ĭiagnosis of trypanosome infection largely relies on microscopy and a variety of molecular techniques. Despite this, there are clear gaps in sampling, and it is likely that trypanosomes are widespread across the Australian continent and in mammalian species. are present in animals sampled on the east and west coasts of Australia, as well as Tasmania. In addition, the monitoring of Australian mammals has shown that Trypanosoma spp. noyesi) in koalas, with similar results in woylies and the southern brown bandicoot. For example, surveillance in marsupials recorded up to five species ( T. Multiple trypanosome species have been documented in Australian wildlife. However, because incidental infection during feeding is not necessarily associated with vector competence, further research is needed to determine the role of these hematophagous invertebrates in trypanosome transmission. Other invertebrates such as lice, culicid mosquitoes, sand-flies, and tabanid flies are also believed to be potential trypanosome vectors. For example, in Australia, trypanosomes have been found in both aquatic leeches and ticks. Moreover, trypanosomes have been detected in hematophagous invertebrates that become infected while feeding on infected vertebrate hosts and which may act as parasite vectors. However, trypanosome infection has also been detected in other Australian vertebrate wildlife such as amphibians, birds, fish and reptiles. Marsupials, in particular, have been widely screened, allowing the identification of several trypanosome species (e.g. bats, marsupials, monotremes, and rodents). To date, most trypanosome surveillance has been directed toward screening Australian mammals (i.e. It is likely that a similar phenomenon extends to other marsupial species, highlighting the need for continued surveillance. vegrandis have been associated with population declines of woylies ( Bettongia penicillata) in Western Australia (WA). For instance, the native trypanosomes Trypanosoma copemani and T. While some Trypanosoma species are associated with serious disease, others play an undetermined role in the health of their hosts.
This includes more than 15 species of exotic and endemic trypanosomes as well as several unclassified species. Endemic Australian fauna is a susceptible target for trypanosome infection, and several studies have revealed a remarkable diversity of trypanosomes in Australian wildlife. Trypanosomes are haemoprotozoan parasites that infect a wide range of animal taxa. We demonstrated that RNA sequencing is sufficiently sensitive to detect low numbers of Trypanosoma transcripts and from diverse hosts and tissues types, thereby representing an effective means to detect trypanosomes that are divergent in genome sequence. To our knowledge, this is the first meta-transcriptomic analysis of trypanosomes in native Australian wildlife, expanding the known genetic diversity of these important parasites. In contrast, we provide the first evidence for a trypanosome in the eastern dwarf tree frog that was phylogenetically distinct from those described in other amphibians.
Phylogenetic analysis indicated that the trypanosomes infecting marsupials were related to those previously detected in placental and marsupial mammals, while the trypanosome in the regent honeyeater grouped with avian trypanosomes. We detected trypanosome sequences in all six species of vertebrates sampled, with positive samples in multiple organs and tissues confirmed by PCR. The evolutionary relationships among the trypanosomatid sequences identified were determined through phylogenetic analysis of 18S rRNA sequences.
Sequencing reads were de novo assembled into contigs and annotated. Samples corresponded to both clinically healthy and diseased individuals. We implemented a meta-transcriptomic approach to detect trypanosomes in a variety of tissues (brain, liver, lung, skin, gonads) sampled from native Australian wildlife, comprising four marsupials (koala, Phascolarctos cinereus southern brown bandicoot, Isoodon obesulus swamp wallaby, Wallabia bicolor bare-nosed wombat, Vombatus ursinus), one bird (regent honeyeater, Anthochaera phrygia) and one amphibian (eastern dwarf tree frog, Litoria fallax). The implementation of total RNA sequencing (meta-transcriptomics) in trypanosome surveillance and diagnosis provides a powerful methodological approach to better understand the host species distribution of this important group of parasites. The detection of trypanosome infection in native Australian fauna is central to understanding their diversity and host-parasite associations. Wildlife species carry a remarkable diversity of trypanosomes.
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