scholarly journals Retrospective studies on rabbit haemorrhagic disease outbreaks caused by RHDV GI.2 virus on farms in France from 2013 to 2018

2021 ◽  
Vol 29 (2) ◽  
pp. 87
Author(s):  
Adeline Huneau-Salaün ◽  
Samuel Boucher ◽  
Julie Fontaine ◽  
Bernadette Le Normand ◽  
Sébastien Lopez ◽  
...  
Keyword(s):  
Retrospective Studies ◽  
Disease Outbreaks ◽  
Epidemiological Studies ◽  
Structural Factors ◽  
Prevention Measures ◽  
Control Plan ◽  
Rabbit Haemorrhagic Disease ◽  
New Genotype ◽  
Haemorrhagic Disease ◽  
Control Study

Rabbit haemorrhagic disease (RHD) is a critical health threat to the rabbit industry in Europe. In 2018, the French rabbit industry adopted a voluntary control plan against this disease. In this context, two epidemiological studies were conducted on RHD outbreaks that occurred between 2013 and 2018 in France. The objectives were to describe the spread of RHD due to the new genotype RHDV GI.2 (rabbit haemorrhagic disease virus GI.2) and to identify rearing factors influencing the occurrence of the disease in order to guide the prevention measures recommended in the control plan. An analysis of cases on 295 farms between 2013 and 2017 showed that 32% of farms were affected at least once; the incidence of the disease increased in 2016-2017 compared to 2013-2015. Farms already affected in 2013-2015 had a higher risk of being infected in 2016-2017 than those that remained unaffected until 2015 (Relative Risk and 95% Confident Interval 1.7 [1.1-2.7]). A case-control study carried out between 2016 and 2018 on 37 outbreaks and 32 control farms revealed variability in biosecurity and decontamination practices between farms. The risk of being infected tends to be linked to these practices, but certain structural factors (e.g. the manure disposal system, transfer of rabbits at weaning) could also influence the risk of virus introduction into farms. In the context of a limited vaccination coverage of the farms (only females are vaccinated), these hypotheses will be studied further, using information from the RHD outbreak monitoring system implemented at the same time as the control plan in 2018.

scholarly journals Timing and severity of immunizing diseases in rabbits is controlled by seasonal matching of host and pathogen dynamics

2015 ◽  
Vol 12 (103) ◽  
pp. 20141184 ◽  
Author(s):  
Konstans Wells ◽  
Barry W. Brook ◽  
Robert C. Lacy ◽  
Greg J. Mutze ◽  
David E. Peacock ◽  
...  
Keyword(s):  
Local Population ◽  
Disease Outbreaks ◽  
Maternal Antibodies ◽  
Timing Of Reproduction ◽  
Demographic Rates ◽  
Pathogen Dynamics ◽  
Rabbit Haemorrhagic Disease ◽  
Seasonal Epidemics ◽  
Haemorrhagic Disease

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.

scholarly journals Novel Trivalent Vectored Vaccine for Control of Myxomatosis and Disease Caused by Classical and a New Genotype of Rabbit Haemorrhagic Disease Virus

Vaccines ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 441 ◽  
Author(s):  
Sylvia Reemers ◽  
Leon Peeters ◽  
Joyce van Schijndel ◽  
Beth Bruton ◽  
David Sutton ◽  
...  
Keyword(s):  
Disease Virus ◽  
Myxoma Virus ◽  
European Rabbit ◽  
Viral Diseases ◽  
Serological Response ◽  
Rabbit Haemorrhagic Disease Virus ◽  
Rabbit Haemorrhagic Disease ◽  
New Genotype ◽  
Vectored Vaccine ◽  
Haemorrhagic Disease

Myxoma virus (MV) and rabbit haemorrhagic disease virus (RHDV) are the major causes of lethal viral diseases in the European rabbit. In 2010, a new RHDV genotype (RHDV2) emerged in the field that had limited cross-protection with the classical RHDV (RHDV1). For optimal protection of rabbits and preventing spread of disease, a vaccine providing protection against all three key viruses would be ideal. Therefore, a novel trivalent myxoma vectored RHDV vaccine (Nobivac Myxo-RHD PLUS) was developed similar to the existing bivalent myxoma vectored RHDV vaccine Nobivac Myxo-RHD. The new vaccine contains the Myxo-RHDV1 strain already included in Nobivac Myxo-RHD and a similarly produced Myxo-RHDV2 strain. This paper describes several key safety and efficacy studies conducted for European licensing purposes. Nobivac Myxo-RHD PLUS showed to be safe for use in rabbits from five weeks of age onwards, including pregnant rabbits, and did not spread from vaccinated rabbits to in-contact controls. Furthermore, protection to RHDV1 and RHDV2 was demonstrated by challenge, while the serological response to MV was similar to that after vaccination with Nobivac Myxo-RHD. Therefore, routine vaccination with Nobivac Myxo-RHD PLUS can prevent the kept rabbit population from these major viral diseases.

