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1.
J Health Care Chaplain ; : 1-14, 2023 Oct 09.
Article in English | MEDLINE | ID: mdl-37811644

ABSTRACT

The aim of this pilot study was to test an effort to provide spiritual care (SC) to oncology outpatients in the Ascension healthcare system. Medical providers referred patients who would benefit from spiritual and emotional support. Twenty-seven cancer outpatients from 5 states were enrolled in the project. Based on the chaplain assessment, 45% of the patients had moderate or severe spiritual concerns. On average patients had 4 sessions with a chaplain (range 2-9). Of the 136 chaplain sessions, 56% were in-person in the clinic and 35% were by phone. The most common chaplain activities were active listening (87% of the sessions) and demonstrate caring and concern (55%). For the 20 patients who provided follow-up data, there were decreases in all measures of religious/spiritual distress, though statistically insignificant, and a marginally significant increase (p < .054) in well-being. The study adds to the emerging literature that describes the importance of SC in the outpatient context.

2.
Polymers (Basel) ; 15(4)2023 Feb 10.
Article in English | MEDLINE | ID: mdl-36850162

ABSTRACT

Efforts to mitigate the effects of feral cats through the management of remnant or reintroduced populations of threatened species, are often unsuccessful due to predation by control-averse feral cats, or 'problem individuals'. In order to target these animals, we have developed the Population Protecting Implant (PPI). PPIs are designed to be implanted subcutaneously in a native animal. If the animal is preyed upon, and the implant ingested by a feral cat, release of a toxic payload is triggered in the acidic stomach environment and the problem individual is eliminated. We introduce the first toxic implant incorporating the poison sodium fluoroacetate. Manufactured via fluidised-bed spray coating, toxic implants exhibited uniform reverse enteric coatings and low intra-batch variation. Toxic implants were found to exhibit favourable stability at subcutaneous pH in vitro, and rapidly release their toxic payload in vitro at gastric pH. However, limited stability was demonstrated in rats in vivo (~39-230 d), due to the use of a filament scaffold to enable coating and was likely exacerbated by metachromatic interactions caused by 1080. This work highlights that future development of the PPIs should primarily focus on removal of the filament scaffold, to afford implants with increased in vivo stability.

3.
Parasitol Int ; 91: 102642, 2022 Dec.
Article in English | MEDLINE | ID: mdl-35944836

ABSTRACT

To genetically assess the Australian distribution and frequency of Eimeria species in wild rabbits, with a primary focus on Eimeria intestinalis and Eimeria flavescens as possible additional agents of rabbit biocontrol, the distal colon and faecal samples from wild rabbits sourced from 26 Australian locations with mean annual rainfalls of between 252 mm and 925 mm were analysed using amplicon sequencing of the ITS1 region. Contrary to previous microscopy studies which had only detected E. flavescens on mainland Australia at Wellstead in south-west Western Australia, we detected this species at all 23 effectively sampled sites. The more pathogenic E. intestinalis was only found at 52.2% of sites. Three unique Eimeria genotypes were detected that did not align to the 11 published sequences using a pairwise-match threshold of 90%, and may represent unsequenced known species or novel species. One genotype we termed E. Au19SH and was detected at 20 sites, E. Au19CO was detected at eight sites, and E. Au19CN was detected in one rabbit at Crows Nest (Qld). Site diversity ranged from only five Eimeria species at Boboyan (ACT) to 13 unique sequences at Cargo (NSW). Eimeria diversity in individual rabbits ranged from 11 unique sequences in a rabbit at Wellstead (WA) and a rabbit at Cargo (NSW), to one in 17 rabbits and zero in six rabbits. The three rabbit age classes averaged 4.3 Eimeria species per rabbit. No relationship was found between the number of Eimeria species detected and mean annual rainfall. As Eimeria species were found to be fairly ubiquitous at most sites they appear to be an unlikely additional candidate to assist the control of pest rabbits in Australia.


