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Individual study: Treatment of amphibians infected with chytrid fungus: learning from failed treatments with itraconazole, antimicrobial peptides, bacteria, and heat therapy

Published source details

Woodhams D.C., Geiger C.C., Reinert L.K., Rollins-Smith L.A., Lam B., Harris R.N., Briggs C.J., Vredenburg V.T. & Voyles J. (2012) Treatment of amphibians infected with chytrid fungus: learning from failed treatments with itraconazole, antimicrobial peptides, bacteria, and heat therapy. Diseases of Aquatic Organisms, 98, 11-25


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Use temperature treatment to reduce chytridiomycosis infection Amphibian Conservation

A small, replicated, controlled study in 2007 of captive amphibians (Woodhams et al. 2012) found that short-term heat treatment at 30–35°C did not cure northern leopard frogs Lithobates pipiens of chytridiomicosis. None of the four infected frogs treated were cured of their infection. Five of six uninfected frogs remained uninfected during treatment, but all control frogs kept in group enclosures were infected by the end of the experiment. Naturally infected frogs were placed in an incubator at 30°C overnight and then 35°C for 24 hours. Control groups of 3–4 frogs were kept at room temperature (23°C).

 

Use antifungal skin bacteria or peptides to reduce chytridiomycosis infection Amphibian Conservation

A randomized, replicated, controlled study in 2007 in a laboratory in Virginia, USA (Woodhams et al. 2012) found that survival of mountain yellow-legged frogs Rana muscosa naturally infected with chytridiomycosis was not increased by adding chytrid-inhibiting skin bacteria. Survival of frogs treated with bacteria was 50% compared to 39% for infected controls. Infection was not cleared in surviving frogs. However, weight loss was reduced with treatment (0.1 vs 0.4 g/week). Wild-caught frogs were randomly assigned to treatments. Twenty were bathed in water containing bacteria (Pedobacter cryoconitis) isolated from mountain yellow-legged frog and 13 control frogs in water alone for two hours. Frogs were swabbed and tested at seven and 13 days after treatment.

A randomized, replicated, controlled study in 2010 in a laboratory in Switzerland (Woodhams, Geiger, Reinert, Rollins-Smith, Lam, Harris, Briggs, Vredenburg & Voyles 2012) found that survival of common toad Bufo bufo toadlets was not significantly increased by treatment with antimicrobial skin peptides before or after infection with chytridiomycosis, although treatment may have cured infection in some individuals. Survival of toads treated with peptides immediately before or eight days after infection was not significantly different from chytrid infected controls (12 vs 18%). However, none of the three treated toadlets that survived to 35 days were infected with chytridiomycosis, compared to all three of the untreated infected controls. Peptide treatment alone did not reduce survival compared to uninfected controls (64% vs 58%). Captive toadlets were randomly assigned to treatments. Seventeen were infected with chytridiomycosis alone. Seventeen were treated with skin peptides from edible frogsPelophylax esculentus (2 minute bath in 400 μg/ml peptide solution) immediately before infection and 17 on day eight following infection. Twenty four were uninfected controls, 12 of which were bathed with peptides. Swabs were taken and tested for the chytrid fungus on day 35.

 

Use antifungal treatment to reduce chytridiomycosis infection Amphibian Conservation

Randomized, replicated, controlled studies in 2007–2009 of amphibians with chytridiomycosis in the USA and Tasmania (Woodhams et al. 2012) found that treatment with itraconazole cured northern leopard frogs Lithobates pipiens, did not increase survival of mountain yellow-legged frogs Rana muscosa and was highly toxic to striped marsh frog Limnodynastes peronii metamorphs. All four treated leopard frogs were cured, although one control frog died with signs of toxicity. Eight treated marsh frogs died by the third day of treatment. Although treatment did not increase survival of yellow-legged frogs (treated: 30%; controls: 39%), it reduced weight loss (0.2 vs 0.4 g/week) and cleared infection in surviving frogs. Frogs were randomly assigned to treatments. Ten wild-caught naturally infected yellow-legged frogs, four infected leopard frogs and eight wild-caught naturally infected marsh frogs were bathed with itraconazole (100 mg/L) for 5 minutes daily and then rinsed for 11, five or three days respectively. There were 13 control yellow-legged frogs, seven marsh frogs (bathed in water) and eight leopard frogs. Yellow-legged frogs were tested for infection at seven and 13 days after treatment and leopard frogs before and 17 days after treatment.

 

Use antifungal treatment to reduce chytridiomycosis infection Amphibian Conservation

A randomized, replicated, controlled study in 2010 in Switzerland (Woodhams et al. 2012) found that common midwife toad Alytes obstetricans tadpoles treated with three commercial antifungal treatments were not cured of chytridiomicosis. All but one tadpole treated with PIP Pond Plus and all those treated with Steriplant N remained infected. Only three of 18 treated with Mandipropamid (at 0.1, 1.4 and 1.6 mg/L) were cured. Wild-caught tadpoles were randomly assigned to treatments. Twenty-eight were treated daily with PIP Pond Plus (probiotic bacteria, enzymes and isopropanol) in doses of 0, 25, 50 or 100 μg/ml added to their water for seven days. Twenty-eight were treated with Steriplant N (water and 0.04% oxidants) on day 0 (control), one (5 parts per million), two (10 parts per million) or three (15 parts per million). Twenty-one tadpoles were treated with Mandipropamid (phenylglycinamides and mandelamides) at 18 different doses from 0.01 to 4 mg/L (in acetone), with three controls. Tadpoles were swabbed and tested a week after treatment.