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

Abstract

Tuberculosis pathology was studied on 19 African buffalo ( Syncerus caffer) from a herd in the Hluhluwe-iMfolozi Park in South Africa. The animals tested positive with the comparative intradermal tuberculin test and were euthanized during a test-and-cull operation to decrease prevalence of bovine tuberculosis (bTB) in the park. The lymph nodes and lungs were examined grossly for presence of tuberculous lesions, which were scored on a 0–5 scale for macroscopic changes. The gross lesions were examined histologically and classified into grade I, II, III, or IV according to a grading system used for bTB lesions in domestic cattle. Macroscopic lesions were limited to the retropharyngeal, bronchial, and mediastinal lymph nodes and the lungs. The most frequently affected lymph nodes were the bronchial (in 16 animals) and mediastinal (in 11 animals). All four grades of microscopic lesions were observed, grade II lesions were the most frequent. Mycobacterium bovis was detected by PCR in 8 out of 19 animals, and acid-fast bacilli were seen in 7 out of 19 animals, together both techniques identified mycobacteria in 5 out of 19 animals. Lesions were paucibacillary, as acid-fast bacilli were only rarely observed. The absence of lesions in the mesenteric lymph nodes and the high frequency of lesions in respiratory tract associated lymph nodes suggest that the main route of M. bovis infection in African buffalo is by inhalation.

Wildlife Reservoirs of Bovine Tuberculosis Worldwide: Hosts, Pathology, Surveillance, and Control

“…A recently published survey of 19 African buffalo that tested positive by intradermal tuberculin testing and were culled from Hluhluwe-iMfolozi Park described the BTB lesions present. 22 Gross lesions in 80% of these buffalo were restricted to the retropharyngeal, bronchial, and mediastinal lymph nodes, whereas only 20% of tuberculous buffalo had gross lesions in their lungs. 22 This lesion distribution suggests that the primary route of infection in buffalo is by inhalation.…”

Diagnóstico histopatológico e molecular de lesões sugestivas de tuberculose em búfalos abatidos nos municípios de Macapá e Santana, estado do Amapá

“…A tuberculose pulmonar observada na maioria dos bubalinos do presente estudo é relatada como a forma mais comum da doença em búfalos (Freitas et al 2001, Laisse et al 2011. De forma semelhante, Albernaz et al (2015) observaram lesões sugestivas de tuberculose em linfonodos mediastínicos, além de achados macroscópicos em linfonodos mesentéricos de bubalinos.…”

“…As lesões histológicas foram semelhantes às observadas por Kanameda & Ekgatat (1995), Laisse et al (2011), Albernaz et al (2015) na tuberculose bubalina, mantendo grande similaridade aos granulomas tuberculosos descritos na espécie bovina (Cancela & Marín 1993, Cassidy et al 1999, Wangoo et al 2005, Watrelot-Virieux et al 2006, Varello et al 2008. A detecção de bacilos álcool-ácido resistentes (BAAR) em somente três búfalos demonstra a baixa sensibilidade da técnica, uma vez que 13 animais apresentaram resultados positivos nas técnicas de Nested-PCR.…”

“…A detecção de bacilos álcool-ácido resistentes (BAAR) em somente três búfalos demonstra a baixa sensibilidade da técnica, uma vez que 13 animais apresentaram resultados positivos nas técnicas de Nested-PCR. A baixa sensibilidade da coloração de Ziehl-Neelsen é relatada em bubalinos (Garine-Wichatitsky et al 2010, Laisse et al 2011) e em bovinos (Cancela & Marín 1993, Sulieman & Hamid 2002, Watrelot-Virieux et al 2006. Um animal que apresentava BAAR foi negativo aos testes moleculares.…”

“…Em outro estudo, a identificação do CMT em tecidos bovinos e bubalinos, por meio de Nested-PCR, alcançou sensibilidade clínica de 76,7% e especificidade máxima (100%), índices superiores à PCR convencional e cultura (Araújo et al 2014a). Percentuais superiores aos descrito por Laisse et al (2011), que encontraram 42,1% (8/19) de positivos para M. bovis em búfalos africanos empregando kit comercial de amplificação simultânea para CMT e CMA.…”