Study on supplemental test to improve the detection of bovine tuberculosis in individual animals and herds

Abstract

Background Bovine tuberculosis (bTB), is a worldwide disease caused by Mycobacterium bovis (M. bovis). The success of bTB eradication and control programs is based on early detection and the removal of reactors from a herd thus routine testing and cull strategy have been applied globally. Since the late nineteenth century, the Tuberculin Skin Test (TST) has been the primary antemortem test available to support bTB eradication campaigns. Due to the TST limitations in terms of Se and Sp, the credibility of the diagnosis is frequently questioned given the occurrence of false-positive and false-negative reactions, therefore, it is necessary to confirm reactive animals using other methods, ensuring the reliability of the diagnosis. The aim of this study was to evaluate the sensitivity and specificity of a multiplex enzyme-linked immunosorbent assay (ELISA) relative to the tuberculin test used for the diagnosis of tuberculosis in cattle in Brazil. Results Lack of agreement between comparative cervical tuberculin test and ELISA IDEXX TM was observed. The 2 animals positive on the comparative cervical tuberculin test did not react at the ELISA IDEXX TM and 22 negative reactors by comparative cervical tuberculin test were positive by the ELISA IDEXX TM. The ELISA IDEXX TM showed sensitivity that is significantly lower than the official screening test the single cervical tuberculin. ELISA IDEXX TM also detected infected animals and herds undetected by the comparative cervical tuberculin test. The parallel use of comparative cervical tuberculin test and ELISA IDEXX TM increased sensitivity and the feasibility bTB screening. Conclusions The results obtained here suggest that the ELISA IDEXX TM may be a supplemental test for the detection of Mycobacterium bovis infection in regions without routine testing and slaughter, where the disease generally progresses to more advanced stages and antibody responses are likely to be more prevalent. Evidence to support the validation of the ELISA IDEXX™ as a supplemental test for bTB eradication programs was provided.

An ELISA test using a circulating Mycobacterium bovis peptide for detecting bovine tuberculosis in dairy cattle

“…These findings together with the scientific principles of these two diagnostic tests, ELISA and CFT are two independent tests. Application of using ELISA and CFT together as multiple tests for the diagnosis of bTB can be beneficial, especially when they are applied as parallel tests, which can increase the sensitivity of the bTB diagnosis in current bTB control and eradication programs ( 6 , 20 ).…”

What is the scope for existing (including recently developed) diagnostic methods to detect infected cattle which are not currently detected by the existing programme?

“…28. In general, antibody-based tests such as ELISA correlate more with lesion severity rather than early infection and their highest performance is usually reported in cattle with visible gross TB-lesions [13,[69][70][71]. This can have the beneficial result of detecting animals at more advanced stages of infection [72] that otherwise could potentially continue to spread TB.…”

“…This can have the beneficial result of detecting animals at more advanced stages of infection [72] that otherwise could potentially continue to spread TB. However, the sensitivity of ELISA antibody detection is generally lower than for tests targeting the DTH response [47] although that will also depend on the stage of disease in the cattle population, the type of DTH test that is performed and the tuberculin used for the test [69]. The application of an ELISA test after a skin test increases the sensitivity of the test [19,21].…”

Development of a monoclonal antibodies-based interferon-gamma enzyme-linked immunosorbent assay (ELISA) for rapid and accurate diagnosis of bovine tuberculosis

“…The test involves intradermal injection of tuberculin, a poorly de ned protein preparation from Mycobacterium cultures, into animals and subsequent detection of swelling and induration at the site of infection two or three days later [9]. This test, however, can lack both sensitivity and speci city [10][11][12][13][14][15]. Also, this test has many known limitations including di culties in administration and interpretation of results, need for a second-step visit, low degree of standardization, and imperfect test accuracy.…”