College of Veterinary Sciences, Mekelle University, P.O. Box 2084, Mekelle, Ethiopia.
Department of Animal Sciences, Raya University, P.O. Box 42, Maichew, Ethiopia.
BMC Vet Res. 2020 Oct 7;16(1):375. doi: 10.1186/s12917-020-02582-2.
Epizootic lymphangitis (EL), caused by Histoplasma capsulatum variety farciminosum (HCF) is a contagious, chronic disease of equines, characterized by development of nodular lesions in the lymph nodes, lymphatic vessels and skin. It is one of the most important diseases of equines in Ethiopia, causing significant economic loss, particularly in the livelihood of carthorse owners. To date there is neither effective diagnostic nor control measure implemented in the country. Furthermore, there is a shortage of data on the epidemiology of the disease in different regions of this country. The aim of this study was to investigate epidemiology of EL in northern Ethiopia, using the conventional methods as well as nested polymerase chain reaction (PCR).
The presence of HCF genetic material was confirmed in 44% (84/191) of the carthorses. Subclinical infection was observed in 18.2% (22/121) of the apparently healthy carthorses. Considering the nested PCR as a gold standard, sensitivity and specificity of clinical examination were 74% and 92.5%, respectively, while the area under the ROC curve (AUR) was 0.83 (95% confidence interval, 0.77, 0.896). Moreover, a moderate (k = 0.675) agreement observed between the nested PCR and clinical examination.
This study demonstrated widespread occurrence of EL in northern Ethiopia, and the advantage of the nested PCR in detecting infection of HCF, even before the clinical symptoms became apparent.
由荚膜组织胞浆菌变种（Histoplasma capsulatum variety farciminosum，HCF）引起的流行性淋巴管炎（Epizootic lymphangitis，EL）是一种传染性、慢性马属动物疾病，其特征是在淋巴结、淋巴管和皮肤中形成结节性病变。它是埃塞俄比亚马属动物最重要的疾病之一，造成了巨大的经济损失，特别是对役马饲养者的生计造成了影响。迄今为止，该国既没有实施有效的诊断措施，也没有采取控制措施。此外，该国不同地区该病流行病学的数据也很匮乏。本研究旨在使用传统方法和巢式聚合酶链反应（nested polymerase chain reaction，PCR）调查埃塞俄比亚北部的 EL 流行病学。
在 191 匹役马中，有 44%（84/191）的马 HCF 遗传物质呈阳性。在 121 匹貌似健康的役马中，观察到亚临床感染的比例为 18.2%（22/121）。考虑到嵌套 PCR 为金标准，临床检查的敏感性和特异性分别为 74%和 92.5%，ROC 曲线下面积（area under the ROC curve，AUR）为 0.83（95%置信区间，0.77，0.896）。此外，嵌套 PCR 和临床检查之间观察到中度一致性（k=0.675）。
本研究表明，EL 在埃塞俄比亚北部广泛流行，并且嵌套 PCR 在检测 HCF 感染方面具有优势，甚至在临床症状出现之前就可以检测到。
