Use of commercial ELISA for the diagnosis of bovine tuberculosis in animals negative in the intradermal tuberculin test

Tuberculosis is a globally distributed infectious disease of great importance to public health due to its zoonotic nature. In addition to its major impact on public health, bovine tuberculosis causes major economic losses due to reduced herd productivity and carcass losses in slaughterhouses. Given the critical importance of the disease, it is of utmost importance to enhance the accuracy of diagnostic methods in programs aimed at controlling and eradicating bovine tuberculosis in Brazil. The objective of this research project is to diagnose bovine tuberculosis in dairy herds that previously tested negative in the intradermal tuberculin test using commercial ELISA (enzyme-linked immunosorbent assay). Samples from 17,917 cattle from dairy herds distributed across five farms in the Campos Gerais region of the state of Paraná were analyzed. For serological diagnosis, the commercial ELISA/IDEXX® kit was used to detect anti-Mycobacterium bovis antibodies in cattle herds. Of the 17,917 animals tested, the ELISA Mycobacterium bovis Antibody Test (IDEXX®) identified 399 (2.3%) reactive animals and 17,518 (97.7%) non-reactive animals. The highest number of positive animals in the ELISA was observed on farm B, with 375 (2.5%) reactive animals. Given the challenges faced in Brazil regarding the diagnostic confirmation of tuberculosis and the absence of validated reagents and methods, the importance of implementing new validated diagnostic methods is evident. The use of ELIST could serve as a complementary alternative to the official intradermal tuberculin test, potentially detecting false-negative animals and aiding in the control of the disease.