Subject(s)
Coccidiosis , Eimeria , Animals , Australia/epidemiology , Coccidiosis/epidemiology , Coccidiosis/veterinary , Eimeria/genetics , Feces , Prevalence , Rabbits
4.
Animals (Basel) ; 11(11)2021 Oct 31.
Article in English | MEDLINE | ID: mdl-34827857

ABSTRACT

Movements that extend beyond the usual space use of an animal have been documented in a range of species and are particularly prevalent in arid areas. We present long-distance movement data on five feral cats (Felis catus) GPS/VHF-collared during two different research projects in arid and semi-arid Australia. We compare these movements with data from other feral cat studies. Over a study period of three months in the Ikara-Flinders Ranges National Park, 4 out of 19 collared cats moved to sites that were 31, 41, 53 and 86 km away. Three of the cats were males, one female; their weight was between 2.1 and 4.1 kg. Two of the cats returned to the area of capture after three and six weeks. During the other study at Arid Recovery, one collared male cat (2.5 kg) was relocated after two years at a distance of 369 km from the area of collar deployment to the relocation area. The movements occurred following three years of record low rainfall. Our results build on the knowledge base of long-distance movements of feral cats reported at arid study sites and support the assertion that landscape-scale cat control programs in arid and semi-arid areas need to be of a sufficiently large scale to avoid rapid reinvasion and to effectively reduce cat density. Locally, cat control strategies need to be adjusted to improve coverage of areas highly used by cats to increase the efficiency of control operations.

5.
J Parasitol ; 107(4): 554-561, 2021 07 01.
Article in English | MEDLINE | ID: mdl-34270758

ABSTRACT

Parasite infection pressure is suggested to be a strong driver of transmission within ecosystems. We tested if infection pressure drives seroprevalence in intermediate host species for Toxoplasma gondii. We defined Toxoplasma infection pressure to intermediate host species as the combined influence of cat abundance, environmental conditions, and its prevalence in the cat population. We sampled and tested 2 species of rodent and collated information on Toxoplasma seroprevalence in koalas, wallabies, kangaroos, and sheep. All species were sampled using equivalent methods, within a 2-yr period, and from adjacent regions of low and high Toxoplasma infection pressure. The seroprevalence of Toxoplasma in kangaroos scaled with infection pressure, but we observed no statistical difference in seroprevalence for any other species between these 2 regions. Within the region of low infection pressure, Toxoplasma seroprevalence did not differ between species. However, within the region of high Toxoplasma infection pressure, we observed large variation in seroprevalence between species. Our results demonstrate that infection pressure is not sufficient by itself, but merely necessary, to drive Toxoplasma seroprevalence in intermediate host species. Where Toxoplasma seroprevalence in an intermediate host species is already low, further reducing infection pressure will not necessarily further decrease seroprevalence in those species. This has important ramifications for the mitigation of parasite infections and suggests that reductions in Toxoplasma infection pressure, intended to reduce infections, may be most effective and applicable to species that are known to experience high rates of infection.


Subject(s)
Toxoplasma/immunology , Toxoplasmosis, Animal/epidemiology , Animals , Antibodies, Protozoan/blood , Cats , Macropodidae , Mice , Phascolarctidae , Rabbits , Rats , Seroepidemiologic Studies , Sheep , South Australia/epidemiology , Toxoplasmosis, Animal/transmission
6.
Mol Ecol ; 29(19): 3777-3794, 2020 10.
Article in English | MEDLINE | ID: mdl-32506669

ABSTRACT

Since its introduction to control overabundant invasive European rabbits (Oryctolagus cuniculus), the highly virulent rabbit haemorrhagic disease virus (RHDV) has caused regular annual disease outbreaks in Australian rabbit populations. Although initially reducing rabbit abundance by 60%, continent-wide, experimental evidence has since indicated increased genetic resistance in wild rabbits that have experienced RHDV-driven selection. To identify genetic adaptations, which explain the increased resistance to this biocontrol virus, we investigated genome-wide SNP (single nucleotide polymorphism) allele frequency changes in a South Australian rabbit population that was sampled in 1996 (pre-RHD genomes) and after 16 years of RHDV outbreaks. We identified several SNPs with changed allele frequencies within or close to genes potentially important for increased RHD resistance. The identified genes are known to be involved in virus infections and immune reactions or had previously been identified as being differentially expressed in healthy versus acutely RHDV-infected rabbits. Furthermore, we show in a simulation study that the allele/genotype frequency changes cannot be explained by drift alone and that several candidate genes had also been identified as being associated with surviving RHD in a different Australian rabbit population. Our unique data set allowed us to identify candidate genes for RHDV resistance that have evolved under natural conditions, and over a time span that would not have been feasible in an experimental setting. Moreover, it provides a rare example of host genetic adaptations to virus-driven selection in response to a suddenly emerging infectious disease.


