Jill Austen

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

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.

Morphological and molecular characterization of Trypanosoma copemani n. sp. (Trypanosomatidae) isolated from Gilbert's potoroo (Potorous gilbertii) and quokka (Setonix brachyurus).

Little is known of the prevalence and life-cycle of trypanosomes in mammals native to Australia. Native Australian trypanosomes have previously been identified in marsupials in the eastern states of Australia, with one recent report in brush-tailed bettongs (Bettongia penicillata), or woylie in Western Australia in 2008. This study reports a novel Trypanosoma sp. identified in blood smears, from 7 critically endangered Gilberts potoroos (Potorous gilbertii) and 3 quokkas (Setonix brachyurus) in Western Australia. Trypanosomes were successfully cultured in vitro and showed morphological characteristics similar to members of the subgenus Herpetosoma. Phylogenetic analysis of 18S rRNA gene sequences identified 2 different novel genotypes A and B that are closely related to trypanosomes previously isolated from a common wombat (Vombatus ursinus) in Victoria, Australia. The new species is proposed to be named Trypanosoma copemani n. sp.

Cryptosporidium homai n. sp. (Apicomplexa: Cryptosporidiiae) from the guinea pig ( Cavia porcellus )

The morphological, biological, and molecular characterisation of a new Cryptosporidium species from the guinea pig (Cavia porcellus) are described, and the species name Cryptosporidium homai n. sp. is proposed. Histological analysis conducted on a post-mortem sample from a guinea pig euthanised due to respiratory distress, identified developmental stages of C. homai n. sp. (trophozoites and meronts) along the intestinal epithelium. Molecular analysis at 18S rRNA (18S), actin and hsp70 loci was then conducted on faeces from an additional 7 guinea pigs positive for C. homai n. sp. At the 18S, actin and hsp70 loci, C. homai n. sp. exhibited genetic distances ranging from 3.1% to 14.3%, 14.4% to 24.5%, and 6.6% to 20.9% from other Cryptosporidium spp., respectively. At the 18S locus, C. homai n. sp. shared 99.1% similarity with a previously described Cryptosporidium genotype in guinea pigs from Brazil and it is likely that they are the same species, however this cannot be confirmed as actin and hsp70 sequences from the Brazilian guinea pig genotype are not available. Phylogenetic analysis of concatenated 18S, actin and hsp70 sequences showed that C. homai n. sp. exhibited 9.1% to 17.3% genetic distance from all other Cryptosporidium spp. This clearly supports the validity of C. homai n. sp. as a separate species.

High prevalence of Trypanosoma vegrandis in bats from Western Australia

Abstract The present study describes the first report of Trypanosoma vegrandis in bats using morphology and sequence analysis of the 18S rRNA gene. The PCR prevalence of T. vegrandis in bats was 81.8% (18/22). The high prevalence of T. vegrandis in the present study suggests that bats may play an important role in the epidemiology of T. vegrandis in Australia. T. vegrandis appears to be geographically dispersed, has a wide distribution in Australia and low levels of host specificity.

HEALTH ASSESSMENT OF THE CHRISTMAS ISLAND FLYING FOX (PTEROPUS MELANOTUS NATALIS)

Abstract During July–August 2010, 28 Christmas Island flying foxes (Pteropus melanotus natalis) were captured and anesthetized for examination, sample collection, and release to determine the potential role of disease in recent population declines. Measurements and samples were taken for morphologic, hematologic, biochemical, and parasitologic analysis. These are the first blood reference ranges reported for this species. These data are being used to inform investigations into conservation status and population management strategies for the Christmas Island flying fox.

