Bovine tuberculosis in safari park in Brazil

Tuberculose bovina em parque safári no Brasil

ABSTRACT:

Bovine tuberculosis (bTB) is an infectious disease caused by Mycobacterium bovis, affecting domestic animals, wild animals and humans. In captivity, for wild animals, bTB represents a risk to animal keepers and zoo visitors, in addition to the possibility of spreading the infection to domestic animals or through the trade of infected wild animals. Sambar (Cervus unicolor), red deer (Cervus elaphus) and fallow deer (Dama dama) from a safari park in the State of Rio Grande do Sul, Brazil, showed a clinical condition of dyspnea and weight loss. Some animals died and showed lesions suggestive of tuberculosis (LST), which were confirmed by histopathology. After the interdiction of the safari park by the state veterinary authorities, 281 deer were euthanized with the authorization of the “Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis” (IBAMA). Retropharyngeal and submandibular lymph nodes and viscera were collected from 21 animals, which were grown in Stonebrink medium for up to 90 days. After DNA extraction from the bacterial colonies, PCR was performed for targets flanking the region of differentiation 4 (RD4). Of the 21 samples, 14 (66.7%) presented LST with a granulomatous appearance, a whitish coloration, and caseous or calcified consistency, and seven samples (33.3%), showed no lesions. In the culture of 14 samples with LST, 13 (92.8%) presented bacterial growth compatible with M. bovis. In the cultivation of the seven samples without LST, four (57.1%) presented colonies compatible with M. bovis. PCR and DNA sequencing of the PCR amplicons detected as positive all the 17 (100%) bacteriological cultures suggestive of M. bovis, thus confirming the outbreak of bTB in deer. Decisions about positive tested and suspicious animals should be taken based on the evaluation of the risk of transmission to the rest of the zoological animals, animal welfare, conservation considerations and, the zoonotic potential of this pathogen.

INDEX TERMS:
Bovine tuberculosis; Brazil; Mycobacterium bovis; zoonosis; PCR; deer; wildlife animals