Subject(s)
Caliciviridae Infections , Epidemics , Hemorrhagic Disease Virus, Rabbit , Animals , Australia/epidemiology , Caliciviridae Infections/epidemiology , Caliciviridae Infections/genetics , Caliciviridae Infections/veterinary , Genotype , Hemorrhagic Disease Virus, Rabbit/genetics , Rabbits
7.
Animals (Basel) ; 9(9)2019 Aug 28.
Article in English | MEDLINE | ID: mdl-31466221

ABSTRACT

This review examines the social aspects that influence feral cat management. In particular, it examines definitions and perceptions of feral cats as a species in different countries and across cultures. Using case studies from around the world, we investigate the factors that can influence public perceptions and social acceptance of feral cats and management methods. The review then highlights the importance of social factors in management and suggests the best approach to use in the future to ease the process of gaining a social license for management campaigns. Implications of the influence of education and awareness on public perception and acceptance are further explained, and are suggested to be an essential tool in successfully engaging the community about management in the future.

8.
Ecology ; 100(7): e02750, 2019 07.
Article in English | MEDLINE | ID: mdl-31034589

ABSTRACT

With ongoing introductions into Australia since the 1700s, the European rabbit (Oryctolagus cuniculus) has become one of the most widely distributed and abundant vertebrate pests, adversely impacting Australia's biodiversity and agroeconomy. To understand the population and range dynamics of the species and its impacts better, occurrence and abundance data have been collected by researchers and citizens from sites covering a broad spectrum of climatic and environmental conditions in Australia. The lack of a common and accessible repository for these data has, however, limited their use in determining important spatiotemporal drivers of the structure and dynamics of the geographical range of rabbits in Australia. To meet this need, we created the Australian National Rabbit Database, which combines more than 50 yr of historical and contemporary survey data collected from throughout the range of the species in Australia. The survey data, obtained from a suite of complementary monitoring methods, were combined with high-resolution weather, climate, and environmental information, and an assessment of data quality. The database provides records of rabbit occurrence (689,265 records) and abundance (51,241 records, >120 distinct sites) suitable for identifying the spatiotemporal drivers of the rabbit's distribution and for determining spatial patterns of variation in its key life-history traits, including maximum rates of population growth. Because all data are georeferenced and date stamped, they can be coupled with information from other databases and spatial layers to explore the potential effects of rabbit occurrence and abundance on Australia's native wildlife and agricultural production. The Australian National Rabbit Database is an important tool for understanding and managing the European rabbit in its invasive range and its effects on native biodiversity and agricultural production. It also provides a valuable resource for addressing questions related to the biology, success, and impacts of invasive species more generally. No copyright or proprietary restrictions are associated with the use of this data set other than citation of this Data Paper.

