Confirmation of a unique species of Giardia, parasitic in the quenda (Isoodon obesulus)

The ‘quenda genotype’ of Giardia was first identified in quenda (syn. southern brown bandicoots, Isoodon obesulus) in Western Australia in 2004. We aimed to formally describe this genotype as a species of Giardia, Giardia peramelis. Seventy five faecal samples positive for G. peramelis were obtained from quenda within the Statistical Division of Perth, Western Australia. These samples were used in morphological and molecular characterisation of G. peramelis. PCR amplification and sequencing was most successful at the 18S rRNA and ITS1-5.8s-ITS2 loci. Phylogenetic analyses placed G. peramelis external to the ‘Giardia duodenalis species complex’ and Giardia microti. This confirmed the uniqueness of G. peramelis, warranting classification as a separate species of Giardia. Study findings suggest quenda are a natural host for G. peramelis.