The first case of chronic wasting disease diagnosed in Europe. Photo taken by Lars Nesse.

Imagine early spring in the Norwegian mountains. The scenery is pristine, with white snow and clear blue sky. This morning, however, the silence is broken by a helicopter maneuvering between the mountains like an annoying mosquito. In it, a team from the Norwegian Institute for Nature Research is getting ready for today’s task, which is to sedate wild reindeer and attach GPS collars for analysis of animal movement. An animal with aberrant behavior is noticed. On the ground, it is traced and found in a recumbent state, although this reindeer had not been hit with the sedative dart. After a few more minutes the animal died. Intrigued by this, the crew decides to submit the body to the Norwegian Veterinary Institute for a full necropsy.

对动物大脑中的样本进行了测试，以测试致命的脑病慢性浪费疾病（CWD），尽管当时，这种疾病在欧洲从未在北美闻名。实验室的结果是令人震惊的，该动物对CWD的测试呈阳性。

CWD是由王室引起的一种可传播的神经退行性疾病，该疾病是由正常prion蛋白的错误折叠构象构成的。在北美，CWD具有高度传染性，在许多方面与绵羊和山羊的古典草皮相似。由于其控制构成的巨大挑战，该疾病在北美无情地传播，并导致许多受影响地区的子宫颈人口下降（Devivo，Edmunds等人，2017年）。

The first detection of CWD in reindeer in Norway happened in March 2016, and the situation would rapidly go from bad to worse when two moose in the region of Selbu, about 300 kilometers from the reindeer case, came down positive for CWD during the spring. Three more cases were also detected in the reindeer population in which the first case was found.

Today, after five years, CWD has been diagnosed in 20 wild reindeer, eight moose and two red deer in Norway as well as in four moose in Sweden and two in Finland.

挪威政府决定夺取受影响的驯鹿人口。对所有动物（约2400只动物）进行了淘汰并测试了CWD，并确定了18例新病例。此后，包括成千上万的野生和半驯化的驯鹿在内的宫颈的全面监测没有发现新病例，直到2020年野生驯鹿雄鹿测试阳性。这只动物是在Hardangervidda的常规狩猎期间被枪杀的，该动物位于西欧占领的人口以南约70公里处，是西欧最大的野生驯鹿人口的中心，计算了约7-9万只动物。

显然，野生挪威驯鹿中的CWD并未通过最初的淘汰而被淘汰。

Prion diseases affecting ruminants are generally grouped as either classical or atypical (Tranulis, Benestad et al. 2011). Classical scrapie affecting sheep and goat is contagious, transmitting horizontally among animals through direct contact or via shared environments. In contrast, the atypical forms are considered to affect single, old animals, the infectious prions are restricted to the nervous system and are not shed to the surroundings in sufficient amounts for disease transmission.

确实，挪威野生驯鹿中CWD的形式具有感染性的所有主要特征。在免疫器官的中枢神经系统之外发现了感染性prions，不同年龄类别的动物受到影响（Benestad，Mitchell等，2016）。

对驼鹿病例的调查给出了截然不同的结果。在这里，未在大脑外发现毒品，所有受影响的动物都超过10岁。挪威，瑞典和芬兰的14个CWD病例的平均年龄接近15岁。

Studies in laboratory rodents, allowing strain typing of prions, have shown that the prions affecting reindeer and moose in Norway are different from each other and from those characterized in North America (Pirisinu, Tran et al. 2018, Nonno, Di Bari et al. 2020). Thus, recent trans-Atlantic transfer of CWD prions appears not to be the reason for emergence of CWD in Europe.

How about the two cases in red deer – are they linked to the reindeer cases? No, these are tentatively grouped as atypical CWD, like the moose cases, although the disease features and prion strain characteristics differ from that in moose.

因此，在仅五年的时间内，在北欧的三种子宫颈物种中发现了CWD。在驼鹿和红鹿中，该疾病可能以所谓的非典型形式偶发地发生，而在驯鹿中，这种疾病特征更像是在北美观察到的，具有水平传播。

在电流中reviewinActa Veterinaria Scandinavicaour aim is to provide the readers with an update of the situation, highlighting data on disease presentation and variation among prion isolates. It appears that at least three previously unrecognized prion strains are present in Northern Europe. Understanding the epidemiology, including the zoonotic potential of these agents is a major area of investigation and will remain so for years to come.

参考

Benestad, S. L., G. Mitchell, M. Simmons, B. Ytrehus and T. Vikoren (2016). “First case of chronic wasting disease in Europe in a Norwegian free-ranging reindeer.”Vet Res47(1): 88.

Devivo，M。T.，D。R. Edmunds，M。J. Kauffman，B。A. Schumaker，J。Binfet，T。J. Kreeger，B。J. Richards，H。M. Schatzl和T. E. Cornish（2017）。“流行的慢性浪费疾病会导致怀俄明州的m子鹿种群下降。”Plos One12（10）。

Nonno, R., M. A. Di Bari, L. Pirisinu, C. D’Agostino, I. Vanni, B. Chiappini, S. Marcon, G. Riccardi, L. Tran, T. Vikoren, J. Vage, K. Madslien, G. Mitchell, G. C. Telling, S. L. Benestad and U. Agrimi (2020). “Studies in bank voles reveal strain differences between chronic wasting disease prions from Norway and North America.”Proc Natl Acad Sci U S A117(49): 31417-31426.

Pirisinu，L.，L。Tran，B。Chiappini，I。Vanni，M。A. Di Bari，G。Vaccari，T。Vikoren，T。Vikoren，K。I. Madslien，J。Vage，J。Vage，T。Spraker，G。Mitchell，G。Mitchell，A。Balachandran，T。Baron，C。Casalone，C。M。Rolandsen，K。H。Roed，U。Agrimi，R。Nonno和S. L. Benestad（2018）。“挪威的驼鹿（Alces Alces）中检测到的新型慢性浪费疾病。”新兴感染疾病24（12）：2210-2218。

Tranulis，M。A.，S。L. Benestad，T。Baron和H. Kretzschmar（2011）。“人类和动物中的非典型王室疾病。”顶级化学305: 23-50.