Academic literature on the topic 'Tasmanian devil – Parasites'

The impact of emerging infectious diseases is increasingly recognised as a major threat to wildlife. Wild populations of the endangered Tasmanian devil, Sarcophilus harrisii, are experiencing devastating losses from a novel transmissible cancer, devil facial tumour disease (DFTD); however, despite the rapid decline of this species, there is currently no information on the presence of haemoprotozoan parasites. In the present study, 95 Tasmanian devil blood samples were collected from four populations in Tasmania, Australia, which underwent molecular screening to detect four major groups of haemoprotozoa: (i) trypanosomes, (ii) piroplasms, (iii) Hepatozoon, and (iv) haemosporidia. Sequence results revealed Trypanosoma infections in 32/95 individuals. Trypanosoma copemani was identified in 10 Tasmanian devils from three sites and a second Trypanosoma sp. was identified in 22 individuals that were grouped within the poorly described T. cyclops clade. A single blood sample was positive for Babesia sp., which most closely matched Babesia lohae. No other blood protozoan parasite DNA was detected. This study provides the first insight into haemoprotozoa from the Tasmanian devil and the first identification of Trypanosoma and Babesia in this carnivorous marsupial.

Devil facial tumor disease (DFTD) encompasses two independent transmissible cancers that have killed the majority of Tasmanian devils. The cancer cells are derived from Schwann cells and are spread between devils during biting, a common behavior during the mating season. The Centers for Disease Control and Prevention (CDC) defines a parasite as “An organism that lives on or in a host organism and gets its food from, or at, the expense of its host.” Most cancers, including DFTD, live within a host organism and derive resources from its host, and consequently have parasitic-like features. Devil facial tumor disease is a transmissible cancer and, therefore, DFTD shares one additional feature common to most parasites. Through direct contact between devils, DFTD has spread throughout the devil population. However, unlike many parasites, the DFTD cancer cells have a simple lifecycle and do not have either independent, vector-borne, or quiescent phases. To facilitate a description of devil facial tumor disease, this review uses life cycles of parasites as an analogy.

Toxoplasma gondii is a cosmopolitan protozoan parasite of felids that also has significant implications for the health of wildlife, livestock and humans worldwide. In Australia, feral, stray and domestic cats (Felis catus) are the most important definitive host of T. gondii as they are the only species that can excrete the environmentally resistant oocysts that provide a major source of infection for mammals and birds. In Tasmania, the rapid decline of the Tasmanian devil (Sarcophilus harrisii) may allow an increase in feral cat abundance, thereby increasing the risk of T. gondii infection to a range of susceptible wildlife species. At present, there is scant information on the prevalence of T. gondii infection in feral cat populations across Tasmania. We tested feral cats from 13 regions across Tasmania for the presence of T. gondii–specific IgG antibodies using a modified agglutination test. Results were combined with serosurveys from three previous studies to enable a comparison of seroprevalence among 14 regions across Tasmania. We found that 84.2% (224 of 266) of cats tested positive for T. gondii IgG antibodies. This is among the highest rates of prevalence recorded from Australia, and significantly higher than for most other countries. Adult cats had higher seroprevalence than kittens but there was no difference between sexes. In Tasmania, seroprevalence was high in 12 of 14 regions (range: 79.3–100.0%), with only two regions (Tasman Island and Southern Tasmania) recording significantly lower seroprevalence (≤50%). This suggests a high risk of infection across Tasmania, and has significant implications for wildlife conservation should feral cat abundance increase with the ongoing declines in Tasmanian devils.

The emergence of Devil Facial Tumour Disease (DFTD), a highly contagious cancer, is driving Tasmanian devils ( Sarcophilus harrisii ) to extinction. The cancer is a genetically and chromosomally stable clonal cell line which is transmitted by biting during social interactions. In the present study, we explore the Devil Facial Tumour (DFT) epigenome and the genes involved in DNA methylation homeostasis. We show that tumour cells have similar levels of methylation to peripheral nerves, the tissue from which DFTD originated. We did not observe any strain or region-specific epimutations. However, we revealed a significant increase in hypomethylation in DFT samples over time ( p < 0.0001). We propose that loss of methylation is not because of a maintenance deficiency, as an upregulation of DNA methyltransferase 1 gene was observed in tumours compared with nerves ( p < 0.005). Instead, we believe that loss of methylation is owing to active demethylation, supported by the temporal increase in MBD2 and MBD4 ( p < 0.001). The implications of these changes on disease phenotypes need to be explored. Our work shows that DFTD should not be treated as a static entity, but rather as an evolving parasite with epigenetic plasticity. Understanding the role of epimutations in the evolution of this parasitic cancer will provide unique insights into the role of epigenetic plasticity in cancer evolution and progression in traditional cancers that arise and die with their hosts.

Adaptive management is driven by structured decision making and evidence from monitoring in a ‘learning’ framework that guides management actions. In a conservation context, this iterative approach includes evaluation of the impacts on natural processes. On Maria Island National Park, Tasmania, Australia, introduced Forester kangaroo, Bennetts wallaby and Tasmanian pademelon have been intensively managed by an annual cull since 1994. Management actions were triggered by high parasite loads, intense grazing pressure and high juvenile mortality during drought periods. Criticism of the annual cull from animal welfare groups initiated the development of an adaptive management approach for decision making that replaces the historic ‘trial and error’ process. Following a comprehensive review of the existing macropod management program in 2011, an integrated monitoring strategy was established to provide evidence for informed decision making. Assessments of animal health and estimates of population trends are the key indicators for management actions to occur. Maintaining viable macropod populations and protecting natural values form the basis of management objectives. Management actions in each year, for each species, represent ‘treatments’ as spatial replication is not possible at such a small scale. An adaptive management approach for macropod management on Maria Island has resulted in only one species being culled in 2014 and 2015 for the first time in almost 20 years. However the recent introduction of a major predator, the Tasmanian devil, has increased uncertainty for long-term macropod management on Maria Island with no cull occurring in 2016 and 2017.

