Tuberculosis in captive lowland tapirs (Tapirus terrestris) from Brazil
Veterinary pathology, granulomatous pneumonia, histopathology, immunohistochemistry, Perissodactyla
Mycobacterium tuberculosis and Mycobacterium bovis are the causative agents of tuberculosis, a disease of great importance not only for public health, but also for animal health, since many animal species, such as the tapir (Tapirus terrestris), are susceptible to infection with these mycobacteria. In this context, the present study describes clinical pathological, immunohistochemical, bacteriological and molecular results of four fatal tuberculosis cases transmitted in tapirs kept under human care in Brazil. Of the total tapirs (n=4), two came from a zoo located in the state of Rio de Janeiro and two were from a zoo in the state of Goiás. The tapirs were subjected to necropsy, where tissues were found for histopathology, immuno- histochemistry (IHC), bacterial cultivation and molecular examination. To perform immunohistochemistry with a polyclonal antibody anti-M. tuberculosis, lung and lymph node sections were used. For bacterial cultivation and molecular analyses, bronchoalveolar lavage samples and non-inserted samples of lung and mediastinal lymph node tissue with granulomatous lesions were used. DNA extraction from the samples was performed using a commercial kit (QIAamp DNA Microbiome, QIAGEN) following the manufacturer's protocol. For DNA research of M. tuberculosis and M. tuberculosis var. bovis, the Polymerase Chain Reaction (PCR) was performed for fragments of the RD9 and TbD1 genes. In the clinical picture, the tapirs presented tachypnea, weakness, cough and mild weight loss. No nodular lesion typical of necrotic granulomas was disclosed. On histology, the nodules presented necrotic centers that destroyed the epithelium of the bronchi and bronchioles. In Ziehl-Neelsen staining, the samples were positive. In IHC with anti-M. tuberculosis, two cases were marked from Rio de Janeiro. In cell culture, growth of MTBC bacteria was observed in samples from two cases. Samples from all cases amplified the RD9 and TbD1 genes, suggesting that these animals were infected with a modern strain of M. tuberculosis. Given these findings, it is clear that tapirs are susceptible to tuberculosis caused by M. tuberculosis and M. bovis, which is why there is a need for more studies and surveillance to diagnose this disease in these animals that have direct contact with humans, as It is a zoonosis of great relevance.