Institute of Parasitology, Justus Liebig University Giessen, 35392 Giessen, Germany.
Institute of Parasitology, Justus Liebig University Giessen, 35392 Giessen, Germany.
Vet Parasitol Reg Stud Reports. 2024 Jan;47:100948. doi: 10.1016/j.vprsr.2023.100948. Epub 2023 Nov 6.
Lamanema chavezi is one of the most pathogenic nematode species of South American camelids (SAC), with a homoxenous life cycle involving enterohepatic migration of its larvae in the host. So far, it has been found in the Americas and New Zealand. The first autochthonous L. chavezi infections in SAC in Europe are reported here. On a SAC farm in Germany, a 15-month-old male llama with a short history of diarrhoea died in September 2017, followed nine months later by a three-year-old female llama with a history of emaciation, apathy, anorexia, anaemia and tetraparesis with retained sensorium. Both animals were born and raised on the farm, which had imported three llamas directly from Chile 4-14 years earlier. At necropsy, the main lesions in both cases were numerous white-yellow to dark red foci, up to 3 mm in size, close to the Glisson's capsule and deep in the parenchyma of the liver. Histologically, the livers showed haemorrhagic tracks by and with nematode larvae and a necro-haemorrhagic to fibrinous inflammation with a predominantly lymphohistiocytic infiltration. The larvae were 30-50 μm in diameter and had external longitudinal cuticular ridges. Larvae extracted from unfixed liver tissue were 1800-2000 μm long and about 80 μm in diameter, with a terminal spine at the posterior end, which is characteristic of female L. chavezi stages. The ribosomal DNA including the almost complete 18S rRNA gene, the first internal transcribed spacer, the 5.8S RNA gene, the second internal transcribed spacer (ITS) and the partial 28S rRNA gene from isolated larvae were amplified using nematode-specific oligonucleotide primers and then sequenced. The assembled nematode sequence of 3448 bp showed an identity of 99.4% to previously published L. chavezi sequences in the BLASTN search. Low numbers of L. chavezi-like eggs were found in the faeces of seven (29%) of 24 llamas and alpacas in the herd, including some farm-born crias, tested two years after the last fatal case. The results show for the first time that L. chavezi has not only been imported into Europe from South America, but has also completed its life cycle locally, resulting in autochthonous infections of SAC. This was also suspected to be the cause of the fatal disease in two llamas.
查韦斯龙线虫是南美的骆驼科动物（SAC）中最具致病性的线虫物种之一，其幼虫具有在宿主中进行肠肝迁移的同生性生命周期。迄今为止，它已在美洲和新西兰被发现。本文首次报道了欧洲 SAC 中本地感染的查韦斯龙线虫。在德国的一个 SAC 农场中，一只 15 个月大的雄性羊驼因腹泻病史而死亡，随后 9 个月后，一只 3 岁的雌性羊驼出现消瘦、冷漠、食欲不振、贫血和四肢瘫痪，但意识保留。这两只动物均在该农场出生和饲养，该农场在 4-14 年前直接从智利进口了三只羊驼。剖检时，这两例的主要病变是大量白色至黄色至暗红色病灶，大小达 3mm，靠近 Glisson 囊，位于肝脏实质深部。组织学上，肝脏显示出带有和带有线虫幼虫的出血性痕迹，以及伴以坏死性出血至纤维蛋白性炎症，以淋巴细胞性组织细胞浸润为主。幼虫直径为 30-50μm，具有外部纵向角质层脊。从未固定的肝组织中提取的幼虫长 1800-2000μm，直径约 80μm，后端有一个末端刺，这是雌性查韦斯龙线虫阶段的特征。核糖体 DNA 包括几乎完整的 18S rRNA 基因、第一个内部转录间隔区、5.8S RNA 基因、第二个内部转录间隔区（ITS）和部分 28S rRNA 基因，均使用线虫特异性寡核苷酸引物扩增，并进行测序。组装的 3448bp 线虫序列在 BLASTN 搜索中与之前发表的查韦斯龙线虫序列的同一性为 99.4%。在该畜群中 24 只羊驼和骆马中，有 7 只（29%）的粪便中发现了少量查韦斯龙线虫样卵，其中包括一些农场出生的小羊驼，在最后一例致命病例发生两年后进行了检测。结果表明，查韦斯龙线虫不仅从南美洲进口到欧洲，而且还在当地完成了其生命周期，导致了 SAC 的本地感染。这也被怀疑是两只羊驼致命疾病的原因。
