ORCID Profile
0000-0003-4395-4069
Current Organisation
Murdoch University
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Publisher: Wiley
Date: 31-01-2023
DOI: 10.1111/MVE.12643
Abstract: Ticks (Acari: Ixodidae) are major disease vectors globally making it increasingly important to understand how altered vertebrate communities in urban areas shape tick population dynamics. In urban landscapes of Australia, little is known about which native and introduced small mammals maintain tick populations preventing host‐targeted tick management and leading to human–wildlife conflict. Here, we determined (1) larval, nymphal, and adult tick burdens on host species and potential drivers, (2) the number of ticks supported by the different host populations, and (3) the proportion of medically significant tick species feeding on the different host species in Northern Sydney. We counted 3551 ticks on 241 mammals at 15 sites and found that long‐nosed bandicoots ( Perameles nasuta ) hosted more ticks of all life stages than other small mammals but introduced black rats ( Rattus rattus ) were more abundant at most sites (33%–100%) and therefore important in supporting larval and nymphal ticks in our study areas. Black rats and bandicoots hosted a greater proportion of medically significant tick species including Ixodes holocyclus than other hosts. Our results show that an introduced human commensal contributes to maintaining urban tick populations and suggests ticks could be managed by controlling rat populations on urban fringes.
Publisher: Microbiology Society
Date: 16-12-2021
Abstract: Advances in sequencing technologies have revealed the complex and erse microbial communities present in ticks (Ixodida). As obligate blood-feeding arthropods, ticks are responsible for a number of infectious diseases that can affect humans, livestock, domestic animals and wildlife. While cases of human tick-borne diseases continue to increase in the northern hemisphere, there has been relatively little recognition of zoonotic tick-borne pathogens in Australia. Over the past 5 years, studies using high-throughput sequencing technologies have shown that Australian ticks harbour unique and erse bacterial communities. In the present study, free-ranging wildlife ( n =203), representing ten mammal species, were s led from urban and peri-urban areas in New South Wales (NSW), Queensland (QLD) and Western Australia (WA). Bacterial metabarcoding targeting the 16S rRNA locus was used to characterize the microbiomes of three s le types collected from wildlife: blood, ticks and tissue s les. Further sequence information was obtained for selected taxa of interest. Six tick species were identified from wildlife: Amblyomma triguttatum , Ixodes antechini , Ixodes australiensis , Ixodes holocyclus , Ixodes tasmani and Ixodes trichosuri . Bacterial 16S rRNA metabarcoding was performed on 536 s les and 65 controls, generating over 100 million sequences. Alpha ersity was significantly different between the three s le types, with tissue s les displaying the highest alpha ersity ( P .001). Proteobacteria was the most abundant taxon identified across all s le types (37.3 %). Beta ersity analysis and ordination revealed little overlap between the three s le types ( P .001). Taxa of interest included Anaplasmataceae , Bartonella , Borrelia , Coxiellaceae , Francisella , Midichloria , Mycoplasma and Rickettsia . Anaplasmataceae bacteria were detected in 17.7% (95/536) of s les and included Anaplasma , Ehrlichia and Neoehrlichia species. In s les from NSW, ‘ Ca . Neoehrlichia australis’, ‘ Ca . Neoehrlichia arcana’, Neoehrlichia sp. and Ehrlichia sp. were identified. A putative novel Ehrlichia sp. was identified from WA and Anaplasma platys was identified from QLD. Nine rodent tissue s les were positive for a novel Borrelia sp. that formed a phylogenetically distinct clade separate from the Lyme Borrelia and relapsing fever groups. This novel clade included recently identified rodent-associated Borrelia genotypes, which were described from Spain and North America. Bartonella was identified in 12.9% (69/536) of s les. Over half of these positive s les were obtained from black rats ( Rattus rattus ), and the dominant bacterial species identified were Bartonella coopersplainsensis and Bartonella queenslandensis . The results from the present study show the value of using unbiased high-throughput sequencing applied to s les collected from wildlife. In addition to understanding the sylvatic cycle of known vector-associated pathogens, surveillance work is important to ensure preparedness for potential zoonotic spillover events.
Publisher: Cambridge University Press (CUP)
Date: 28-09-2020
DOI: 10.1017/S0031182020001845
Abstract: Trypanosomes are blood-borne parasites that can infect a variety of different vertebrates, including animals and humans. This study aims to broaden scientific knowledge about the presence and bio ersity of trypanosomes in Australian bats. Molecular and morphological analysis was performed on 86 blood s les collected from seven different species of microbats in Western Australia. Phylogenetic analysis on 18S rDNA and glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) sequences identified Trypanosoma dionisii in five different Australian native species of microbats Chalinolobus gouldii, Chalinolobus morio, Nyctophilus geoffroyi, Nyctophilus major and Scotorepens balstoni . In addition, two novels, genetically distinct T. dionisii genotypes were detected and named T. dionisii genotype Aus 1 and T. dionisii genotype Aus 2. Genotype Aus 2 was the most prevalent and infected 20.9% (18/86) of bats in the present study, while genotype Aus 1 was less prevalent and was identified in 5.8% (5/86) of Australian bats. Morphological analysis was conducted on trypomastigotes identified in blood films, with morphological parameters consistent with trypanosome species in the subgenus Schizotrypanum. This is the first report of T. dionisii in Australia and in Australian native bats, which further contributes to the global distribution of this cosmopolitan bat trypanosome.