Does a benign calicivirus reduce the effectiveness of rabbit haemorrhagic disease virus (RHDV) in Australia? Experimental evidence from field releases of RHDV on bait

2010 ◽  
Vol 37 (4) ◽  
pp. 311 ◽  
Author(s):  
Greg Mutze ◽  
Ron Sinclair ◽  
David Peacock ◽  
John Kovaliski ◽  
Lorenzo Capucci
Keyword(s):  
Disease Virus ◽  
Disease Outbreaks ◽  
Wild Rabbit ◽  
Rabbit Haemorrhagic Disease Virus ◽  
Agricultural Pests ◽  
Genetic Sequencing ◽  
Rabbit Haemorrhagic Disease ◽  
Almost All ◽  
Haemorrhagic Disease ◽  
The Impact

Context. European rabbits are serious environmental and agricultural pests throughout their range in Australia. Rabbit haemorrhagic disease virus (RHDV) greatly reduced rabbit numbers in arid central Australia but had less impact in cooler, higher-rainfall areas. RHDV-like benign caliciviruses (bCVs) have been implicated in limiting the impact of RHDV in the higher-rainfall regions of Australia and also in Europe. Aims. Experimental releases of RHDV on bait were tested as a means of initiating disease outbreaks. Serological evidence of antibodies to bCVs was examined to determine whether they reduce mortality rates and/or spread of the released RHDV, and how that might influence the effectiveness of future RHDV releases for rabbit management. Methods. Four experimental releases were conducted in high-rainfall and coastal regions of southern Australia. Virus activity was implied from recapture rates and serological changes in marked rabbits, and genetic sequencing of virus recovered from dead rabbits. Changes in rabbit abundance were estimated from spotlight transect counts. Key results. Release of RHDV on bait produced disease outbreaks that challenged almost all animals within the general release area and spread up to 4 km beyond the release sites. Recapture rates were high in marked rabbits that possessed antibodies from previous exposure to RHDV and extremely low amongst rabbits that lacked any detectable antibodies. Rabbits carrying antibodies classified as being due to previous infection with bCVs had recapture rates that were dependent on circulating antibody titre and were ~55% of recapture rates in rabbits with clear antibodies to RHDV. Conclusions. This is the first quantified evidence that antibodies produced against bCVs provide significant protection against RHD outbreaks in field populations of rabbits. Implications. bCVs can greatly reduce the impact of RHDV on wild-rabbit populations in Australia and presumably elsewhere. RHDV can be effectively released on bait although further releases are likely to be of minor or inconsistent benefit for controlling rabbit numbers where bCVs are common.

scholarly journals Retrospective serological analysis reveals presence of the emerging lagovirus RHDV2 in Australian wild rabbits at least six months prior to its first detection

2019 ◽  
Author(s):  
Tanja Strive ◽  
Melissa Piper ◽  
Nina Huang ◽  
Roslyn Mourant ◽  
John Kovaliski ◽  
...  
Keyword(s):  
Epidemiological Studies ◽  
Cross Reactivity ◽  
Monitoring Site ◽  
Wild Rabbit ◽  
Antibody Isotypes ◽  
Rabbit Haemorrhagic Disease ◽  
Different Types ◽  
Immunological Assays ◽  
Haemorrhagic Disease

SummaryThe lagovirus Rabbit Haemorrhagic Disease Virus (RHDV) has been circulating in Australia since the mid-1990s when it was deliberately released to control overabundant rabbit populations. In recent years, the viral diversity of different RHDVs in Australia has increased, and currently four different types of RHDV are known to be circulating. To allow for ongoing epidemiological studies and impact assessments of these viruses on Australian wild rabbit populations, it is essential that serological tools are updated. To this end, Reference sera were produced against all four virulent RHDVs (including RHDV2) known to be present in Australia and tested in a series of available immunological assays originally developed for the prototype RHDV, to assess patterns of cross reactivity and the usefulness of these assays to detect lagovirus antibodies, either in a generic or specific manner. Enzyme Linked Immuno Sorbent Assays (ELISAs) developed to detect antibody isotypes IgM, IgA and IgG were sufficiently cross reactive to detect antibodies raised against all four virulent lagoviruses. For the more specific detection of antibodies to the antigenically more different RHDV2, a competition ELISA was adapted using RHDV2 specific monoclonal antibodies in combination with Australian viral antigen. Archival serum banks from a long term rabbit monitoring site where rabbits were sampled quarterly over a period of six years were re-screened using this assay, and revealed serological evidence for the arrival of RHDV2 in this population at least six months prior to its initial detection in Australia in a deceased rabbit in May 2015. The serological methods and reference reagents described here will provide valuable tools to study presence, prevalence and impact of RHDV2 on Australian rabbit populations; however the discrimination of different antigenic variants of RHDVs as well as mixed infections at the serological level remains challenging.

