Post-mortem examination and laboratory-based analysis for the diagnosis of bovine tuberculosis among dairy cattle in Ecuador

• Published in: Preventive veterinary medicine Vol. 101; no. 1; pp. 65 - 72
• Main Authors: Proaño-Pérez, Freddy, Benitez-Ortiz, Washington, Desmecht, Daniel, Coral, Marco, Ortiz, Julio, Ron, Lenin, Portaels, Françoise, Rigouts, Leen, Linden, Annick
• Format: Journal Article Web Resource
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2011; Elsevier Scientific
• Subjects: Abattoirs; Animals; Autopsy - veterinary; bovine tuberculosis; Cattle; culture media; dairy cattle; Ecuador - epidemiology; histopathology; In vitro culture; lesions (animal); Life sciences; Lung - microbiology; microscopy; Mycobacterium bovis; Mycobacterium bovis - isolation & purification; Médecine vétérinaire & santé animale; PCR; polymerase chain reaction; Polymerase Chain Reaction - veterinary; Sciences du vivant; slaughterhouses; Tuberculosis, Bovine - diagnosis; Tuberculosis, Bovine - epidemiology; Veterinary inspection; Veterinary medicine & animal health; Ecuador; Veterinary inspection; In vitro culture; Mycobacterium bovis; PCR
• ISSN: 0167-5877; 1873-1716; 1873-1716
• DOI: 10.1016/j.prevetmed.2011.04.018

Veterinary inspection in slaughterhouses allows for the detection of macroscopic lesions reminiscent of bovine tuberculosis, but the presence of Mycobacterium bovis must be confirmed by laboratory methods. This study aimed at comparing the performances of the standard diagnostic tools used to identify M. bovis in tissue specimens sampled from suspicious animals. During a two years period, 1390 cattle were inspected at the Machachi abattoir in the Mejia canton – Ecuador. A total of 33 animals with granulomatous lesions were detected, representing 2.33% (16/687) and 2.42% (17/703) animals examined in 2007 and 2008, respectively. Ninety-four tissue specimens were sampled and screened for the presence of mycobacteria. Acid-fast bacilli were identified in one third of the suspicious cattle (11/33) and suggestive microscopic lesions in 27.3% (9/33) of the samples examined by direct microscopy and histopathology, respectively. Culturing on Stonebrink medium and 16S-rRNA-based polymerase chain reaction (PCR) yielded 36.4% (12/33) and 27.3% (9/33) of positives, respectively. Compared to culture, other diagnostic procedures displayed a lower sensitivity, with 56.5% for PCR, and 43.5% for direct microscopy and histopathology; however, the specificity was higher (94.4% for PCR and microscopy, and 97.2% for histopathology). We conclude that reliable post-mortem laboratory testing either requires the combination of a set of available diagnostic tools or necessitates the development of improved new-generation tools with better sensitivity and specificity characteristics.