Trypanosomes in a declining species of threatened Australian marsupial, the brush-tailed bettongBettongia penicillata(Marsupialia: Potoroidae)

Abstract

The brush-tailed bettong (Bettongia penicillata), or woylie, is a medium-sized macropod marsupial that has undergone a rapid and substantial decline throughout its home range in the Upper Warren region of Western Australia over a period of approximately 5 years. As part of an investigation into possible causes of the decline a morphologically distinct Trypanosoma sp. was discovered by light microscopy in the declining population but was absent in a stable population within the Karakamia Wildlife Sanctuary. Further investigations employing molecular methods targeting variations in the 18s rRNA gene determined that the trypanosome was novel and was also present within the Karakamia population albeit at a much lower overall prevalence and individual parasitaemia levels. Phylogenetic analysis suggests the novel Trypanosoma sp. to be closely related to other trypanosomes isolated from native Australian wildlife species. Although it appears unlikely that the parasite is solely responsible for the decline in woylie population size, it may (singularly or in conjunction with other infectious agents) predispose woylies to increased mortality.

First report of Trypanosoma vegrandis in koalas (Phascolarctos cinereus)

“…The PCR prevalence of T. vegrandis in koalas (13.6%) reported in the present study was at the lower end of prevalence estimates of T. vegrandis previously reported in woylies (14% -46%) [5,[15][16] and various other marsupial (up to 32%) [5] and bat species (88.9%)…”

“…Of the eight native trypanosomes formerly described, only T. copemani and T. vegrandis species have been identified in multiple hosts, with the chronic effects of T. copemani infections possibly linked with the decline of woylie populations [5,16]. The current findings add more evidence to the fact that trypanosomes in Australian marsupials comprise a heterogeneous community, with low levels of host specificity and no evidence of restricted geographical distribution [1,4,5,[14][15][16][17].…”

Novel trypanosomeTrypanosoma gillettisp. (Euglenozoa: Trypanosomatidae) and the extension of the host range ofTrypanosoma copemanito include the koala (Phascolarctos cinereus)

“…TRY1, TRY2, WYA1 and WYA2) (Smith et al 2008;Averis et al 2009) were also analysed. The analysis was only based on a short region (*480 bp) of 18S rDNA sequence because only small 18S rDNA fragments are presently available from GenBank for the chuditch and woylie derived trypanosome isolates.…”

Morphological and molecular characterization ofTrypanosoma copemanin. sp. (Trypanosomatidae) isolated from Gilbert's potoroo (Potorous gilbertii) and quokka (Setonix brachyurus)

“…More recently novel Trypanosoma spp. have been identified from the southern brown bandicoot (Isoodon obesulus) (Bettiol et al 1998), the eastern grey kangaroo (Macropus giganteus), common wombat (Vombatus ursinus) (Noyes et al 1999(Noyes et al , 2000, swamp wallaby (Wallabia bicolor) (Hamilton et al 2004), chuditch (Dasyrus geoffroiii) and brush-tailed bettongs (Bettongia penicillata), or woylies in Western Australia (Smith et al 2008).…”