Action: Use antibacterial treatment to reduce chytridiomycosis infection
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- Two studies (including one randomized, replicated, controlled study) in New Zealand and Australia found that treatment with chloramphenicol antibiotic ointment (Bishop et al. 2009) or solution, with other interventions in some cases, cured green tree frogs and one Archey’s frog of chytridiomycosis.
- One replicated, controlled study found that treatment with trimethoprim-sulfadiazine increased survival time but did not cure blue-and-yellow poison dart frogs of chytridiomycosis.
Effective treatments for chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis, are vital to ensure the success of amphibian captive-breeding programmes. They are also required to reduce the risk of spreading the disease when animals are moved between breeding facilities, released or translocated between field sites.
Supporting evidence from individual studies
A replicated, controlled study in a laboratory (Nichols & Lamirande 2001) found that treatment of blue-and-yellow poison dart frogs Dendrobates tinctorius with trimethoprim-sulfadiazine survived longer but were not cured of the chytrid infection. Frogs treated with trimethoprim-sulfadiazine survived longer than untreated frogs. Juveniles were experimentally infected with the chytrid fungus Batrachochytrium dendrobatidis. Once excessive skin shedding had started, frogs were treated with trimethoprim-sulfadiazine (0.1% solution). Frogs were immersed in the treatment for five minutes each day for 11 consecutive days. Controls were untreated. Frogs were then killed humanely and examined.
A study in a laboratory in New Zealand (Bishop et al. 2009) found that treatment of one Archey’s frog Leiopelma archeyi with an antibiotic ointment cured it of chytridiomycosis. At the end of five days’ treatment with chloramphenicol ointment, the infection was significantly reduced (zoospore equivalents: 176–217 to 7). Over the following three months the frog tested negative for chytridiomycosis in five tests. Chloramphenicol treatment did not appear to have any effect on weight, behaviour or health. The frog had 5 mg of chloramphenicol ointment applied to its back for five days. Four other wild caught frogs had chloramphenicol in water (10 mg/L) added to their containers. Containers were disinfected with 70% ethanol and the treatment solution changed daily for five days. They were tested for the chytrid fungus on arrival, at 2, 4, 8, 14 and 19 weeks and at the end of the trial. Behaviour, food consumption and weight gain was monitored daily.
A randomized, replicated, controlled study in 2011 in Queensland, Australia (Young et al. 2012) found that treatment of captive green tree frogs Litora caerulea with chloramphenicol solution cured terminal and pre-symptom chytridiomycosis infections. The three terminally infected frogs also received electrolyte fluids and increased ambient temperature from 22 to 28°C. All 18 infected frogs bathed in chloramphenicol solution were clinically normal within 4–5 days and cured by day 13–17. All five terminally infected frogs that did not receive treatment died within 24–48 hours. Treated controls remained uninfected and clinically normal. Frogs were collected from the wild and randomly assigned to treatments. Seventeen frogs experimentally infected with chytridiomycosis and one naturally infected frog received treatment and five infected (one naturally) were controls. Eighteen uninfected frogs were also treated. Treatment was continuous immersion in 20 mg/L chloramphenicol solution for 14 (n = 3) or 28 (n= 15) days. Solutions were changed daily. Three terminally infected frogs also received electrolyte fluids under the skin every eight hours for six days and increased ambient temperature (from 22 to 28°C). Frogs were swabbed for testing every seven days for 34 days and at 102 days.
- Nichols D.K. & Lamirande E.W. (2001) Successful treatment of chytridiomycosis. Froglog, 46, 1
- Bishop P.J., Speare R., Poulter R., Butler M., Speare B.J., Hyatt A., Olsen V. & Haigh A. (2009) Elimination of the amphibian chytrid fungus Batrachochytrium dendrobatidis by Archey's frog Leiopelma archeyi. Diseases of Aquatic Organisms, 84, 9-15
- Young S., Speare R., Berger L. & Skerratt L.F. (2012) Chloramphenicol with fluid and electrolyte therapy cures terminally ill green tree frogs (Litoria caerulea) with chytridiomycosis. Journal of Zoo and Wildlife Medicine, 43, 330-337