Platypus mucormycosis and its conservation implications

Since 1982 some Tasmanian platypuses have been affected by a fungal disease called mucormycosis. This disease causes skin lesions, morbidity and mortality in these iconic Australian animals. Here we review the contemporary understanding of the epidemiology of mucormycosis and its potential impacts on the conservation status of platypuses. Mucor amphibiorum, the fungal pathogen responsible for mucormycosis, may have been transported to Tasmania with infected frogs from mainland Australia. Although there are no confirmed cases of mucormycosis from platypuses in mainland Australia, mucormycosis appears to have spread widely in Tasmania since 1982. In the 25 years to 2007, ulcerated platypuses were captured across 11 river catchments that cover 24% of the land area of Tasmania. The potential disease spread is much larger, with unconfirmed public observations over the same period reporting ulcerated platypuses in 11 additional catchments spanning another 31% of the state. Though a number of mechanisms are suggested, it is currently unclear what the route of individual infection is, or how mucormycosis is spread within or between catchments in Tasmania. There is currently insufficient fundamental information on the distribution and impacts of the disease to rigorously assess the threat. For instance, it is unclear whether mucormycosis has persisted in platypus populations that were historically affected, whether the proportion of infected animals has changed within these areas, or whether platypuses still persist and reproduce successfully in formerly infected areas. Difficulties in reliably quantifying platypus abundance compromise researchers’ ability to determine impacts on populations.