利用血液檢體偵測台灣牛隻及鹿隻的牛型結核病

Abstract

皮內結核菌素檢測為台灣牛型結核病的官方檢驗方法。皮內結核菌素檢測是一種細胞免疫反應，過程中動物體需要接受兩次的保定方能完成此檢驗，對於馴化非良好的動物如鹿及野生動物有因緊迫造成損失的疑慮。此外，重複施行皮內結核菌素試驗必須間隔三個月，此等待期成為控制及撲滅疾病的重大缺點。使用血液樣本執行酵素聯結免疫吸附法或是聚合酶鏈鎖反應，也許可以彌補皮內結核菌素檢驗的缺點。本實驗中，從牛隻與鹿隻收集血液，進行聚合酶鏈鎖反應與酵素聯結免疫吸附法，血液檢測結果與培養、病理學及組織聚合酶鏈鎖反應的結果互相比較。若以培養結果當作金標準，147頭皮內結核菌素檢測陽性牛，其周邊血液單核細胞聚合酶鏈鎖反應敏感性為7.7% (2/26)，特異性為95.0% (115/121)；酵素連結免疫吸附法敏感性為0% (0/26)，特異性為95.0% (115/121)，可知牛結核病血液檢測具低敏感性及高特異性的特徵。在相同條件下，20頭鹿隻的周邊血液單核細胞聚合酶鏈鎖反應，其結果顯示此法不具敏感性(0%，0/7)但有高特異性(100%，7/7)；酵素聯結免疫吸附法則有高敏感性(85.7%，6/7)及中等特異性(50%，5/10)，且ELISA與皮內結核菌素試驗與培養結果的相關係數皆為0.647(屬於中等吻合度)，且血液試驗是實施一次保定即可採集及檢體的方式，不若結核菌素需要兩次保定，可避免馴化非良好的鹿隻因強大持續緊迫造成損失。因此，血液試驗在乳牛清除結核病有敏感性過低的疑慮，然而對於檢測鹿隻牛型結核病感染，血液試驗具有清楚的效益。

Intradermal tuberculin test (ITT) is the official test for diagnosis of bovine tuberculosis in Taiwan. ITT is a cell-mediated immune response that acquires two times of restraint and handling the animal to complete the examination, and safety issue is always concerned in non-domestic animal like deer or wildlife to perform this test. In addition, repeated or confirmed ITT test in the previous ITT positive animal should be performed in three months later which results in a significant drawback in the aspect of disease control and eradication. Using blood samples to perform enzyme-linked immunosorbent assays (ELISAs) or polymerase chain reaction (PCR) may provide an alternative assay to correct the shortcomings of ITT. In this study, blood samples collected from cattle and deer were tested by PCR and ELISA, and the results were subsequently correlated with the results of pathology, microbiology and PCR in the tissue examined. Using culture results as the golden standard in 147 ITT positive cattle, the sensitivity of PCR in peripheral blood mononuclear cells (PBMC) was 7.7% (2/26) and the specificity was 95.0% (115/121), the sensitivity of the ELISA was 0% (0/26) and the specificity was 95.0% (115/121). Under the same conditions of 17 deer, the sensitivity of PCR in PBMC was 0% (0/7) and the specificity was 100% (10/10), the sensitivity of the ELISA was 85.7% (6/7) and the specificity was 50% (5/10). In deer, the correlation coefficient between ELISA and ITT was 0.647(substantial agreement), and the correlation coefficient between ELISA and culture was also 0.647 (substantial agreement). Therefore, the blood tests for Mycobacterium bovis infection in cattle maybe not so helpful; however, blood tests are effective to detect Mycobacterium bovis infection in deer.