Research Article

Trypanosoma irwini n. sp (Sarcomastigophora: Trypanosomatidae) from the koala (Phascolarctos cinereus)

L. M. McINNESa1 c1, A. GILLETTa2, U. M. RYANa1, J. AUSTENa1, R. S. F. CAMPBELLa3, J. HANGERa2 and S. A. REIDa1

a1 Division of Health Sciences, School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, Perth 6150, Western Australia

a2 The Australian Wildlife Hospital, Beerwah, Queensland, Australia

a3 School of Veterinary Science, James Cook University, Townsville, Queensland 4811, Australia


The morphology and genetic characterization of a new species of trypanosome infecting koalas (Phascolarctos cinereus) are described. Morphological analysis of bloodstream forms and phylogenetic analysis at the 18S rDNA and gGAPDH loci demonstrated this trypanosome species to be genetically distinct and most similar to Trypanosoma bennetti, an avian trypanosome with a genetic distance of 0·9% at the 18S rDNA and 10·7% at the gGAPDH locus. The trypanosome was detected by 18S rDNA PCR in the blood samples of 26 out of 68 (38·2%) koalas studied. The aetiological role of trypanosomes in koala disease is currently poorly defined, although infection with these parasites has been associated with severe clinical signs in a number of koalas. Based on biological and genetic characterization data, this trypanosome species infecting koalas is proposed to be a new species Trypanosome irwini n. sp.

(Received January 27 2009)

(Revised March 18 2009)

(Accepted March 18 2009)