Peltier Sarah K, Brown Justin D, Ternent Mark, Niedringhaus Kevin D, Schuler Krysten, Bunting Elizabeth M, Kirchgessner Megan, Yabsley Michael J
* Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602.
J Parasitol. 2017 Oct;103(5):593-597. doi: 10.1645/17-26. Epub 2017 Jun 22.
Since the early 1990s there has been an increase in the number of cases and geographic expansion of severe mange in the black bear (Ursus americanus) population in Pennsylvania. Although there are 3 species of mites associated with mange in bears, Sarcoptes scabiei has been identified as the etiologic agent in these Pennsylvania cases. Historically, S. scabiei-associated mange in bears has been uncommon and sporadic, although it is widespread and relatively common in canid populations. To better understand this recent emergence of sarcoptic mange in bears in Pennsylvania and nearby states, we genetically characterized S. scabiei samples from black bears in the eastern United States. These sequences were compared with newly acquired S. scabiei sequences from wild canids (red fox [Vulpes vulpes] and coyote [Canis latrans]) and a porcupine (Erethizon dorsatum) from Pennsylvania and Kentucky and also existing sequences in GenBank. The internal transcribed spacer (ITS)-2 region and cytochrome c oxidase subunit 1 (cox1) gene were amplified and sequenced. Twenty-four ITS-2 sequences were obtained from mites from bears (n = 16), red fox (n = 5), coyote (n = 2), and a porcupine. The sequences from bear samples were identical to each other or differed only at polymorphic bases, whereas S. scabiei from canids were more variable, but 2 were identical to S. scabiei sequences from bears. Eighteen cox1 sequences obtained from mites from bears represented 6 novel haplotypes. Phylogenetic analysis of cox1 sequences revealed 4 clades: 2 clades of mites of human origin from Panama or Australia, a clade of mites from rabbits from China, and a large unresolved clade that included the remaining S. scabiei sequences from various hosts and regions, including sequences from the bears from the current study. Although the cox1 gene was more variable than the ITS-2, phylogenetic analyses failed to detect any clustering of S. scabiei from eastern U.S. hosts. Rather, sequences from black bears grouped into a large clade that included S. scabiei from numerous hosts from Europe, Asia, Africa, and Australia. Collectively, these data suggest that the increasing number of S. scabiei cases in northeastern black bears is not due to the emergence and expansion of a single parasite strain.
自20世纪90年代初以来，宾夕法尼亚州黑熊（美洲黑熊）种群中严重疥癣的病例数量有所增加，且地域范围不断扩大。虽然与熊疥癣相关的螨类有3种，但疥螨已被确定为宾夕法尼亚州这些病例的病原体。从历史上看，熊身上与疥螨相关的疥癣并不常见且呈散发性，尽管在犬科动物种群中广泛存在且相对常见。为了更好地了解宾夕法尼亚州及附近各州近期熊疥螨病的出现情况，我们对美国东部黑熊的疥螨样本进行了基因特征分析。将这些序列与新获得的来自宾夕法尼亚州和肯塔基州野生犬科动物（赤狐和郊狼）以及一只豪猪的疥螨序列，以及GenBank中的现有序列进行了比较。对内部转录间隔区（ITS）-2区域和细胞色素c氧化酶亚基1（cox1）基因进行了扩增和测序。从熊（n = 16）、赤狐（n = 5）、郊狼（n = 2）和一只豪猪身上的螨类获得了24个ITS-2序列。熊样本的序列彼此相同或仅在多态性碱基处有所不同，而犬科动物的疥螨序列更具变异性，但有2个与熊的疥螨序列相同。从熊身上的螨类获得的18个cox1序列代表了6种新的单倍型。cox1序列的系统发育分析揭示了4个分支：2个来自巴拿马或澳大利亚的人类源螨类分支，1个来自中国兔子的螨类分支，以及一个大型未解析分支，其中包括来自各种宿主和地区的其余疥螨序列，包括本研究中熊的序列。尽管cox1基因比ITS-2更具变异性，但系统发育分析未能检测到美国东部宿主的疥螨有任何聚类情况。相反，黑熊的序列聚集成一个大型分支，其中包括来自欧洲、亚洲、非洲和澳大利亚众多宿主的疥螨。总体而言，这些数据表明，东北部黑熊中疥螨病例数量的增加并非由于单一寄生虫菌株的出现和扩散。
