Characterization of tuberculous lesions in naturally infected African buffalo (Syncerus caffer)

[摘要] ENGLISH ABSTRACT: Mycobacterium bovis has a wide host range and infects many wild and domestic animalspecies as well as humans. African buffalo (Syncerus caffer) is considered to be a wildlifereservoir of M. bovis in certain environments in South Africa, such as in the KrugerNational Park (KNP) and Hluhluwe-iMfolozi Park (HiP).A detailed pathological study was conducted on 19 African buffalos (Syncerus caffer)from a herd in the HiP in South Africa. The animals tested positive to the intradermalbovine tuberculin test and were euthanazed during a test-and-cull operation to decreasethe prevalence of bovine tuberculosis (bTB) in the park. The superficial, head, thoraxicand abdominal lymph nodes and the lungs were examined grossly for presence oftuberculous lesions and were scored on a 1-5 scale for macroscopic changes. The grosslesions were examined histologically and scored I-IV according to a grading system usedfor bTB lesions in domestic cattle. Macroscopical lesions were limited to theretropharyngeal, bronchial, and mediastinal lymph nodes and the lungs. The mostfrequently affected lymph nodes were the bronchial (16/19) and mediastinal (11/19). Allfour grades of microscopic lesions were observed, although grade II lesions were themost frequent. Acid-fast bacilli were observed only rarely. Bovine tuberculosis wasconfirmed by PCR analyses.All animals were in good body condition and most of the lesions were in an early stage ofdevelopment, indicating an early stage of the disease. The absence of lesions in themesenteric lymph nodes and the high frequency of lesions in respiratory tract associatedlymph nodes suggest that the main route of M. bovis infection in African buffalo isinhalatory rather than alimentary. This study presents a systematic evaluation and semiquantificationof the severity and stages of development of tuberculous lesions in buffalo.The results may contribute to i) the understanding of the pathogenesis of the disease, ii)the evaluation of experimental models of M. bovis infection in Syncerus caffer, and iii)the interpretation of pathological data from vaccination trials.

[发布机构] Stellenbosch University