Amphibian Disease Laboratory, Wildlife Disease Laboratories, San Diego Zoo’s Institute for Conservation Research, San Diego, CA, USA
The detection and control of emerging infectious diseases such as chytridiomycosis are key considerations for facilities with captive amphibians. This study uses a large diagnostic testing database to describe the occurrence of Batrachochytrium dendrobatidis (Bd) in captive amphibians and to examine testing and treatment strategies. From February 2009 to March 2010, 4400 skin swabs from 67 submitting institutions were processed for real-time PCR testing for Bd.1 Information gathered for each sample included species, clinical signs, reason for testing, and treatments used. Of samples from seven partner institutions in which the entire amphibian collection was screened, the percent Bd-positive ranged from 0.0% to 4.6%. When samples were grouped by testing category, the percent Bd-positive was highest for quarantine screening and in cases of exposure to infected animals, and lowest in surveillance of apparently healthy collection animals. As noted previously,1 multiple samples were sometimes needed to detect all animals with low-level (subclinical) Bd infection; this has implications for quarantine testing. The most common treatment for Bd-infected animals was a 0.01% itraconazole bath;2 however, lower doses were also effective. Clearance of Bd infection following treatment was verified by serial PCR testing. Treatment failures were rare, and causes included re-exposure to Bd due to inadequate disinfection. An experimental assay compared PCR results from different commercially available swab types inoculated with known quantities of Bd zoospores. Wood-handled cotton swabs had poor test performance when compared to rayon-tipped swabs. These findings highlight the importance of appropriate biosecurity and testing protocols to reduce the threats of infectious diseases in captive survival assurance colonies.
This work was funded by National Leadership Grant LG-25-08-0066 from the Institute of Museum and Library Services. Any views, findings, conclusions or recommendations expressed in this publication do not necessarily represent those of the Institute of Museum and Library Services. The authors gratefully acknowledge the following institutions and facilities for providing samples and other information included in this study: Atlanta Botanical Garden, Detroit Zoo, Fort Worth Zoo, National Aquarium Baltimore, Omaha’s Henry Doorly Zoo, San Diego Zoo, Zoo Atlanta, Adventure Aquarium, American Museum of Natural History, Arizona Exotic Animal Hospital, Buffalo Zoo, Calgary Zoo, Cape May County Zoo, Central Florida Zoo & Botanical Gardens, City of Austin, TX, Como Zoo, Ecomuseum Zoo, Ellen Trout Zoo, Fresno Chaffee Zoo, Gladys Porter Zoo, Great Plains Zoo, Jenkinson's Aquarium , John Ball Zoological Garden, Liberty Science Center, Maritime Aquarium, Maryland Zoo in Baltimore, Memphis Zoo, Milwaukee County Zoo, Minnesota Zoo, Monterey Bay Aquarium, Nashville Zoo, National Mississippi River Museum & Aquarium, New England Aquarium, North Carolina Aquarium Roanoke Island, North Carolina Zoo, Oakland Zoo, Oklahoma City Zoo, Orlando Science Center, Palm Beach Zoo, Phoenix Zoo, Point Defiance Zoo and Aquarium, Racine Zoo, Red Buttes Environmental Biology Laboratory (US Fish and Wildlife Service), Reid Park Zoo, Roger Williams Park Zoo, Rolling Hills Wildlife Adventure, Roosevelt Park Zoo, Sacramento Zoo, San Antonio Zoo, Saratoga National Fish Hatchery (US Fish and Wildlife Service), Sea World Florida, Sedgwick County Zoo, Smithsonian National Zoo, St. Louis Zoo, The Wilds, Toledo Zoo, Turtle Back Zoo, United States Geological Survey BRD, United States Geological Survey San Diego Field Station, Virginia Aquarium, Wildlife Conservation Society (Bronx Zoo, Central Park Zoo, New York Aquarium, Prospect Park Zoo), and Zoo Montana.
1. Hyatt, A.D., D.G. Boyle, V. Olsen, D.B. Boyle, L. Berger, D. Obendorf, A. Dalton, K. Kriger, M. Hero, H. Hines, R. Phillott, R. Campbell, G. Marantelli, F. Gleason and A. Colling. 2007. Diagnostic assays and sampling protocols for the detection of Batrachochytrium dendrobatidis. Dis Aquatic Organ. 73:175–192.
2. Pessier, A.P. 2008. Management of disease as a threat to amphibian conservation. International Zoo Yearbook. 42:30–39.