An alert of Mycobacterium tuberculosis infection of rhesus macaques in a wild zoo in China

Mycobacterium tuberculosis, the pathogen that causes tuberculosis (TB), is becoming increasingly recognized as an important cause of fatal chronic illnesses in China. In this study, we report an infectious disease among 84 rhesus macaques at a Chinese zoo. Their clinical signs and symptoms were very similar with the manifestations of TB in humans. To determine the potential pathogens of this outbreak, many methods were used. First, tuberculin skin tests showed that none of the monkeys displayed significant skin reactions. Subsequently, the sera were tested for specific antibody IgG; 29 (34.5%) and 39 (46.4%) blood samples tested positive by TB-IgG and TB-DOT, respectively. Radiographic examination showed characteristic imageology changes in 14 (16.7%) monkeys. One individual determined as positive by the above three methods was euthanized, and histopathological analysis demonstrated typical granulomas and caseous necrosis in the lung, liver, spleen, and intestine. Furthermore, the pathogenic mycobacteria were isolated from lung lobe, cultured on acidic Lowenstein-Jensen culture medium, and identified as M. tuberculosis by real-time PCR and DNA sequencing. Nevertheless, the origin of the infection remained unknown. These findings emphasize the need to strengthen the management and training of staff, especially those working at animal shelters.