Tuberculosis Lesions of Bovine Carcasses in Algerian Municipal Abattoirs and Associated Risk Factors

Abstract

Bovine tuberculosis (bTB) is a transmissible disease of livestock with high economic consequences. To estimate the prevalence and risk factors associated to bTB, a study was conducted in Algerian abattoirs involving detailed inspection, microscopic examination, culture of tissue samples and molecular investigation. Out of 3848 bovine carcasses examined, 184 (4.78%) exhibited visible lesions suggestive of tuberculosis (TB). Anatomically 84.8% of the lesions were found in thoracic cavity. Lesions were predominant in tracheobronchial lymph nodes (71.7%), lung tissue (4.9%) and retropharyngeal lymph nodes (4.9%), followed by hepatic tissue (3.8%) and retrohepatic lymph nodes (3.8%). Less frequently, lesions were observed in prescapular lymph nodes (1.6%), digestive tract (0.5%) and kidney (0.5%). The study revealed statistically high (p<0.0001) infection rate in males (78.8%) than females (21.2%). A Significant difference (p<0.05) in TB infection rate was recorded between the three age/animal categories: 2 to 6 years (42.9%), <2 years (39.1%) and ≥6 years (17.9%). Analysis of data recorded in the present study showed a high significant variation (p<0.0001) in seasonal prevalence of bTB with a higher frequency during dry season than in rainy season. Microscopic examination of 105 samples revealed that 60 (57.1%) harbored acid-fast-bacilli (AFB) and 45(42.9%) were negative (p˃0.05). Culture yielded 60 (57.1%) positive, 43(41%) negative and only 2(1.9%) samples were contaminated. In PC RD9 analysis, all isolated strains were belong to the Mycobacterium tuberculosis complex (MTC). The present findings can serve as background information to elaborate an adequate eradication program for bTB in Algeria.