9.
J Virol ; 93(8)2019 04 15.
Article in English | MEDLINE | ID: mdl-30728252

ABSTRACT

Myxoma virus (MYXV) has been evolving in a novel host species-European rabbits-in Australia since 1950. Previous studies of viruses sampled from 1950 to 1999 revealed a remarkably clock-like evolutionary process across all Australian lineages of MYXV. Through an analysis of 49 newly generated MYXV genome sequences isolated in Australia between 2008 and 2017, we show that MYXV evolution in Australia can be characterized by three lineages, one of which exhibited a greatly elevated rate of evolutionary change and a dramatic breakdown of temporal structure. Phylogenetic analysis revealed that this apparently punctuated evolutionary event occurred between 1996 and 2012. The branch leading to the rapidly evolving lineage contained a relatively high number of nonsynonymous substitutions, and viruses in this lineage reversed a mutation found in the progenitor standard laboratory strain (SLS) and all previous sequences that disrupts the reading frame of the M005L/R gene. Analysis of genes encoding proteins involved in DNA synthesis or RNA transcription did not reveal any mutations likely to cause rapid evolution. Although there was some evidence for recombination across the MYXV phylogeny, this was not associated with the increase in the evolutionary rate. The period from 1996 to 2012 saw significant declines in wild rabbit numbers, due to the introduction of rabbit hemorrhagic disease and prolonged drought in southeastern Australia, followed by the partial recovery of populations. It is therefore possible that a rapidly changing environment for virus transmission changed the selection pressures faced by MYXV, altering the course and pace of virus evolution.IMPORTANCE The coevolution of myxoma virus (MYXV) and European rabbits in Australia is one of the most important natural experiments in evolutionary biology, providing insights into virus adaptation to new hosts and the evolution of virulence. Previous studies of MYXV evolution have also shown that the virus evolves both relatively rapidly and in a strongly clock-like manner. Using newly acquired MYXV genome sequences from Australia, we show that the virus has experienced a dramatic change in evolutionary behavior over the last 20 years, with a breakdown in clock-like structure, the appearance of a rapidly evolving virus lineage, and the accumulation of multiple nonsynonymous and indel mutations. We suggest that this punctuated evolutionary event may reflect a change in selection pressures as rabbit numbers declined following the introduction of rabbit hemorrhagic disease virus and drought in the geographic regions inhabited by rabbits.


Subject(s)
Evolution, Molecular , Genes, Viral , Myxoma virus/genetics , Open Reading Frames , Phylogeny , Poxviridae Infections , Animals , Australia , Poxviridae Infections/genetics , Poxviridae Infections/veterinary , Rabbits , Time Factors , Viral Proteins/genetics , Whole Genome Sequencing
10.
J Wildl Dis ; 54(3): 544-547, 2018 07.
Article in English | MEDLINE | ID: mdl-29667872

ABSTRACT

Digital media and digital search tools offer simple and effective means to monitor for pathogens and disease outbreaks in target organisms. Using tools such as Rich Site Summary feeds, and Google News and Google Scholar specific key word searches, international digital media were actively monitored from 2012 to 2016 for pathogens and disease outbreaks in the taxonomic order Lagomorpha, with a specific focus on the European rabbit ( Oryctolagus cuniculus). The primary objective was identifying pathogens for assessment as potential new biocontrol agents for Australia's pest populations of the European rabbit. A number of pathogens were detected in digital media reports. Additional benefits arose in the regular provision of case reports and research on myxomatosis and rabbit haemorrhagic disease virus that assisted with current research.


Subject(s)
Caliciviridae Infections/veterinary , Disease Outbreaks/veterinary , Internet , Myxomatosis, Infectious/epidemiology , Rabbits , Animals , Animals, Wild , Australia/epidemiology , Caliciviridae Infections/epidemiology , Hemorrhagic Disease Virus, Rabbit , Myxoma virus , Population Surveillance
11.
Vet Rec ; 182(20): 574, 2018 05 19.
Article in English | MEDLINE | ID: mdl-29519856

ABSTRACT

Lagovirus europaeus GI.2, also commonly known as rabbit haemorrhagic disease virus 2, was first detected at two long-term monitoring sites for European rabbits, Oryctolagus cuniculus, in South Australia, in mid-2016. Numbers of rabbits in the following 12-18 months were reduced to approximately 20 per cent of average numbers in the preceding 10 years. The impact recorded at the two South Australian sites, if widespread in Australia and persistent for several years, is likely to be of enormous economic and environmental benefit.


