄的鹌鹑中达到峰值，而在鹌鹑9至11周龄时迅速下降。疫情仅在5月至10月期间发生，温暖天气被确定为血变原虫导致死亡的一个风险因素。这种原生动物很可能在该地区的加利福尼亚本土鹌鹑中越冬，并通过在温暖天气出现的昆虫媒介传播到牧场的鹌鹑身上。牧场中大量未接触过病原体的北美鹑感染后导致血变原虫数量增加，从而在连续的鸡群中引发疫情。
