Mycobacterium avium complex and Mycobacterium genavense are generally responsible for mycobacteriosis in birds, especially when they are immunosuppressed.2,4,10 Avian mycobacteriosis has been reported in several bird species with varying clinical signs.2,4-8 Diagnosis comprises clinical examination, conventional microbiology and molecular methods that are not always available.1,10,11 There is a growing concern about this infectious disease given its increase among immunocompromised people and its impact on bird species. We report two mycobacteriosis cases in stygian owls (Asio stygius) caused by M. avium, a mycobacteria species not reported before for this avian species in Neotropical conditions.3
Two free-ranging stygian owls were found at the Universidad Nacional de Colombia (elevation: 2640 meters) in Bogota, Colombia, but died after several days of treatment. Clinical examination, necropsy, and sampling of liver tissue for hematoxylin-eosin histologic staining, Ziehl-Neelsen staining, hsp65 gene molecular analysis and sequencing of 16S rRNA gene were conducted. No isolate was obtained in cultures. The necropsy revealed yellowish nodules adhered to the costal surface of the thoracic portion of coelom, in the liver, and in the lungs. Hematoxylin-eosin-stained liver tissues showed chronic granulomatous lesions, and Ziehl-Neelsen staining revealed alcohol-acid resistant bacilli. No characteristic restriction patterns were obtained through molecular methods, but by sequencing the bacilli were identified as M. avium, a mycobacteria species not reported before in this avian species in Neotropical conditions. Molecular methods enable microorganism species identification when microbiologic confirmation is not possible.1,11 Avian mycobacteriosis cases should be reported to adopt measures aimed at preserving wildlife and human health.2,9
Acknowledgments to Claudia Castro, Martha Moreno y Derly Fierro for their support at mycobacteria, pathology and microbiology laboratory, respectively. To the Instituto Nacional de Salud (INS) de Colombia, Universidad Nacional de Colombia y Asociación de Veterinarios de Vida Silvestre (VVS) for funding.
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