Serological evidence for the presence of a calicivirus in Australian wild rabbits, Oryctolagus cuniculus, before the introduction of rabbit haemorrhagic disease virus (RHDV): its potential influence on the specificity of a competitive ELISA for RHDV

2002 ◽  
Vol 29 (6) ◽  
pp. 655 ◽  
Author(s):  
A. J. Robinson ◽  
P. D. Kirkland ◽  
R. I. Forrester ◽  
L. Capucci ◽  
B. D. Cooke ◽  
...  
Keyword(s):  
Solid Phase ◽  
Epidemiological Studies ◽  
Enzyme Linked Immunosorbent Assay ◽  
European Brown Hare ◽  
Wild Stock ◽  
Rabbit Haemorrhagic Disease ◽  
European Brown Hare Syndrome ◽  
Animal House ◽  
Haemorrhagic Disease ◽  
Positive Results

The objective of the study was to determine for Australian wild rabbits the specificity of a competitive enzyme-linked immunosorbent assay (cELISA) developed in Italy for detecting antibodies to RHDV. Analysis of 657 sera collected before the arrival of RHDV (pre-RHD) indicated that between 17 and 38% appeared to give false positive results depending on the cut-off criteria used. The finding of pre-RHD sera reacting positively in the cELISA prompted the testing of sera in a cELISA using as antigen smooth forms of RHDV (cELISA-sf) and a solid-phase ELISA (spELISA), both of which detect reactivity to an epitope shared by the lagomorph caliciviruses. Testing of a subset of the pre-RHD sera in the cELISA-sf and the spELISA revealed that 86 and 91%, respectively, were positive. Similar results were obtained for a set of sera collected pre-RHD in the Australian Capital Territory (ACT). Sera collected from wild-stock rabbits born and raised in isolation in an animal house in the ACT were all negative in the cELISA, 6% were positive in the cELISA-sf and 13% in the spELISA. It was concluded that a calicivirus related to RHDV and European brown hare syndrome virus (EBHSV) was present in the rabbit population before the arrival of RHDV, and may still be present. The potential consequences of these findings for epidemiological studies on RHD in Australia are discussed.

Family-, Media-, and School-Related Risk Factors of Video Game Addiction

2013 ◽  
Vol 25 (3) ◽  
pp. 118-128 ◽  
Author(s):  
Florian Rehbein ◽  
Dirk Baier
Keyword(s):  
Risk Factors ◽  
Video Game ◽  
Age Groups ◽  
Well Being ◽  
Epidemiological Studies ◽  
Prevention Measures ◽  
School Life ◽  
Video Game Addiction ◽  
Effective Prevention ◽  
Game Addiction

In recent years, a variety of epidemiological studies have provided empirical data on the prevalence of video game addiction (GA) in different age groups. However, few studies investigated the causes of GA and could explain why video game playing as a widespread phenomenon leads to a comparatively small percentage of addicted players. Additionally, the existing longitudinal studies mainly consider psychological trait variables and neglect the possible explanatory value of predictors in socialization regarding media availability, media use, and family and everyday school life. In this paper, the results of a two-wave longitudinal study comprising a sample of students from Grades 4 to 9 (N = 406) are presented. The data show that 15-year-old video game addicts had already exhibited a number of specific risk factors at the age of 10. Students from single-parent families seem to be particularly at risk, as are students with low experienced school well-being and with a weaker social integration in class. The data also indicate that problematic use of video games in childhood increases the risk of GA in adolescence. Male students are especially vulnerable for developing GA. The results of this study are an important contribution to understanding risk factors for GA in adolescents, thereby laying the groundwork for effective prevention measures.

scholarly journals Microbial metagenomic approach uncovers the first rabbit haemorrhagic disease virus genome in Sub-Saharan Africa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anise N. Happi ◽  
Olusola A. Ogunsanya ◽  
Judith U. Oguzie ◽  
Paul E. Oluniyi ◽  
Alhaji S. Olono ◽  
...  
Keyword(s):  
Virus Genome ◽  
Sub Saharan Africa ◽  
High Morbidity ◽  
Vp60 Gene ◽  
Band Size ◽  
Rabbit Haemorrhagic Disease ◽  
Sub Saharan ◽  
Domestic Rabbits ◽  
Haemorrhagic Disease ◽  
Pcr Targeting

