Goldberg D R, Yuill T M, Burgess E C
Department of Veterinary Science, University of Wisconsin, Madison 53706.
J Wildl Dis. 1990 Jul;26(3):299-306. doi: 10.7589/0090-3558-26.3.299.
Environmental contaminants contain chemicals that, if ingested, could affect the immunological status of wild birds, and in particular, their resistance to infectious disease. Immunosuppression caused by environmental contaminants, could have a major impact on waterfowl populations, resulting in increased susceptibility to contagious disease agents. Duck plague virus has caused repeated outbreaks in waterfowl resulting in mortality. In this study, several doses of cyclophosphamide (CY), a known immunosuppressant, were administered to adult mallards (Anas platyrhynchos) to determine if a resultant decrease in resistance to a normally sub-lethal strain of duck plague virus would occur, and induce mortality in these birds. Death occurred in birds given CY only, and in birds given virus and CY, but not in those given virus only. There was significantly greater mortality and more rapid deaths in the duck plague virus-infected groups than in groups receiving only the immunosuppressant. A positively correlated dose-response effect was observed with CY mortalities, irrespective of virus exposure. A fuel oil and a crude oil, common environmental contaminants with immunosuppressive capabilities, were tested to determine if they could produce an effect similar to that of CY. Following 28 days of oral oil administration, the birds were challenged with a sub-lethal dose of duck plague virus. No alteration in resistance to the virus (as measured by mortality) was observed, except in the positive CY control group.
环境污染物含有一些化学物质，如果被野生鸟类摄入，可能会影响其免疫状态，尤其是它们对传染病的抵抗力。环境污染物导致的免疫抑制可能会对水禽种群产生重大影响，导致它们对传染性病原体的易感性增加。鸭瘟病毒已在水禽中多次引发疫情，导致死亡。在本研究中，给成年绿头鸭（Anas platyrhynchos）注射了几剂已知的免疫抑制剂环磷酰胺（CY），以确定是否会导致对通常亚致死剂量的鸭瘟病毒的抵抗力下降，并导致这些鸟类死亡。仅注射CY的鸟类以及同时注射病毒和CY的鸟类出现了死亡，但仅注射病毒的鸟类未出现死亡。与仅接受免疫抑制剂的组相比，感染鸭瘟病毒的组死亡率显著更高，死亡速度更快。无论是否接触病毒，CY导致的死亡率都呈现出正相关的剂量反应效应。对具有免疫抑制能力的常见环境污染物燃油和原油进行了测试，以确定它们是否能产生与CY类似的效果。在口服油类28天后，给鸟类注射亚致死剂量的鸭瘟病毒。除了阳性CY对照组外，未观察到对病毒的抵抗力（以死亡率衡量）有任何变化。
