Departamento de Anatomía y Anatomía Patológica Comparadas, Universidad de Murcia, 30100 Murcia, Spain.
Departamento de Anatomía y Anatomía Patológica Comparadas, Universidad de Murcia, 30100 Murcia, Spain.
Vet Microbiol. 2014 Jun 25;171(1-2):139-46. doi: 10.1016/j.vetmic.2014.03.035. Epub 2014 Apr 3.
This study reports the performance of the single intradermal tuberculin (SIT) test and the interferon-gamma (IFN-γ) assay for Mycobacterium bovis in a cattle herd with high prevalence of paratuberculosis (PTB). A total of 58/350 animals were selected for necropsy based on one or more of the following criteria: positive to SIT, IFN-γ, a breeding cow that seroconverted to PTB and showed signs compatible with a wasting disease. Infection status was determined by post mortem diagnostic tests that included histopathology examination, mycobacterial cultures and PCR identification for M. bovis and Mycobacterium avium subsp. paratuberculosis (MAP). In 7/58 animals primary tuberculosis (TB) lesions, affecting only the retropharyngeal and/or mediastinal lymph nodes, were found; 3/7 animals were found SIT positive. PTB was confirmed in 35/58 animals, of which 30 had seroconverted and 14 had typical clinical signs. 45/58 animals were IFN-γ(+) using the most stringent criterion (cut-off point ≥ 0.05); however, IFN-γ test was only positive in 33 animals when using a higher threshold (cut-off point ≥ 0.1). Three animals co-infected also showed extensive TB and diffuse PTB lesions. These results show that the combined use of SIT and IFN-γ, as interpreted using official guidelines, detected all confirmed cases of TB. Individually, the sensitivity of the SIT was inadequate to diagnose TB-positive animals with an advanced stage of PTB. The large number of IFN-γ(+) animals with no visible TB lesion could be due, in part, to some protection conferred by prior infection with MAP.
本研究报告了在一个副结核病（PTB）高发牛群中单皮内结核菌素（SIT）试验和干扰素-γ（IFN-γ）检测在牛分枝杆菌中的性能。根据以下一个或多个标准，共有 58/350 头动物被选择进行剖检：SIT 阳性、IFN-γ 阳性、血清学转换为 PTB 的繁殖母牛并出现与消耗性疾病相容的迹象。感染状态通过包括组织病理学检查、分枝杆菌培养和牛分枝杆菌和禽分枝杆菌副结核亚种（MAP）的 PCR 鉴定在内的死后诊断测试来确定。在 7/58 头动物中发现了原发性肺结核（TB）病变，仅影响咽后和/或纵隔淋巴结；7 头动物中 3 头 SIT 阳性。在 35/58 头动物中证实了 PTB，其中 30 头血清学转换，14 头有典型临床症状。使用最严格的标准（截断值≥0.05），45/58 头动物 IFN-γ（+）；然而，当使用更高的阈值（截断值≥0.1）时，IFN-γ 检测仅在 33 头动物中阳性。3 头混合感染动物也表现出广泛的 TB 和弥漫性 PTB 病变。这些结果表明，联合使用 SIT 和 IFN-γ，并按照官方指南解释，可以检测到所有确诊的 TB 病例。单独使用时，SIT 的敏感性不足以诊断处于晚期 PTB 的 TB 阳性动物。大量无可见 TB 病变的 IFN-γ（+）动物可能部分归因于 MAP 先前感染赋予的一些保护作用。
