Himsworth Chelsea G, Gurney Kirsty E B, Neimanis Aleksjia S, Wobeser Gary A, Leighton Fredrick A
Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.
Avian Dis. 2009 Mar;53(1):129-34. doi: 10.1637/8387-063008-Case.1.
This report describes West Nile virus (WNV)-associated mortality in captive lesser scaup (Aythya affinis) ducklings that occurred in Saskatchewan, Canada, in July and August 2007. There were no clinical signs or gross necropsy findings suggestive of the cause of death; however, microscopic lesions were consistent with WNV infection, including nonsuppurative encephalitis and myocardial, pancreatic, and splenic necrosis. Necrosis of the thymus and thyroid was also observed in some birds, which has not previously been reported in association with WNV infection. Immunohistochemistry revealed WNV antigen in multiple tissues, including thymus and thyroid, and reverse transcription polymerase chain reaction resulted in the identification of WNV gene sequence in all of the ducklings that were tested. This outbreak is of interest because waterfowl (Anseriformes) are not thought to be particularly susceptible to WNV, and there is little information about WNV infection in prefledging birds. The apparent susceptibility of lesser scaup to WNV demonstrated in this study may have implications for declining lesser scaup populations in the wild.
本报告描述了2007年7月和8月在加拿大萨斯喀彻温省发生的圈养小潜鸭（Aythya affinis）雏鸭中与西尼罗河病毒（WNV）相关的死亡情况。没有临床症状或大体尸检结果提示死亡原因；然而，微观病变与WNV感染一致，包括非化脓性脑炎以及心肌、胰腺和脾脏坏死。在一些鸟类中还观察到胸腺和甲状腺坏死，此前尚未有与WNV感染相关的报道。免疫组织化学显示在多个组织中存在WNV抗原，包括胸腺和甲状腺，逆转录聚合酶链反应在所有检测的雏鸭中都鉴定出了WNV基因序列。此次疫情令人关注，因为水禽（雁形目）通常被认为对WNV不太易感，而且关于出飞前鸟类感染WNV的信息很少。本研究中显示小潜鸭对WNV具有明显易感性，这可能对野生小潜鸭种群数量下降有影响。