Subject(s)
Caliciviridae Infections/veterinary , Hemorrhagic Disease Virus, Rabbit/isolation & purification , Animals , Australia , Caliciviridae Infections/virology , Hemorrhagic Disease Virus, Rabbit/genetics , Population Dynamics , Rabbits
12.
J Virol ; 92(2)2018 01 15.
Article in English | MEDLINE | ID: mdl-29093089

ABSTRACT

Rabbit hemorrhagic disease virus 2 (RHDV2; Lagovirus GI.2) is a pathogenic calicivirus that affects European rabbits (Oryctolagus cuniculus) and various hare (Lepus) species. GI.2 was first detected in France in 2010 and subsequently caused epidemics in wild and domestic lagomorph populations throughout Europe. In May 2015, GI.2 was detected in Australia. Within 18 months of its initial detection, GI.2 had spread to all Australian states and territories and rapidly became the dominant circulating strain, replacing Rabbit hemorrhagic disease virus (RHDV/GI.1) in mainland Australia. Reconstruction of the evolutionary history of 127 Australian GI.2 isolates revealed that the virus arrived in Australia at least several months before its initial description and likely circulated unnoticed in wild rabbit populations in the east of the continent prior to its detection. GI.2 sequences isolated from five hares clustered with sequences from sympatric rabbit populations sampled contemporaneously, indicating multiple spillover events into hares rather than an adaptation of the Australian GI.2 to a new host. Since the presence of GI.2 in Australia may have wide-ranging consequences for rabbit biocontrol, particularly with the release of the novel biocontrol agent GI.1a/RHDVa-K5 in March 2017, ongoing surveillance is critical to understanding the interactions of the various lagoviruses in Australia and their impact on host populations.IMPORTANCE This study describes the spread and distribution of Rabbit hemorrhagic disease virus 2 (GI.2) in Australia since its first detection in May 2015. Within the first 18 months following its detection, RHDV2 spread from east to west across the continent and became the dominant strain in all mainland states of Australia. This has important implications for pest animal management and for owners of pet and farmed rabbits, as there currently is no effective vaccine available in Australia for GI.2. The closely related RHDV (GI.1) is used to control overabundant wild rabbits, a serious environmental and agricultural pest in this country, and it is currently unclear how the widespread circulation of GI.2 will impact ongoing targeted wild rabbit management operations.


Subject(s)
Caliciviridae Infections/epidemiology , Endemic Diseases/veterinary , Hemorrhagic Disease Virus, Rabbit/classification , Whole Genome Sequencing/methods , Animals , Australia/epidemiology , Caliciviridae Infections/veterinary , Caliciviridae Infections/virology , Europe/epidemiology , Genome, Viral , Genotype , Hares , Hemorrhagic Disease Virus, Rabbit/genetics , Phylogeny , Phylogeography , Rabbits , Sequence Analysis, RNA
13.
Mol Ecol ; 26(17): 4551-4561, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28667769

ABSTRACT

Deciphering the genes involved in disease resistance is essential if we are to understand host-pathogen coevolutionary processes. The rabbit haemorrhagic disease virus (RHDV) was imported into Australia in 1995 as a biocontrol agent to manage one of the most successful and devastating invasive species, the European rabbit (Oryctolagus cuniculus). During the first outbreaks of the disease, RHDV caused mortality rates of up to 97%. Recently, however, increased genetic resistance to RHDV has been reported. Here, we have aimed to identify genomic differences between rabbits that survived a natural infection with RHDV and those that died in the field using a genomewide next-generation sequencing (NGS) approach. We detected 72 SNPs corresponding to 133 genes associated with survival of a RHD infection. Most of the identified genes have known functions in virus infections and replication, immune responses or apoptosis, or have previously been found to be regulated during RHD. Some of the genes identified in experimental studies, however, did not seem to play a role under natural selection regimes, highlighting the importance of field studies to complement the genomic background of wildlife diseases. Our study provides a set of candidate markers as a tool for the future scanning of wild rabbits for their resistance to RHDV. This is important both for wild rabbit populations in southern Europe where RHD is regarded as a serious problem decimating the prey of endangered predator species and for assessing the success of currently planned RHDV variant biocontrol releases in Australia.


