Antemortem and Postmortem Diagnoses of Bovine Tuberculosis in Southern Chad: Case of Slaughter Cattle

Abstract

Between July and November 2005, 919 cattle from migratory herds destined for slaughter in Sarh (Chad) were examined antemortem and postmortem to identify animals suspected of bovine tuberculosis (BT). The animals belonged to two main local breeds, Arab (639) and Mbororo (280), comprised 595 females and 324 males, aged 1 to 11 years, and were divided into four age groups. Antemortem clinical examination and single intradermal comparative cervical tuberculin (SICCT) tests were performed. The postmortem diagnosis (PMD) consisted in the inspection at the slaughterhouse and microscopy for the detection of acid-fast bacilli (AFB). SICCT revealed 95 positive reactors (10.3%) and 102 doubtful results (11%). Furthermore, 109 carcasses (offal) were suspected of tuberculosis and the lesions collected, processed and stained with Ziehl- Neelsen, contained AFB in 47.7% cases only. SICCT and PMD both showed susceptibility to BT of the Mbororo breed as well as of animals aged 4 to 9 years. Despite the discrepancy between the two diagnosis methods, the combined results served to identify 130 cases in the sample tested, of which half were aged 7 to 9 years.