New research led by Murdoch University's School of Veterinary and Life Sciences suggests the catastrophic decline of the endangered woylie may be linked to common infections with Trypanosoma parasites.
Associated in humans to Chagas disease in South America and sleeping sickness in Africa, Trypanosoma species are found in a wide range of animals and vary in degree from non-pathogenic to highly pathogenic.
Findings from the newly published study challenge the long-held view that, while pervasive in Australian marsupials, trypanosomes have little impact on the animals' health.
"In testing 600 native marsupials, we found positive results in 67 per cent of live-trapped and released woylies and 60 per cent of those which had been killed by automobiles," said Murdoch PhD candidate Mrs Adriana Botero.
"Parasite species fell into three groups, or 'clades', with a marked difference in the composition of Trypanosoma infections between woylies who came from stable populations as opposed to those from declining populations.
"Ninety-six per cent of animals from the declining populations which tested positive were infected by a parasite species from Clade A, similar to Trypanosoma copemani, or had a mixed infection.
"On the other hand, woylies from stable populations who tested positive were infected by a parasite from Clade B, similar to Trypanosoma gilletti, which our group at Murdoch have named Trypanosoma vegrandis sp. nov.
"This suggests that trypanosomes from Clade A could be important contributors to the dramatic decline of the woylie."
Mrs Botero said woylies infected by the T. copemani-like parasite showed moderate to marked inflammation in tissues as well as evidence of damage to heart muscles.
She added that T. copemani had been reported in the blood of other endangered marsupials, including Gilbert's potoroos and quokkas from WA as well as koalas from Queensland.
Since 1999, woylie populations have undergone a dramatic 90 per cent reduction in abundance despite no apparent increase in the number or type of predators and no apparent decrease in natural resources.
Researchers have called for further studies to confirm their hypothesis and inform a new conservation strategy.
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"Trypanosomes genetic diversity, polyparasitism and the population decline of the critically endangered Australian marsupial, the brush tailed bettong or woylie (Bettongia penicillata)." Adriana Botero,Craig K. Thompson,Christopher S. Peacock,Peta L. Clode,Philip K. Nicholls,Adrian F. Wayne,Alan J. Lymbery,R.C. Andrew Thompson. International Journal for Parasitology: Parasites and Wildlife, December 2013. dx.doi.org/10.1016/j.ijppaw.2013.03.001