Subject(s)
Caliciviridae Infections/genetics , Caliciviridae Infections/veterinary , Disease Resistance/genetics , Rabbits/genetics , Animals , Animals, Wild/genetics , Animals, Wild/virology , Australia , Biological Control Agents , Hemorrhagic Disease Virus, Rabbit , Rabbits/virology
14.
J Gen Virol ; 98(7): 1658-1666, 2017 Jul.
Article in English | MEDLINE | ID: mdl-28714849

ABSTRACT

Lagoviruses belong to the Caliciviridae family. They were first recognized as highly pathogenic viruses of the European rabbit (Oryctolagus cuniculus) and European brown hare (Lepus europaeus) that emerged in the 1970-1980s, namely, rabbit haemorrhagic disease virus (RHDV) and European brown hare syndrome virus (EBHSV), according to the host species from which they had been first detected. However, the diversity of lagoviruses has recently expanded to include new related viruses with varying pathogenicity, geographic distribution and host ranges. Together with the frequent recombination observed amongst circulating viruses, there is a clear need to establish precise guidelines for classifying and naming lagovirus strains. Therefore, here we propose a new nomenclature based on phylogenetic relationships. In this new nomenclature, a single species of lagovirus would be recognized and called Lagovirus europaeus. The species would be divided into two genogroups that correspond to RHDV- and EBHSV-related viruses, respectively. Genogroups could be subdivided into genotypes, which could themselves be subdivided into phylogenetically well-supported variants. Based on available sequences, pairwise distance cutoffs have been defined, but with the accumulation of new sequences these cutoffs may need to be revised. We propose that an international working group could coordinate the nomenclature of lagoviruses and any proposals for revision.


Subject(s)
Lagovirus/classification , RNA, Viral/genetics , Terminology as Topic , Animals , Caliciviridae Infections/virology , Genotype , Hares , Lagovirus/genetics , Lagovirus/pathogenicity , Phylogeny , Rabbits
15.
J R Soc Interface ; 12(103)2015 Feb 06.
Article in English | MEDLINE | ID: mdl-25566883

ABSTRACT

Infectious diseases can exert a strong influence on the dynamics of host populations, but it remains unclear why such disease-mediated control only occurs under particular environmental conditions. We used 16 years of detailed field data on invasive European rabbits (Oryctolagus cuniculus) in Australia, linked to individual-based stochastic models and Bayesian approximations, to test whether (i) mortality associated with rabbit haemorrhagic disease (RHD) is driven primarily by seasonal matches/mismatches between demographic rates and epidemiological dynamics and (ii) delayed infection (arising from insusceptibility and maternal antibodies in juveniles) are important factors in determining disease severity and local population persistence of rabbits. We found that both the timing of reproduction and exposure to viruses drove recurrent seasonal epidemics of RHD. Protection conferred by insusceptibility and maternal antibodies controlled seasonal disease outbreaks by delaying infection; this could have also allowed escape from disease. The persistence of local populations was a stochastic outcome of recovery rates from both RHD and myxomatosis. If susceptibility to RHD is delayed, myxomatosis will have a pronounced effect on population extirpation when the two viruses coexist. This has important implications for wildlife management, because it is likely that such seasonal interplay and disease dynamics has a strong effect on long-term population viability for many species.


Subject(s)
Caliciviridae Infections/epidemiology , Caliciviridae Infections/immunology , Hemorrhagic Disease Virus, Rabbit/immunology , Introduced Species , Models, Immunological , Seasons , Animals , Australia/epidemiology , Female , Male , Myxomatosis, Infectious , Rabbits
16.
Mol Ecol ; 23(2): 408-20, 2014 Feb.
Article in English | MEDLINE | ID: mdl-24251353

