Serological diagnosis of tuberculosis in cattle. Behaviour of ELISA in animals naturally infected with Mycobacterium bovis and M. paratuberculosis
1993
Cavirani, S. | Flammini, C.F. | Allegri, G. (Parma Univ. (Italy). Istituto di Malattie Infettive) | Ansuini, A. | Arrigoni, N. (Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia, Brescia (Italy)) | Cavalca, M. (Unita Sanitaria Locale (U.S.L.), 5 - Fidenza, Parma (Italy)) | Magnani, R. (Unita Sanitaria Locale (U.S.L.), 4 - Parma (Italy))
An indirect ELISA was performed to obtain a serological test for the diagnosis of tuberculosis in cattle. Tests were carried out in 474 serum samples from animals reared in healthy and infected herds as demonstrated through intradermal tuberculin test with bovine, avian PPD and johnin. Among sera tested at 1/40 dilution, 163 resulted positive with one antigen, 35 with two and 39 with three ones. End point titration of samples positive with more than one antigen allowed to demonstrate specific reactivity in 148 sera, while in 15 the specificity could not be determined. The results showed concordance between tuberculin test and ELISA on a herd basis. However an obstacle to apply ELISA for the diagnosis of tubercolous infection seems to be produced by the high prevalence of subclinical paratuberculosis which apparently decreases the sensitivity of ELISA carried out in sera at costant dilution
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