Carmel L. Witte1; Laura L. Hungerford2; Rebecca Papendick1; Ilse Stalis1; Bruce A. Rideout1
The objective of this study was to identify factors associated with avian mycobacteriosis in a population of captive birds. Inventory and necropsy records from all eligible birds in the collection of the Zoological Society of San Diego (ZSSD) from 1991–2005 (n=13,976) were examined to identify birds with post-mortem evidence of avian mycobacteriosis (n=172; 1.2%). A nested case-control study was conducted to identify and evaluate risk factors describing demographic, temporal, seasonal, and enclosure characteristics, along with move and exposure histories. One-hundred sixty-seven disease-positive birds (cases) were matched in a 1:7 ratio with 1169 disease-negative birds of similar age and taxonomic grouping. Risk factors were evaluated using univariate and multivariate conditional logistic regression analyses. Four factors were significantly associated with the diagnosis of avian mycobacteriosis in the multivariate model. Case birds were more likely than controls to have been previously housed with a bird with mycobacterial infection involving the intestinal tract (Odds ratio (OR)=5.5, p<0.01) or involving only nonintestinal sites (OR=2.2, p<0.01). Cases were more likely to have been imported into the collection than hatched at the ZSSD (OR=4.5, p<0.01). Birds that were frequently moved among ZSSD enclosures (>3 times) were more likely to have disease than birds that moved less (OR=2.6, p<0.01). Identification of characteristics of birds with avian mycobacteriosis will help guide future management of this disease for captive bird populations.