title: Interference of paratuberculosis with the diagnosis of tuberculosis in a goat flock with a natural mixed infection.
abstract: Detection of infected animals is a key step in eradication programs of tuberculosis. Paratuberculosis infection has been demonstrated to compromise the specificity of the diagnostic tests. However, its effect on their sensitivity has not been clarified. In the present study, skin tests and the interferon-gamma (IFN-gamma) assay were evaluated in a goat flock (n=177) with a mixed tuberculosis-paratuberculosis infection in order to assess the possible effect of paratuberculosis on their sensitivity. Culture of mycobacteria was performed as the gold standard to determine the true infection status. All techniques showed lower sensitivities than previously described; the single intradermal tuberculin (SIT) test and the IFN-gamma assay detected 71% (62.4-78.6, 95% C.I.) of the infected animals; the single intradermal cervical comparative tuberculin (SICCT) test detected only 42.7% (34.1-51.7, 95% C.I.) of infected animals. The highest level of sensitivity was obtained when SIT test and IFN-gamma assay were combined in parallel (90.8%, 84.5-95.2, 95% C.I.). Sensitivities of the tests were also assessed by comparing animals suffering tuberculosis and animals with a mixed infection; tests were found to be more effective in the former group. Paratuberculosis seems to have a major effect in the sensitivity of the diagnostic tests under study, and therefore must be taken into account; in particular, the use of the SICCT test should be questioned when both tuberculosis and paratuberculosis are present.
authors.affiliation: Laboratorio Visavet, Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Julio
authors.initials: J
authors.lastname: Alvarez
authors.forename: Lucía
authors.initials: L
authors.lastname: de Juan
authors.forename: Javier
authors.initials: J
authors.lastname: Bezos
authors.forename: Beatriz
authors.initials: B
authors.lastname: Romero
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Sáez
authors.forename: F J
authors.initials: FJ
authors.lastname: Reviriego Gordejo
authors.forename: Víctor
authors.initials: V
authors.lastname: Briones
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Moreno
authors.forename: Ana
authors.initials: A
authors.lastname: Mateos
authors.forename: Lucas
authors.initials: L
authors.lastname: Domínguez
authors.forename: Alicia
authors.initials: A
authors.lastname: Aranaz
mesh_terms: D000818:Animals; D015511:Goat Diseases / Q000175:diagnosis* / Q000276:immunology; D006041:Goats; D007371:Interferon-gamma / Q000097:blood; D009161:Mycobacterium / Q000302:isolation & purification*; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification; D010283:Paratuberculosis / Q000150:complications*; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D014374:Tuberculin Test / Q000379:methods / Q000592:standards / Q000662:veterinary*; D014376:Tuberculosis / Q000150:complications / Q000175:diagnosis / Q000662:veterinary*
chemical_list: D007371:Interferon-gamma