Getting the jump on disease!!

May 2001

Disease and Declining Frog Australia converged to consider Populations Disease Conference 2000 options for effective control and man- There is no doubt that generate In order to address this particular agement, and to devise strategies to intense interest in the Wet Tropics. issue, the Rainforest CRC organised minimise the risks of disease on wild While residents and visitors to the an International Conference in Cairns at global, national, region gain great enjoyment from in August 2000. A Workshop which regional and local community levels. living in such close proximity to these followed was designed to develop Delegates included policy-makers, delightful creatures, researchers, strategies to lessen the impacts of laboratory and field scientists, conservationists, veterinarians and known and emerging pathogens on veterinarians, commercial frog aqua- micro-biologists grow increasingly wild amphibian populations. Special- culturalists,micro-biologists,repre- concerned for their immediate and ists from the U.K., U.S.A., Spain, New sentatives from frog interest groups, long-term future. Zealand, Germany, Uruguay, and horticultural industries and the general public. The objectives of the Such groups are acutely aware that conference were to: amphibian populations have been • assemble experts with the most steadily declining for more than a current information on amphibian decade. Many species are now endan- pathogens and their effects, and gered, and some have disappeared • promote and improve net- completely. This disturbing trend working, information flow and applies not only in the Wet Tropics, but exchange of ideas among people is occurring on a global scale. working on and with amphibian disease. A number of theories have been put forward to explain the phenomenon, The aim of the Workshop was to including: habitat destruction, acid develop a set of recommendations for rain, fertilisers and pesticides, global government bodies, non-government warming and ozone depletion, the organisations and individuals, which introduction of exotic predators and outlined actions that would lessen the disease. It is clear however, that no one risks of disease to wild amphibian single causal factor can be isolated. populations.

In a bioregion like the Wet Tropics, Which diseases cause the greatest where humans and amphibians live in concern? relatively close proximity and there is Infectious diseases capable of causing a high level of biodiversity among declines of wild amphibians: frogs, disease and the spread of • are highly virulent infection among frog populations is a Top: Great with Chytrids • affect more than one species prime concern. Centre: Red-eyed Green Tree Frog • affect the adult form only with a deformed eye • are associated with water, and Bottom: Green Tree Frog with Chytrids • persist once frogs have disap- Photographs: Lee Berger peared either in another host or in the environment itself. During the Conference, two infectious RANAVIRUSES Within the Draft Recommendations agents fitting this profile were identi- Ranaviral disease in amphibians is proposals have been written to address fied as being of greatest concern in caused by multiple species of closely the following issues: relation to wild frog populations, related viruses of the Ranavirus genus. • Movement of amphibians in farm particularly in Australia. These agents Some Ranaviral species can infect am- produce - reduction at source and were the Chytridi fungus and phibians, reptiles and fish, but as yet management at receiving end Ranaviruses. there have been no documented epi- • Movement of amphibians in other demics in Australia. More obvious materials like soil and water CHYTRIDIOMYCOSIS symptoms of raniviral disease in • Dealing with pathogens in the (The Frog Chytrid) amphibians include: laboratory This disease is caused by the fungus • Decreasing the risk of disease in Batrachochytrium dendrobatidus and is Tadpoles: decreased activity, pinprick amphibian husbandry widespread in Australian frogs, cane bleeding (focal haemorrhages), bloat • Reducing the spread of infection toads and axolotyls. The spores of the (ascites) and death during field research fungus grow inside the outer layers of Metamorphs: decreased activity, fluid skin, resulting in a thickening of the buildup under the skin (anasarca), bloat Community involvement imperative epidermis and keratin. This pathogen (ascites) pinprick bleeding (focal haem- The draft includes several suggestions is capable of causing high incidence of orrhages) and death that are designed to make the most of sickness and death in captive Adults: decreased activity, ulcerations community interest and involvement, populations, and spores of the fungus of the skin, pinprick bleeding (focal and to encourage and assist further are transmitted via water. haemorrhages) and death. community participation in:

Obvious symptoms include: Strategies emerging from Workshop • Disease surveillance - monitoring Strategies which the Workshop iden- mortality levels, and collecting • Abnormal posture - hind legs held tified to lessen the risks and control the road kill samples out from flanks, does not impacts of disease included: • Caring and nurturing - rehabilita- right itself tion of frogs, repatriation, hus- • Abnormal behaviour - nocturnal • Prevention of import of infected bandry in daylight, animal fails to animals into disease free areas • Population monitoring - densities, flee or has seizure when handled • Limiting movement of all frogs movements, reproductive activity • Thickened epidermis, ulcerations between contaminated areas and success on the skin and body swelling • Implement protocols on handling • Maintaining healthy amphibian • Death wild amphibians habitats - protection, creation, en- • Maintaining healthy frog vironmentally friendly practices, Tadpoles do not display these symp- environments surveillance for exotic amphibians toms, but carry the disease in their • Collection and preservation of • Education - schools, public events mouths when, during metamorphsis, genetic material and venues the spores become redistributed to the • Support - moral, financial and skin of the body. This aspect is a great political contributor to the spread of the The complete draft recommendations • Promotion - media and other disease. are available on the web at: conservation groups www.jcu.edu.au/school/phtm/ PHTM/frogs/adrec.htm