Davidson Rebecca K, Ličina Tina, Gorini Lucrezia, Milner Jos M
Norwegian Veterinary Institute, Pb 750 Sentrum, 0106 Oslo, Norway.
Faculty of Applied Ecology and Agricultural Sciences, Hedmark University College, Evenstad, 2480 Koppang, Norway.
Int J Parasitol Parasites Wildl. 2015 Jan 7;4(1):29-36. doi: 10.1016/j.ijppaw.2014.12.005. eCollection 2015 Apr.
Many health surveillance programs for wild cervids do not include routine parasite screening despite evidence that gastrointestinal parasites can affect wildlife population dynamics by influencing host fecundity and survival. Slaughter weights of moose in some regions of Norway have been decreasing over recent decades but any role of parasites has not yet been considered. We investigated parasite faunal diversity of moose in Hedmark, SE Norway, by faecal analysis and identification of adult abomasal and caecal nematodes during the autumn hunting season. We related parasite prevalence and abundance to estimates of body condition, gender and age. We identified 11 parasite groups. Moose had high abomasal gastrointestinal nematode (GIN) burdens and all individuals were infected. Ostertagia antipini and Spiculopteragia alcis were the most prevalent abomasal GINs identified. O. leptospicularis and Telodorsagia circumcincta were also identified in the abomasa while a range of other GIN and Moniezia sp. eggs, and coccidia, Dictyocaulus sp. and Protostrongylid larvae were found in faeces. Female moose had higher mean abomasal nematode counts than males, particularly among adults. However, adult males had higher faecal egg counts than adult females which may reflect reduction in faecal volume with concentration of eggs among males during the rut. We found no strong evidence for the development of acquired immunity to abomasal nematodes with age, although there was a higher Protostrongylid and Moniezia infection prevalence in younger animals. High burdens of several parasites were associated with poor body condition in terms of slaughter weight relative to skeletal size but unrelated to visually evaluated fat reserves. Given findings from earlier experimental studies, our results imply sub-clinical effects of GI parasite infection on host condition. Managers should be aware that autumn faecal egg counts and field assessments of fat reserves may not be reliable indicators of parasitism and may underestimate impacts on wildlife populations.
尽管有证据表明胃肠道寄生虫可通过影响宿主繁殖力和存活率来影响野生动物种群动态，但许多针对野生鹿类的健康监测项目并未将常规寄生虫筛查纳入其中。挪威部分地区驼鹿的屠宰体重在近几十年一直在下降，但寄生虫在其中所起的任何作用尚未得到考量。我们在挪威东南部海德马克郡的秋季狩猎季节，通过粪便分析以及对成年皱胃和盲肠线虫的鉴定，调查了驼鹿的寄生虫区系多样性。我们将寄生虫的感染率和丰度与身体状况、性别和年龄的估计值关联起来。我们鉴定出了11个寄生虫类群。驼鹿的皱胃胃肠道线虫（GIN）负荷很高，所有个体均被感染。奥氏反刍类圆线虫和阿尔氏细颈线虫是鉴定出的最常见的皱胃GIN。在皱胃中还鉴定出了细颈奥斯特线虫和环形泰勒线虫，同时在粪便中发现了一系列其他GIN和莫尼茨绦虫属虫卵，以及球虫、网尾线虫属和原圆科幼虫。雌性驼鹿的皱胃线虫平均数量高于雄性，尤其是在成年个体中。然而，成年雄性的粪便虫卵数高于成年雌性，这可能反映出在发情期雄性粪便量减少而虫卵浓度增加。我们没有找到有力证据表明随着年龄增长对皱胃线虫会产生获得性免疫，尽管幼龄动物中原圆科和莫尼茨绦虫的感染率更高。相对于骨骼大小，就屠宰体重而言，几种寄生虫的高负荷与身体状况不佳有关，但与视觉评估的脂肪储备无关。根据早期实验研究的结果，我们的研究结果暗示了胃肠道寄生虫感染对宿主状况的亚临床影响。管理者应意识到秋季粪便虫卵数和野外脂肪储备评估可能不是寄生虫感染的可靠指标，可能会低估对野生动物种群的影响。