ABSTRACT

Rabbit Haemorrhagic Disease Virus (RHDV) was introduced into Australia in 1995 as a biological control agent against the wild European rabbit (Oryctolagus cuniculus). We evaluated its evolution over a 16-year period (1995-2011) by examining 50 isolates collected throughout Australia, as well as the original inoculum strains. Phylogenetic analysis of capsid protein VP60 sequences of the Australian isolates, compared with those sampled globally, revealed that they form a monophyletic group with the inoculum strains (CAPM V-351 and RHDV351INOC). Strikingly, despite more than 3000 rereleases of RHDV351INOC since 1995, only a single viral lineage has sustained its transmission in the long-term, indicative of a major competitive advantage. In addition, we find evidence for widespread viral gene flow, in which multiple lineages entered individual geographic locations, resulting in a marked turnover of viral lineages with time, as well as a continual increase in viral genetic diversity. The rate of RHDV evolution recorded in Australia -4.0 (3.3-4.7) × 10(-3) nucleotide substitutions per site per year - was higher than previously observed in RHDV, and evidence for adaptive evolution was obtained at two VP60 residues. Finally, more intensive study of a single rabbit population (Turretfield) in South Australia provided no evidence for viral persistence between outbreaks, with genetic diversity instead generated by continual strain importation.


Subject(s)
Caliciviridae Infections/virology , Evolution, Molecular , Hemorrhagic Disease Virus, Rabbit/genetics , Viral Structural Proteins/genetics , Animals , Australia , Caliciviridae Infections/epidemiology , Caliciviridae Infections/veterinary , Gene Flow , Genetic Markers , Genetic Variation , Molecular Epidemiology , Molecular Sequence Data , Phylogeny , RNA, Viral/genetics , Rabbits , Sequence Analysis, DNA
17.
Evol Appl ; 7(9): 1056-67, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25553067

ABSTRACT

In Australia, the rabbit haemorrhagic disease virus (RHDV) has been used since 1996 to reduce numbers of introduced European rabbits (Oryctolagus cuniculus) which have a devastating impact on the native Australian environment. RHDV causes regular, short disease outbreaks, but little is known about how the virus persists and survives between epidemics. We examined the initial spread of RHDV to show that even upon its initial spread, the virus circulated continuously on a regional scale rather than persisting at a local population level and that Australian rabbit populations are highly interconnected by virus-carrying flying vectors. Sequencing data obtained from a single rabbit population showed that the viruses that caused an epidemic each year seldom bore close genetic resemblance to those present in previous years. Together, these data suggest that RHDV survives in the Australian environment through its ability to spread amongst rabbit subpopulations. This is consistent with modelling results that indicated that in a large interconnected rabbit meta-population, RHDV should maintain high virulence, cause short, strong disease outbreaks but show low persistence in any given subpopulation. This new epidemiological framework is important for understanding virus-host co-evolution and future disease management options of pest species to secure Australia's remaining natural biodiversity.

19.
Mol Ecol ; 21(5): 1038-41, 2012 Mar.
Article in English | MEDLINE | ID: mdl-22292800

ABSTRACT

Rabbit haemorrhagic disease virus (RHDV) is a highly virulent lagovirus endemic in Europe and Australasian populations of the European rabbit, Oryctolagus cuniculus. It has also caused several unexplained disease outbreaks in domestic European rabbits in North America. Non-pathogenic spread of RHDV leading to persistent infection which later reactivated has recently been proposed as the cause of overt disease and death of a pet rabbit in Canada, the first confirmed case of Rabbit haemorrhagic disease in that country. We suggest that there is little evidence to support non-pathogenic spread of virulent RHDV, some evidence that is contradictory, and evidence to support a simpler alternative hypothesis. RHDV can be spread over long distances between sparse rabbit populations by fomites or flying insects. Although highly pathogenic, RHDV can be limited in its spread within rabbit populations, or its presence masked by closely related but non-pathogenic lagoviruses which can provide protection against acute disease. In the absence of any evidence from clinical studies to support reactivation of persistent RHDV infection, the simpler explanation seems more likely to be correct.


Subject(s)
Caliciviridae Infections/transmission , Disease Outbreaks , Hemorrhagic Disease Virus, Rabbit/pathogenicity , Models, Biological , Animals , Australia/epidemiology , Caliciviridae Infections/epidemiology , Canada/epidemiology , Europe/epidemiology , Hemorrhagic Disease Virus, Rabbit/classification , Phylogeny , Rabbits
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