Today's parasite is about as Aussie as they come - Trypanosoma irwini - a blood parasite named in honour of the late Steve "Crocodile Hunter" Irwin. What's more, this parasite infects an iconic Australian host, none other than the Koala (Phascolarctos cinereus). While the vector host for T. irwini is currently unknown, it is likely that this parasite features a life-cycle broadly similar to other trypanosomes we have featured on this blog - that is alternating sexual and asexual stages in a vector host and a vertebrate host. Trypanosoma irwini is by no mean the only unique Trypanosoma found in Australian. Scientists have been describing many novel species of Trypanosoma from the marsupials of Australia, and no doubt there are many, many more waiting to be discovered.
In addition to T. irwini, the Koala is also infected by two other species of Trypanosoma. While on its own, T. irwini seems to be pretty benign, if it gets mixed up with the other Trypanosoma species or other infections such as chlamydia or the retrovirus which causes koala AIDS syndrome, it can lead to disease in its host. Like many other parasites, the pathogenecity of T. irwini is not so straightforward, and may only manifest itself under certain conditions.
Photo from McInnes et al. (2009)
McInnes, L.M., Gillett, A., Ryan, U.M., Austen, J., Campbell, R.S.F., Hanger, J. and Reid, S.A. (2009) Tryapnosoma irwini n. sp. (Sarcomastigophora: Trypanosomatidae) from the koala (Phascolarctos cinereus). Parasitology 136: 875-885.
McInnes, L.M., Gillett, A.,Hanger, J., Reid, S.A. and Ryan, U.M. (2011) The potential impact of native Australian trypanosome infections on the health of koala (Phascolarctos cinereus). Parasitology 138: 873-883