Abstract The Tasmanian devil (Sarcophilus harrisii (Boitard)) is an endangered carnivorous marsupial, limited to the islands of Tasmania in southern Australia. The parasites of the Tasmanian devil are understudied. This study aimed to increase the knowledge of the nematode fauna of Tasmanian devils. Ten Tasmanian devils were examined for parasites from northern and southern Tasmania. Nematodes that were collected were morphologically characterized as two separate species. Molecular sequencing was undertaken to verify the identity of these species. A new genus and species of oxyurid nematode was collected from a single Tasmanian devil from the northern part of Tasmania. The nematode is differentiated from oxyurids described from other Australian amphibians, reptiles and marsupials by the characters of the male posterior end – that is, in having three pairs of caudal papillae, two pairs peri-cloacal, one large pair post-cloacal, a long tapering tail, a stout spicule and a gubernaculum and accessory piece, as well as its much larger overall size. Molecular sequencing was unsuccessful. The remaining nematodes collected from the Tasmanian devil in this study were all identified as Baylisascaris tasmaniensis Sprent, 1970, through morphology and molecular sequencing. This paper presents the first description of a new genus and species of oxyurid nematode from the Tasmanian devil, Sarcophiloxyuris longus n. gen., n. sp. The need to undertake more sampling of the parasites of endangered hosts, such as the Tasmanian devil, to assist with a better understanding of their conservation management, is discussed.

Abstract Ecoimmunology is a rapidly developing field that explores how the environment shapes immune function, which in turn influences host–parasite relationships and disease outcomes. Host immune defence is a key fitness determinant because it underlies the capacity of animals to resist or tolerate potential infections. Importantly, immune function can be suppressed, depressed, reconfigured or stimulated by exposure to rapidly changing environmental drivers like temperature, pollutants and food availability. Thus, hosts may experience trade-offs resulting from altered investment in immune function under environmental stressors. As such, approaches in ecoimmunology can provide powerful tools to assist in the conservation of wildlife. Here, we provide case studies that explore the diverse ways that ecoimmunology can inform and advance conservation efforts, from understanding how Galapagos finches will fare with introduced parasites, to using methods from human oncology to design vaccines against a transmissible cancer in Tasmanian devils. In addition, we discuss the future of ecoimmunology and present 10 questions that can help guide this emerging field to better inform conservation decisions and biodiversity protection. From better linking changes in immune function to disease outcomes under different environmental conditions, to understanding how individual variation contributes to disease dynamics in wild populations, there is immense potential for ecoimmunology to inform the conservation of imperilled hosts in the face of new and re-emerging pathogens, in addition to improving the detection and management of emerging potential zoonoses.

Tasmania’s apex predator the Tasmanian devil (Sarcophilus harrisii) is under threat from multiple sources including devil facial tumour disease (DFTD) and as a result is now classified as endangered. Thus, understanding other factors that can have an influence on health is vital as they can have ecosystem-wide effects. One such factor of interest is devil-parasite interactions. The present study analysed ticks and tick-borne protozoal pathogens of devils to gain an understanding of what haemoprotozoan pathogens are present in devils and ticks collected from them. Specifically, the present study aims to detect the presence and distribution of haemoprotozoan pathogens in (1) populations of wild Tasmanian devils with and without Tasmanian devil facial tumour disease and (2) ticks collected from wild devils. To achieve these aims the following objectives were created: (i) assess the species distribution and instar stage of collected ticks, (ii) determine the vectorial potential of these ticks and (iii) conduct phylogenetic analysis of any generated sequences. Samples were collected from DFTD infected and non-DFTD devils at five sites across mainland Tasmania, for which the DFTD status has been confirmed at different times in the past 20 years. Morphological and molecular techniques were utilised in this study to examine whole tick specimens for species and instar classification. Blood smears created were microscopically examined for inclusions of parasites and blood and tick genomic DNA extracted from all samples, screened by PCR and positives sequenced using Sanger sequencing and phylogenetically analysed. Samples from DFTD and non-DFTD infected devils successfully amplified on short (~300bp) and long (~1500bp) 18S rRNA assays but no statistical difference was observed between DFTD and non-DFTD devils on either assay. Sequencing and phylogenetic analysis of a subset of samples revealed a Babesia sp. infection consistent with B. lohae on the short amplification, while on the long assay four novel sequences were revealed from one site. Phylogenetic analysis of these novel sequences confirmed their genetic distinctness, as for three of them the closest species match was only 85.7% to 85.9% similar to Stylocephalus giganteus (FJ459761) and the fourth sequence exhibited only 89.2% similarity to Theileria ornithorhynchi (KT937391). Morphological identifications revealed Tasmanian devils in the present study were infected with all instars of Ixodes sp. ticks and all specimens identified to species level were either I. tasmani or I. fecialis, with I. tasmani the most prevalent. Analysis of genomic DNA extracts of ticks on short (~300bp) and long (~1500bp) assays of the 18S rRNA locus revealed infections of Hepatozoon banethi, Theileria spp. and a sequence 85.8% similar to Stylocephalus giganteus (FJ459761). The present study documents the first characterisations of haemoprotozoan pathogens in Tasmanian devils, with the discovery of a Babesia spp. sequence and the first observation of Theileria spp. from ticks collected from Tasmanian devils. Molecular screening of both tick and devil genomic DNA also found evidence of novel apicomplexan sequences.