Hestvik G, Uhlhorn H, Södersten F, Åkerström S, Karlsson E, Westergren E, Gavier-Widén D
Department of Pathology and Wildlife Diseases, National Veterinary Institute, Uppsala, Sweden; Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Department of Pathology and Wildlife Diseases, National Veterinary Institute, Uppsala, Sweden.
J Comp Pathol. 2017 Aug-Oct;157(2-3):103-114. doi: 10.1016/j.jcpa.2017.06.003. Epub 2017 Jul 25.
Tularaemia is an emerging zoonotic infectious disease caused by the bacterium Francisella tularensis. In Sweden, hares are considered to be key species in the epidemiology of tularaemia. The aim of this study was to characterize the pathology of natural tularaemia infection in European brown hares (EBHs) (Lepus europaeus) and mountain hares (MHs) (Lepus timidus) in Sweden, in order to better understand the presentation of disease and the routes of infection, body dissemination and shedding of F. tularensis. During 2000-2013, 49 EBHs and 37 MHs were diagnosed with tularaemia. Enlargement of the spleen was seen in 80% of EBHs and 62% of MHs. Necrosis was often obvious in the bone marrow, liver, lung and spleen, but 30% of the hares had no lesions or minimal gross lesions. On microscopical examination of tissues from 27 EBHs and three MHs, necrosis was seen in the majority of samples of liver, spleen, bone marrow, lymph node and adrenal glands and was common in the lungs and brain meninges. Immunohistochemistry for Francisella spp. detected bacteria in association with necrosis and inflammation. In several cases, Francisella spp. were also found inside blood vessels, in the renal pelvis, in lactating mammary glands, in bronchioles and in the skin, associated with tick bites. Using quantitative polymerase chain reaction, two genotypes of F. tularensis subsp. holarctica were found; canSNP group B.6, all belonging to subgroup B.7, and canSNP group B.12. There were no differences in pathology between the genotypes. Our results indicate that the urinary tract and mammary glands are important routes for the shedding of F. tularensis. Hunters may not be aware of the risks of contracting tularaemia while handling hares, since infected hares do not always show noticeable gross lesions.
兔热病是一种由土拉弗朗西斯菌引起的新发人畜共患传染病。在瑞典，野兔被认为是兔热病流行病学中的关键物种。本研究的目的是描述瑞典欧洲棕兔（EBHs）（欧洲野兔）和山地兔（MHs）（林兔）自然感染兔热病的病理学特征，以便更好地了解疾病表现、感染途径、土拉弗朗西斯菌的体内播散及排出情况。在2000年至2013年期间，49只欧洲棕兔和37只山地兔被诊断患有兔热病。80%的欧洲棕兔和62%的山地兔出现脾脏肿大。骨髓、肝脏、肺和脾脏中常可见坏死，但30%的野兔无病变或仅有轻微肉眼可见病变。对27只欧洲棕兔和3只山地兔的组织进行显微镜检查时，在大多数肝脏、脾脏、骨髓、淋巴结和肾上腺样本中可见坏死，在肺和脑膜中也很常见。针对弗朗西斯菌属的免疫组织化学检测发现细菌与坏死及炎症相关。在几例病例中，还在血管内、肾盂、泌乳乳腺、细支气管和皮肤中发现弗朗西斯菌属，与蜱叮咬有关。使用定量聚合酶链反应，发现了两种土拉弗朗西斯菌亚种全北区基因型；canSNP B.6组，均属于B.7亚组，以及canSNP B.12组。不同基因型之间在病理学上无差异。我们的结果表明，尿路和乳腺是土拉弗朗西斯菌排出的重要途径。猎人在处理野兔时可能未意识到感染兔热病的风险，因为受感染的野兔并不总是表现出明显的肉眼可见病变。
