Airborne Mycobacterium avium infection in a group of red-shanked douc langurs (Pygathrix nemaeus nemaeus)

Background This report describes an airborne Mycobacterium avium (MA)-infection in two red-shanked douc langurs (Pygathrix nemaeus nemaeus) from Cologne zoo. Methods The two individuals and their tissues were investigated clinically (including x-rays), in pathology, in pathohistology, in classical bacteriology and by polymerase chain reaction (PCR). Results Clinically, one individual displayed emaciation and a positive reaction in an intrapalpebral testing for M. bovis/MA. The other individual was without any symptoms and did not show any reaction in the intrapalpebral test. In x-ray photos of the lungs, calcified nodules were detected. In pathology, calcified and necrotic nodules were observed within the lungs and the bronchial lymph nodes. In pathohistology, both classical tuberculous granulomas, and few acid fast rods were seen in Ziehl-Neelsen-stain. However, classical bacteriology could not demonstrate mycobacteria. In PCR, MA-infection could be confirmed in one individual using the bronchial lymph nodes. Conclusions It was an airborne infection; however, the definite source of infection in these cases remained unclear. Animals in contact to the langurs (house sparrows and mice) as well as water used in the building are the most promising candidates. The risk for a zoonotic transmission in these cases has been calculated to be low.