Further characterisation of two Eimeria species (Eimeria quokka and Eimeria setonicis) in quokkas (Setonix brachyurus)

The identification and characterisation of novel Eimeria species has largely been based on sporulated oocyst and sporocyst morphology, the host species and the geographical range. Variation in the size and shape of Eimeria oocysts across their host range however, make the identification and characterisation of novel species using traditional methodologies alone problematic. The use of molecular markers and phylogenetic analysis has greatly advanced our ability to characterise Eimeria species and has recently been applied to understand evolutionary relationships among Eimeria species from Australian marsupials. In the present study, Eimeria species isolated from quokkas (Setonix brachyurus) captured from Two Peoples Bay, Bald Island and Rottnest Island, Western Australia, were morphologically identified as Eimeria quokka and Eimeria setonicis. Both Eimeria species were identified as being polymorphic in nature with regards to sporulated oocyst and sporocyst morphometrics. Phylogenetic analysis using 18S rRNA and COI (cytochrome c oxidase subunit 1) genes, grouped E. quokka and E. setonicis within the Eimeria marsupial clade together with Eimeria trichosuri from brushtail possums, Eimeria macropodis from tammar wallabies (Macropus eugenii) and several unidentified macropod Eimeria species from western grey kangaroos (Macropus fuliginosus). This study is the first to characterise E. quokka and E. setonicis by molecular analysis, enabling more extensive resolution of evolutionary relationships among marsupial-derived Eimeria species.

Investigation of the morphological diversity of the potentially zoonotic Trypanosoma copemani in quokkas and Gilbert's potoroos

Trypanosomes are blood-borne parasites that can cause severe disease in both humans and animals, yet little is known of the pathogenicity and life-cycles of trypanosomes in native Australian mammals. Trypanosoma copemani is known to be infective to a variety of Australian marsupials and has recently been shown to be potentially zoonotic as it is resistant to normal human serum. In the present study, in vivo and in vitro examination of blood and cultures from Australian marsupials was conducted using light microscopy, immunofluorescence, scanning electron microscopy and fluorescence in situ hybridization. Promastigote, sphaeromastigote and amastigote life-cycle stages were detected in vivo and in vitro. Novel trypanosome-like stages were also detected both in vivo and in vitro representing an oval stage, an extremely thin stage, an adherent stage and a tiny round stage. The tiny round and adherent stages appeared to adhere to erythrocytes causing potential haematological damage with clinical effects similar to haemolytic anaemia. The present study shows for the first time that trypomastigotes are not the only life-cycle stages circulating within the blood stream of trypanosome infected Australian native marsupials and provides insights into possible pathogenic mechanisms of this potentially zoonotic trypanosome species.

The innate resistance of Trypanosoma copemani to human serum

Trypanosoma copemani is known to be infective to a variety of Australian marsupials. Characterisation of this parasite revealed the presence of stercorarian-like life-cycle stages in culture, which are similar to T. rangeli and T. cruzi. The blood incubation infectivity test (BIIT) was adapted and used to determine if T. copemani, like T. cruzi and T. rangeli, has the potential to grow in the presence of human serum. To eliminate any effects of anticoagulants on the complement system and on human high density lipoprotein (HDL), only fresh whole human blood was used. Trypanosoma copemani was observed by microscopy in all human blood cultures from day 5 to day 19 post inoculation (PI). The mechanism for normal human serum (NHS) resistance in T. copemani is not known. The results of this study show that at least one native Australian trypanosome species may have the potential to be infective for humans.

Molecular characterization of native Australian trypanosomes in quokka (Setonix brachyurus) populations from Western Australia

The quokka, Setonix brachyurus, is a vulnerable, small marsupial endemic to Western Australia. Blood samples were collected from quokkas from three different geographical locations; Two Peoples Bay, Bald Island and Rottnest Island. The overall prevalence of trypanosomes by nested PCR at the 18S ribosomal RNA gene was 57.3% (63/110) with prevalences of 91.4%, 85.3% and 4.9% respectively for Two Peoples Bay, Bald Island and Rottnest Island. Phylogenetic analysis conducted on 47 18S PCR positives identified two Trypanosoma copemani genotypes, with T. copemani genotype B, the most prevalent genotype infecting quokka populations from the three locations with an overall prevalence of 51.8% (24/47) compared to 34% for T. copemani genotype A (16/47). The overall prevalence of mixed T. copemani genotype A and B infections was 14.9% (7/47). Phylogenetic analysis of 26 quokka isolates at the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) locus, largely supported the 18S analysis but identified a mixed infection in one quokka isolate (Q4112-4117 from Two Peoples Bay). T. copemani genotype B has previously only been isolated from quokkas and the Gilberts potoroo whereas T. copemani genotype A has a wide host range and may be pathogenic. Further work is required to determine the clinical impact of T. copemani on marsupial populations.