Publisher: Cold Spring Harbor Laboratory
Date: 17-10-2019
DOI: 10.1101/807131
Abstract: Ticks (Acari: Ixodida) transmit a greater variety of pathogens than any other blood-feeding group of arthropods. While numerous microbes have been identified inhabiting Australian Ixodidae, some of which are related to globally important tick-borne pathogens, little is known about the bacterial communities within ticks collected from Australian wildlife. In this study, 1,019 ticks were identified on 221 hosts spanning 27 wildlife species. Next-generation sequencing was used to lify the V1-2 hypervariable region of the bacterial 16S rRNA gene from 238 ticks Amblyomma triguttatum (n=6), Bothriocroton auruginans (n=11), Bothriocroton concolor (n=20), Haemaphysalis bancrofti (n=10), Haemaphysalis bremneri (n=4), Haemaphysalis humerosa (n=13) , Haemaphysalis longicornis (n=4), Ixodes antechini (n=29), Ixodes australiensis (n=26), Ixodes fecialis (n=13), Ixodes holocyclus (n=37), Ixodes myrmecobii ( n =1), Ixodes ornithorhynchi (n=10), Ixodes tasmani (n=51) and Ixodes trichosuri (n=3). After bioinformatic analyses, over 14 million assigned bacterial sequences revealed the presence of recently described bacteria ‘ Candidatus Borrelia tachyglossi’, ‘ Candidatus Neoehrlichia australis’, ‘ Candidatus Neoehrlichia arcana’ and ‘ Candidatus Ehrlichia ornithorhynchi’. Furthermore, three novel Anaplasmataceae species were identified in the present study including a Neoehrlichia sp. in I. australiensis and I. fecialis collected from quenda ( Isoodon fusciventer ) (Western Australia), an Anaplasma sp. from one B. concolor from echidna ( Tachyglossus aculeatus ) (New South Wales), and an Ehrlichia sp. from a single I. fecialis parasitising a quenda (WA). This study highlights the ersity of bacterial genera harboured within wildlife ticks, which may prove to be of medical and/or veterinary importance in the future.
Publisher: Wiley
Date: 17-01-2021
DOI: 10.1111/ZPH.12806
Publisher: MDPI AG
Date: 19-10-2023
Publisher: Elsevier BV
Date: 2022
DOI: 10.1016/J.TTBDIS.2021.101873
Abstract: Ticks are haematophagous arthropods that parasitise a wide range of vertebrate hosts. In Australia, there are currently 74 tick species described 22 tick species have been reported parasitising humans. The stump-tailed lizard tick, Amblyomma albolimbatum, feeds on reptiles, most commonly lizards and snakes however, we report the first case of A. albolimbatum parasitising a human. The nymphal tick was removed while conducting fieldwork on western tiger snakes (Notechis scutatus occidentalis) in an urban city environment near Perth, Western Australia. The tick was identified using morphological descriptions, which was further supported by the abundance of all parasitic stages of A. albolimbatum on the tiger snakes s led. The number of tick species recorded from humans in Australia is now revised to 23 species. With the increasing incidence of tick-borne illnesses in Australia, this study highlights the need to report cases of new or atypical hosts, particularly humans, and especially when the ticks have been associated with zoonotic pathogens.
Publisher: Magnolia Press
Date: 14-08-2019
DOI: 10.11646/ZOOTAXA.4656.2.13
Abstract: Ticks (Ixodida) are haematophagous arthropods that transmit a number of pathogenic organisms, including bacteria, protozoa and viruses, to humans and animals. Globally, there are over 900 species of ticks and Australia has 73 described species, including five introduced and 68 native species. With the exception of only a few Australian tick species, there are still many unanswered questions regarding their taxonomy and systematics, and the phylogeny of Australian ticks is not properly resolved. In recent years, a putative link between tick bites and poorly defined tick-borne illness(es) has been identified (Graves & Stenos 2017) and was the subject of a 2015 Australian Senate Inquiry into Lyme-like illnesses in Australia. There is an urgent need to further categorise Australian ticks, specifically hard ticks (Ixodidae), and accurate identification of Australian ticks is therefore of high importance.
