Investigation of factors predicting disease among zoo birds exposed to avian mycobacteriosis.
OBJECTIVE
To characterize infection patterns and identify factors associated with avian mycobacteriosis among zoo birds that were housed with infected enclosure mates.


METHODS
Matched case-control study.


METHODS
79 birds with avian mycobacteriosis (cases) and 316 nondiseased birds (controls) of similar age and taxonomic group that were present in the bird collection of the Zoological Society of San Diego from 1991 through 2005.


METHODS
Inventory and necropsy records from all eligible, exposed birds (n = 2,413) were examined to determine disease incidence and prevalence in the exposed cohort. Cases were matched in a 1:4 ratio to randomly selected controls of similar age and taxonomic grouping. Risk factors for mycobacteriosis (demographic, temporal, enclosure, and exposure characteristics as well as translocation history) were evaluated with univariate and multivariable conditional logistic regression analyses.


RESULTS
Disease prevalence and incidence were estimated at 3.5% and 8 cases/1,000 bird-years at risk, respectively. In the multivariable model, cases were more likely to have been imported into the collection, exposed to mycobacteriosis at a young age, exposed to the same bird species, and exposed in small enclosures than were controls. Odds for disease increased with an increasing amount of time spent with other disease-positive birds.


CONCLUSIONS
The low incidence of mycobacteriosis and the risk factors identified suggested that mycobacteria may not be easily transmitted through direct contact with infected enclosure mates. Identification of risk factors for avian mycobacteriosis will help guide future management of this disease in zoo bird populations.
Witte
Carmel L
CL
Wildlife Disease Laboratories, Zoological Society of San Diego, PO Box 120551, San Diego, CA 92112, USA. cwitte@sandiegozoo.org
Hungerford
Laura L
LL
Papendick
Rebecca
R
Stalis
Ilse H
IH
Rideout
Bruce A
BA
D000818:Animals; D000836:Animals, Zoo; D001715:Bird Diseases / Q000453:epidemiology / Q000473:pathology*; D001717:Birds; D002140:California / Q000453:epidemiology; D016022:Case-Control Studies; D015994:Incidence; D009164:Mycobacterium Infections / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors