Halvorsen O, Stien A, Irvine J, Langvatn R, Albon S
Zoological Museum, University of Oslo, Norway.
Int J Parasitol. 1999 Apr;29(4):567-79. doi: 10.1016/s0020-7519(99)00005-3.
Living in the high Arctic, the Svalbard reindeer (Rangifer tarandus platyrhynchus) and its trichostrongyle nematodes experience a long cold winter from October to late May/early June. Over this period, transmission would be expected to be low. However, in culled reindeer the abundance of infection increased from autumn to late winter, providing evidence for continued transmission within this period. To our knowledge this is the first time this has been demonstrated in a climate with temperatures consistently below 0 degrees C. In one winter (1996-1997), the average fraction of nematodes found as larvae in the abomasal mucosa increased from around 10% to 50% between October and March. This suggests that arrested development took place throughout the winter. We found no evidence for an efficient acquired immune response towards the nematodes. The abundance of infection did not tend to decrease with increasing host age after an earlier peak, but levelled off instead, as predicted by a simple immigration-death model. In the late winter when the nutritional plane is low, both adult reindeer and calves had high worm burdens at intensities that may affect their condition and fitness.
斯瓦尔巴德驯鹿（Rangifer tarandus platyrhynchus）生活在北极地区，其毛圆线虫会经历从10月到次年5月底/6月初漫长寒冷的冬季。在此期间，预计传播率较低。然而，在被扑杀的驯鹿中，感染丰度从秋季到冬末有所增加，这为该时期内的持续传播提供了证据。据我们所知，这是首次在持续低温（低于0摄氏度）的气候条件下证明这一现象。在一个冬季（1996 - 1997年），10月至3月期间，在皱胃黏膜中发现的幼虫形式的线虫平均比例从约10%增加到了50%。这表明整个冬季都发生了发育停滞。我们没有发现针对线虫的有效获得性免疫反应的证据。感染丰度在早期达到峰值后，并没有随着宿主年龄的增加而趋于下降，而是如简单的迁入 - 死亡模型所预测的那样趋于平稳。在冬末营养水平较低时，成年驯鹿和幼鹿都有很高的蠕虫负荷，这种强度可能会影响它们的身体状况和健康。
