EFFICACY OF TREATMENT AND LONG-TERM FOLLOW-UP OFBATRACHOCHYTRIUM DENDROBATIDISPCR-POSITIVE ANURANS FOLLOWING ITRACONAZOLE BATH TREATMENT

Abstract

All anuran specimens in the Wildlife Conservation Society's collections testing positive for Batrachochytrium dendrobatidis (Bd) were treated with itraconazole and then studied after treatment to assess the long-term effects of itraconazole and the drug's effectiveness in eliminating Bd carriers. Twenty-four individuals and eight colonies of 11 different species (75 total specimens) tested positive for Bd via polymerase chain reaction (PCR) on multicollection survey. All positive individuals and colonies were treated with a 0.01% itraconazole bath solution and retested for Bd via one of two PCR methodologies within 14 days of treatment completion, and all were negative for Bd. A total of 64 animals received secondary follow-up PCR testing at the time of death, 6-8 mo, or 12-15 mo post-treatment. Fourteen animals (14/64, 21.9%) were PCR positive for Bd on second follow-up. The highest percentage positive at second recheck were green-and-black poison dart frogs (Dendrobates auratus; 5/5 specimens, 100%), followed by red-eyed tree frogs (Agalychnis callidryas; 4/11, 36.4%), grey tree frogs (Hyla versicolor; 1/3, 33.3%), and green tree frogs (Hyla cinera; 3/11, 27.3%). Re-testing by PCR performed on 26/28 individuals that died during the study indicated 11/26 (42.3%) were positive (all via DNA extracted from formalin-fixed paraffin-embedded skin sections). However, there was no histologic evidence of chytridiomycosis in any of 27/28 individuals. The small number of deceased animals and effects of postmortem autolysis limited the ability to determine statistical trends in the pathology data, but none of the necropsied specimens showed evidence of itraconazole toxicity. Problems with itraconazole may be species dependent, and this report expands the list of species that can tolerate treatment. Although itraconazole is effective for clearance of most individuals infected with Bd, results of the study suggest that repeat itraconazole treatment and follow-up diagnostics may be required to ensure that subclinical infections are eliminated in amphibian collections.

Large-scale recovery of an endangered amphibian despite ongoing exposure to multiple stressors

“…To provide frogs for the experiment, adult R. sierrae were collected from each of three persistent populations (including two in Yosemite) and three Bd-naïve populations (Table S4). Frogs from the persistent populations were Bd-positive (Table S4) and therefore, cleared of infection using itraconazole (44). Naïve frogs were uninfected but treated with itraconazole concurrently to ensure that all frogs were treated similarly.…”

A first screening of chytrid fungus Batrachochytrium in amphibians in French zoos

“…It is known that animals involved in the international trade can be a reservoir for pathogens such as Bd (Spitzen‐van der Sluijs et al ., ; Kolby et al ., ; Winters et al ., ) and Bsal (Martel et al ., ; Cunningham et al ., ; Sabino‐Pinto et al ., ). With regard to the amphibians in zoos, to our knowledge the presence of Bd is only detected occasionally but no global studies have been carried out at the regional or national level (Jones et al ., ; Churgin et al ., ; Georoff et al ., ; Winters et al ., ). Even if only captive‐bred amphibians were considered, measures to prevent new pathogens entering infection‐free collections are essential.…”

PRESENCE AND PREVALENCE OFBATRACHOCHYTRIUM DENDROBATIDISIN COMMERCIAL AMPHIBIANS IN MEXICO CITY

“…Some studies made on anurans show that a treatment of itraconazole at different concentrations and different treatments reliably cures Bd infection, but there are also some reports of toxicity. 2,6,15,37 Evaluation of effectiveness of different treatments and antifungals need to be performed before treating the entire colony.…”