AbstractRabbit Haemorrhagic Disease (RHD) causes high morbidity and mortality in rabbits and hares. Here, we report the first genomic characterization of lagovirus GI.2 virus in domestic rabbits from sub-Saharan Africa. We used an unbiased microbial metagenomic Next Generation Sequencing (mNGS) approach to diagnose the pathogen causing the suspected outbreak of RHD in Ibadan, Nigeria. The liver, spleen, and lung samples of five rabbits from an outbreak in 2 farms were analyzed. The mNGS revealed one full and two partial RHDV2 genomes on both farms. Phylogenetic analysis showed close clustering with RHDV2 lineages from Europe (98.6% similarity with RHDV2 in the Netherlands, and 99.1 to 100% identity with RHDV2 in Germany), suggesting potential importation. Subsequently, all the samples were confirmed by RHDV virus-specific RT-PCR targeting the VP60 gene with the expected band size of 398 bp for the five rabbits sampled. Our findings highlight the need for increased genomic surveillance of RHDV2 to track its origin, understand its diversity and to inform public health policy in Nigeria, and Sub-Saharan Africa.

Habitat factors related to wild rabbit population trends after the initial impact of rabbit haemorrhagic disease

2006 ◽  
Vol 33 (6) ◽  
pp. 467 ◽  
Author(s):  
Carlos Calvete ◽  
Enrique Pelayo ◽  
Javier Sampietro
Keyword(s):  
Habitat Quality ◽  
Population Trends ◽  
Wild Rabbit ◽  
Pest Species ◽  
Predator Species ◽  
Rabbit Population ◽  
Habitat Factors ◽  
Rabbit Haemorrhagic Disease ◽  
Haemorrhagic Disease

The European wild rabbit (Oryctolagus cuniculus) is an introduced pest species in Australia and New Zealand. Rabbits have a devastating negative impact on agricultural production and biodiversity in these countries, and Rabbit Haemorrhagic Disease (RHD) is currently included in control strategies for rabbit populations. On the other hand, the European wild rabbit is a key native prey species in the Iberian Peninsula. Since the arrival of RHD, however, rabbit populations have undergone dramatic decreases and several predator species at risk of extinction are currently dependent on the rabbit population density. Therefore, from the point of view of biodiversity conservation, evaluating habitat correlates and trends of rabbit populations after the first RHD epizootic is of great interest to improve the long-term control or promotion of wild rabbit populations. We estimated the relationship between habitat factors and long-term population trends as well as the relationships between habitat factors and rabbit abundance 2 and 14 years after the arrival of RHD in several Iberian rabbit populations. We observed that only 26% of surveyed populations seemed to experience an increase in rabbit abundance over the last 12 years and that this increase was higher in the low-rabbit-abundance areas of l992, leading to high rabbit abundance in 2004. Our results suggested that short- and long-term impacts of RHD were related to habitat quality. The initial impact of RHD was higher in more suitable habitats, but increasing long-term population trends were positively related to good habitat quality.

scholarly journals The emergence of rabbit haemorrhagic disease virus: will a non-pathogenic strain protect the UK?

2001 ◽  
Vol 356 (1411) ◽  
pp. 1087-1095 ◽  
Author(s):  
P.J. White ◽  
R.A. Norman ◽  
R.C. Trout ◽  
E.A. Gould ◽  
P.J. Hudson
Keyword(s):  
Disease Virus ◽  
Pathogenic Strain ◽  
Rabbit Haemorrhagic Disease Virus ◽  
Rabbit Haemorrhagic Disease ◽  
Seroprevalence Data ◽  
Age Structured ◽  
Reproductive Rates ◽  
The Uk ◽  
Haemorrhagic Disease ◽  
Age Structured Model

Rabbit haemorrhagic disease virus emerged in China in 1984, and has killed hundreds of millions of wild rabbits in Australia and Europe. In the UK there appears to be an endemic non–pathogenic strain, with high levels of seroprevalence being recorded, in the absence of associated mortality. Using a seasonal, age–structured model we examine the hypothesis that differences in rabbit population demography differentially affect the basic reproductive rates ( R 0 ) of the pathogenic and non–pathogenic strains, leading to each dominating in some populations and not others. The strain with the higher R 0 excluded the other, with the dynamics depending upon the ratio of the two R 0 values. When the non–pathogenic strain dominated, the pathogenic strain caused only transient mortality, although this could be significant when the two R 0 values were similar. When the pathogenic strain dominated, repeated epidemics led to host eradication. Seroprevalence data suggest that the non–pathogenic strain may be protecting some, but not all UK populations, with half being ‘at risk’ from invasion by the pathogenic strain and a fifth prone to significant transient mortality. We identify key questions for empirical research to test this prediction.

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