Description of Three New Species ofTheileriaBettencourt, Franca & Borges, 1907 From Macropodoidea in Western Australia

Sequence analyses at mitochondrial and nuclear loci reveal a novel Theileria sp. and aid in the phylogenetic resolution of piroplasms from Australian marsupials and ticks

The order Piroplasmida encompasses two main families: Babesiidae and Theileriidae, containing tick-borne pathogens of veterinary and medical importance worldwide. While only three genera (Babesia, Cytauxzoon and Theileria) comprising piroplasm parasites are currently recognised, phylogenetic studies at the 18S rRNA (18S) gene suggest that these organisms represent at least ten lineages, one of which comprises the relatively unique and highly diverse Theileria spp. from Australian marsupials and ticks. As an alternative to analysing 18S sequences alone, sequencing of mitochondrial genes has proven to be useful for the elucidation of evolutionary relationships amongst some groups of piroplasms. This research aimed to characterise piroplasms from Australian native mammals and ticks using multiple genetic markers (18S, cytochrome c, oxidase subunit III (cox3) and cytochrome B (cytB)) and microscopy. For this, nearly complete piroplasm-18S sequences were obtained from 32 animals belonging to six marsupial species: eastern bettong (Bettongia gaimardi), eastern quoll (Dasyurus viverrinus), eastern grey kangaroo (Macropus giganteus), swamp wallaby (Wallabia bicolor), quokka (Setonix brachyurus) and Gilbert’s potoroo (Potorous gilbertii). The organisms detected represented eight novel Theileria genotypes, which formed five sub-clades within the main marsupial clade containing previously reported Australian marsupial and tick-derived Theileria spp. A selection of both novel and previously described Australian piroplasms at the 18S were also successfully characterised, for the first time, at the cox3 and cytB loci, and corroborated the position of Australian native theilerias in a separate, well-supported clade. Analyses of the cox3 and cytB genes also aided in the taxonomic resolution within the clade of Australian Piroplasmida. Importantly, microscopy and molecular analysis at multiple loci led to the discovery of a unique piroplasm species that clustered with the Australian marsupial theilerias, for which we propose the name Theileria lupei n. sp.

Wildlife parasitology in Australia: past, present and future

Wildlife parasitology is a highly diverse area of research encompassing many fields including taxonomy, ecology, pathology and epidemiology, and with participants from extremely disparate scientific fields. In addition, the organisms studied are highly dissimilar, ranging from platyhelminths, nematodes and acanthocephalans to insects, arachnids, crustaceans and protists. This review of the parasites of wildlife in Australia highlights the advances made to date, focussing on the work, interests and major findings of researchers over the years and identifies current significant gaps that exist in our understanding. The review is divided into three sections covering protist, helminth and arthropod parasites. The challenge to document the diversity of parasites in Australia continues at a traditional level but the advent of molecular methods has heightened the significance of this issue. Modern methods are providing an avenue for major advances in documenting and restructuring the phylogeny of protistan parasites in particular, while facilitating the recognition of species complexes in helminth taxa previously defined by traditional morphological methods. The life cycles, ecology and general biology of most parasites of wildlife in Australia are extremely poorly understood. While the phylogenetic origins of the Australian vertebrate fauna are complex, so too are the likely origins of their parasites, which do not necessarily mirror those of their hosts. This aspect of parasite evolution is a continuing area for research in the case of helminths, but remains to be addressed for many other parasitic groups.

Molecular detection and characterisation of Babesia and Theileria in Australian hard ticks

Babesia and Theileria are intraerythrocytic protozoans of the phylum Apicomplexa. These species are capable of infecting wild and domestic animals and have historically caused great economic loss in the agricultural industry. In recent years human babesiosis has been deemed an emerging zoonosis in North America, Europe and Asia. The first locally acquired case of babesiosis in Australia, caused by Babesia microti, was reported in March 2012. A number of native Babesia and Theileria species have been identified in Australian marsupials, however their associated tick vectors and threat to human health is unknown. In the present study DNA was extracted from 1154 ticks collected from across Australia. PCR was used to amplify a Babesia and Theileria-specific partial region of the 18S ribosomal RNA gene. Positive samples were sequenced and phylogenetic analysis was performed. Twenty-nine sequences were obtained from ticks belonging to the genera Ixodes, Haemaphysalis and Bothriocroton. The sequences were closely related to Babesia macropus, and Theileria recently identified in marsupials and monotremes. Bayesian inference and maximum likelihood methods showed that Australian Babesia and Theileria species form monophyletic groups.

A high prevalence of Theileria penicillata in woylies (Bettongia penicillata)

The woylie or brush-tailed bettong (Bettongia penicillata) is a medium-sized native Australian marsupial that has undergone a dramatic decline in numbers in recent years. Trypanosome parasites have been identified in the woylie but little is known about the prevalence and clinical impact of other haemoprotozoan parasites in these marsupials. In the present study, the occurrence and molecular phylogeny of a piroplasm was studied in woylies from six different sites in Western Australia (WA). Blood samples were screened by PCR at the 18S rRNA locus and 80.4% (123/153) of the blood samples were positive for piroplasm DNA. Sequence and phylogenetic analysis of 12 of these positives identified them as Theileria penicillata, and sequencing of cloned PCR products indicated that no other species of Theileria were present. Infected woylies had a lower body weight but microscopic evaluation of the blood films indicated that T. penicillata did not appear to cause red cell injury or anaemia. Further studies are required to determine the clinical significance of T. penicillata in woylies.