Publisher: Elsevier BV
Date: 09-2020
Publisher: American Chemical Society (ACS)
Date: 12-09-2022
Publisher: Springer Science and Business Media LLC
Date: 20-03-2019
Publisher: Wildlife Disease Association
Date: 05-07-2021
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 08-2018
Publisher: MDPI AG
Date: 23-10-2020
Abstract: 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 s les 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 in iduals. Trypanosoma copemani was identified in 10 Tasmanian devils from three sites and a second Trypanosoma sp. was identified in 22 in iduals that were grouped within the poorly described T. cyclops clade. A single blood s le 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.
Publisher: Elsevier BV
Date: 08-2021
DOI: 10.1016/J.MEEGID.2021.104859
Abstract: Cryptosporidium is an important protozoan parasite and due to its resistance to chlorine is a major cause of swimming pool-associated gastroenteritis outbreaks. The present study combined contact tracing and molecular techniques to analyse cryptosporidiosis cases and outbreaks in Western Australia in 2019 and 2020. In the 2019 outbreak, subtyping at the 60 kDa glycoprotein (gp60) gene identified 89.0% (16/18) of s les were caused by the C. hominis IdA15G1 subtype. Amplicon next generation sequencing (NGS) at the gp60 locus identified five C. hominis IdA15G1 subtype s les that also had C. hominis IdA14 subtype DNA, while multi locus sequence typing (MLST) analysis on a subset (n = 14) of C. hominis s les identified three IdA15G1 s les with a 6 bp insertion at the end of the trinucleotide repeat region of the cp47 gene. In 2020, 88.0% (73/83) of s les typed were caused by the relatively rare C. hominis subtype IbA12G3. Four mixed infections were observed by NGS with three IdA15G1/ IdA14 mixtures and one C. parvum IIaA18G3R1 s le mixed with IIaA16G3R1. No genetic ersity using MLST was detected. Epidemiological and molecular data indicates that the outbreaks in 2019 and 2020 were each potentially from swimming pool point sources and a new C. hominis subtype IbA12G3 is emerging in Australia. The findings of the present study are important for understanding the introduction and transmission of rare Cryptosporidium subtypes to vulnerable populations.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/MA18063
Abstract: It may seem perplexing that there is any uncertainty in Australia about the existence of zoonotic tick-associated infections1–3. Outside this country, particularly in the northern hemisphere, tick-borne diseases such as human granulocytic anaplasmosis, babesiosis, Boutonneuse fever, ehrlichiosis, Lyme borreliosis, and tick-borne encephalitis, have well documented aetiologies, epidemiology, diagnostic methods, and treatments. Why is Australia different and what research is being conducted to address this issue? This article briefly addresses these questions and explains how high-throughput metagenomic analysis has started to shed light on bacterial microbiomes in Australian ticks, providing new data on the presence and distribution of potentially zoonotic microbial taxa.
Publisher: MDPI AG
Date: 20-07-2022
DOI: 10.3390/MICROORGANISMS10071464
Abstract: Industrial production of synthetic nitrogen fertilizers and their crop application have caused considerable environmental impacts. Some eco-friendly alternatives try to solve them but raise some restrictions. We tested a novel method to produce a nitrogen bioinoculant by enriching a soil microbial community in bioreactors supplying N2 by air pumping. The biomass enriched with diazotrophic bacteria was diluted and applied to N-depleted and sterilized soil of tomato plants. We estimated microbial composition and ersity by 16S rRNA metabarcoding from soil and bioreactors at different run times and during plant uprooting. Bioreactors promoted the N-fixing microbial community and revealed a hided ersity. One hundred twenty-four (124) operational taxonomic units (OTUs) were assigned to bacteria with a greater Shannon ersity during the reactor’s steady state. A total of 753 OTUs were found in the rhizospheres with higher bio ersity when the lowest concentration of bacteria was applied. The apparent bacterial abundance in the batch and continuous bioreactors suggested a more specific functional ecological organization. We demonstrate the usefulness of bioreactors to evidence hidden ersity in the soil when it passes through bioreactors. By obtaining the same growth of inoculated plants and the control with chemical synthesis fertilizers, we evidence the potential of the methodology that we have called directed bioprospecting to grow a complex nitrogen-fixing microbial community. The simplicity of the reactor’s operation makes its application promising for developing countries with low technological progress.
Publisher: Cold Spring Harbor Laboratory
Date: 05-11-2019
DOI: 10.1101/819060
Abstract: Invasive rodent species are known hosts for a erse range of infectious microorganisms and have long been associated with the spread of disease globally. The present study describes molecular evidence for the presence of a Trypanosoma sp. from black rats ( Rattus rattus ) in northern Sydney, Australia. Sequences of the 18S ribosomal RNA (rRNA) locus were obtained in two out of eleven (18%) blood s les with subsequent phylogenetic analysis confirming the identity within the Trypanosoma lewisi clade.
No related grants have been discovered for Siobhon Egan.