Vet. Res. 37 (2006) 593-606
DOI: 10.1051/vetres:2006021

Assessment of diagnostic tools for eradication of bovine tuberculosis in cattle co-infected with Mycobacterium bovis and M. avium subsp. paratuberculosis

Alicia Aranaz^a, Lucía De juan^a, Javier Bezos^a, Julio Álvarez^a, Beatriz Romero^a, Francisco Lozano^a, José L. Paramio^b, Jesús López-Sánchez^c, Ana Mateos^a and Lucas Domínguez<sup>a

a</sup>  Departamento de Sanidad Animal I, Facultad de Veterinaria, Universidad Complutense de Madrid, Av. Puerta de Hierro s/n, 28040 Madrid, Spain
^b  Subdirección General de Sanidad Animal, Dirección General de Ganadería, MAPA, 28071 Madrid, Spain
^c  Laboratorio Regional Pecuario, Consejería de Agricultura, JCCM, 02071 Albacete, Spain

(Received 12 August 2005; accepted 31 January 2006; published online 16 May 2006)

Abstract - The intradermal tuberculin (IDTB) test and the interferon-gamma (IFN-) assay are used worldwide for detection of bovine tuberculosis in cattle, but little is known about the effect of co-infecting agents on the performance of these diagnostic tests. This report describes a field trial conducted in a cattle herd with dual infection (bovine tuberculosis and paratuberculosis) during 3.5 years. It has been based on a strategic approach encompassing serial parallel testing (comparative IDTB test, the IFN- assay and serology of paratuberculosis) that was repeated 8 times over the period, and segregation of animals into two herds. The IDTB test detected 65.2% and the IFN- test detected 69.6% of the Mycobacterium bovis culture-positive cattle. However, the IDTB test performed better during the first part of the trial, while the IFN- test was the only method that detected infected animals during the following three samplings. The number of false positive reactors with the IDTB and/or the IFN- tests was remarkably high compared to other reports, and could be caused by cross-reactivity with M. avium subsp. paratuberculosis. Also, the M. bovis isolates from cattle and wildlife from the same property were characterised using molecular techniques to disclose an epidemiological link. The IDTB test may not be appropriate to eradicate bovine tuberculosis in herds with dual mycobacterial infections. This report highlights the need to use several diagnostic techniques for the accurate detection of M. bovis infected animals in these herds.

Key words: tuberculosis / paratuberculosis / IDTB / IFN- / eradication

Corresponding author: Alicia Aranaz alaranaz@vet.ucm.es

© INRA, EDP Sciences 2006