|In order to compare different tuberculosis diagnostic tests and to reach disease confirmation, a study was performed in a group of 14 steers of Friesian breed, reacting positively to tuberculin test.
Three ante-mortem assays were performed according to the type of sample: the gamma interferon (IFN-Â¦Ã) test (which quantifies the release of this cytokine by sensitized lymphocytes in whole blood in response to purified protein derivative (PPD) and recombinant ESAT-6 and CFP10 proteins); PCR and bacteriologic culture from nasal swab and intradermal tuberculin test.
These assays were taken at different times to assess the evolution of clinical parameters. Post-mortem examination showed macroscopic and microscopic tuberculosis lesions with acid-fast bacillus and positive cultures.
By spoligotyping, we observed that all the isolates showed the same pattern.
The positive results based on comparison to lesions observed ranged from 58% to 75% for the IFN-Â¦Ã assays, to 72% for cultures, and ranged from 50% to 90% for PCR in nasal swabs.
In conclusion, in a herd infected by the same strain, ante-mortem direct and immune-diagnostic parameters change, suggesting that several tests are needed for a faster control of infection at herd level.
Source: V. Meikle, M. Schneider, G. Azenzo, M. ZumÂ¨Â¢rraga, G. Magnano, A. Cataldi (2007): Individual Animals of a Cattle Herd Infected with the Same Mycobacterium bovis Genotype Shows Important Variations in Bacteriological, Histopathological and Immune Response Parameters. In: Zoonoses and Public Health 54 (2), 86Â¨C93.
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