Register      Login
Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats
RESEARCH ARTICLE

The reintroduction, and subsequent impact, of rabbit haemorrhagic disease virus in a population of wild rabbits in south-western Australia

John S. Bruce A and Laurie E. Twigg B C
+ Author Affiliations
- Author Affiliations

A Protection Services, Department of Agriculture, Western Australia, 444 Albany Highway, Albany, WA 6330, Australia.

B Vertebrate Pest Research Section, Department of Agriculture, Western Australia, 100 Bougainvillea Avenue, Forrestfield, WA 6058, Australia.

C Corresponding author. Email: ltwigg@agric.wa.gov.au

Wildlife Research 32(2) 139-150 https://doi.org/10.1071/WR04025
Submitted: 13 April 2004  Accepted: 21 December 2004   Published: 4 May 2005

Abstract

The natural arrival of rabbit haemorrhagic disease virus (RHDV) in south-western Australia in September 1996 resulted in a reduction in rabbit numbers of ~65% (~90% morbidity, with ~72% mortality of infected rabbits). As no signs of the disease (clinical or serological) were seen over the next two years, and as rabbit numbers over the last 12-month monitoring period at the site were similar to those observed before the natural 1996 RHDV epizootic (i.e. pre-RHD), RHDV was deliberately reintroduced into this rabbit population in April 1999 (autumn). Seven RHDV-inoculated rabbits were released prior to the main breeding season when <3% of sampled rabbits (n = 118) were seropositive for RHDV antibodies. Following the deliberate release, the overall decline in rabbit numbers (68%) was comparable to that seen during the natural 1996 epizootic. However, on the basis of the observed changes in rabbit numbers, and in their serology, the impact of the deliberate RHDV release appeared to be more variable across the six trapping areas than was seen during the natural 1996 spring epizootic. The reductions in rabbit numbers on these areas 6–8 weeks after RHDV-release ranged from 55% to 90%. The serology of the surviving rabbits on the trapping areas was also variable over this period, with the proportion of seropositive rabbits ranging from 5% to 90%. Overall, only 15% of the surviving rabbit population showed evidence of recent challenge by RHDV, giving a morbidity rate of 73% 8 weeks after the release. However, over 90% of infected rabbits died. This provides further evidence that some rabbits remained un-challenged by RHDV for up to 8 weeks after its release. The variable impact of the April 1999 release may have been partially caused by the observed differences in abundance of insect vectors, and/or an apparent increase in the incidence of non-virulent RHDV in the months preceding the release.


Acknowledgments

This work was undertaken with joint funding from the Australian National RHD Scientific Program, and the Department of Agriculture, Western Australia. The project was instigated by Dr Tony Henson and John Bruce, and completed by John Bruce and Laurie Twigg, and we thank Tony for his input. We also thank Hadn and Jann Hood, and John and Dorothy Hood for access to their property. Most of the assays were outsourced to John Parkinson (DAWA) and John Kovaliski (APCC, SA). We thank all our colleagues, and the anonymous referees, for their helpful discussions and comments in improving the paper. All animals were handled in accordance with the Western Australian Department of Agriculture’s (Australian) Code of Practice for Animal Experimentation.


References

Asgari, S. , Hardy, J. R. E. , Sinclair, R. G. , and Cooke, B. D. (1998). Field evidence of mechanical transmission of rabbit haemorrhagic disease virus (RHDV) by flies (Diptera: Calliphoridae) among wild rabbits in Australia. Virus Research 54, 123–132.
Crossref | GoogleScholarGoogle Scholar | PubMed | Calvete C., and Estrada R. (2000). Epidemiologia de enfermedad hemorragica (VHD) y mixomatosis en el conejo sylvestre en el valle medio del Ebro. Heramientas de gestion. Consejo de la Proteccion de la Naturaleza de Aragon. ARPI relieve, SA.

Capucci, L. , Fusi, P. , Lavazza, A. , Pacciarini, M. L. , and Rossi, C. (1996). Detection and preliminary characterisation of a new rabbit calicivirus related to rabbit haemorrhagic disease virus but non-pathogenic. Journal of Virology 70, 8614–8623.
PubMed | Fenner F., and Ratcliffe F. N. (1965). ‘Myxomatosis.’ (Cambridge University Press: Cambridge.)

Fuller, H. E. , Chasey, D. , Lucas, M. H. , and Gibbens, J. C. (1993). Rabbit haemorrhagic disease in the United Kingdom. Veterinary Record 133, 611–613.
PubMed | Lenghaus C., Westbury H., Collins B., Ratnamoban N., and Morrissy C. (1994). Overview of the RHD project in the Australian Animal Health Laboratory. In ‘Rabbit Haemorrhagic Disease: Issues in Assessment for Biological Control’. (Eds R. K. Munro and R. T. Williams.) (Bureau of Resource Sciences, Australian Government Printing Service: Canberra.)

Lugton, I. W. (1999). A cross-sectional study of risk factors affecting the outcome of rabbit haemorrhagic disease virus releases in New South Wales. Australian Veterinary Journal 77, 322–328.
PubMed | Neave H. M. (1999). ‘Rabbit Calicivirus Disease Report Program 1: Overview of Effects on Australian Wild Rabbit Populations and Implications for Agriculture and Biodiversity.’ (Bureau of Resource Sciences & Australian Government Printing Service: Canberra.)

O’Keefe, J. S. , Tempero, J. E. , Motha, M. X. , Hansen, M. F. , and Atkinson, P. H. (1999). Serology of rabbit haemorrhagic disease before and after release of the virus in New Zealand. Veterinary Microbiology 66, 29–40.
Crossref | GoogleScholarGoogle Scholar | PubMed | Richardson B. J. (2001). Calicivirus, myxoma virus and the wild rabbit in Australia: a tale of three invasions. In ‘Proceedings of SGM Symposium 60: New Challenges to Health: The Threat of Virus Infection’. (Eds G. L. Smith, W. L. Irving, J. W. McCauley and D. J. Rowlands.) pp. 67–87. (Cambridge University Press: Cambridge.)

Robinson, A. J. , Kirkland, P. D. , Forrester, R. I. , Capucci, L. , Cooke, B. D. , and Philbey, A. W. (2002a). Serological evidence for the presence of a calicivirus in Australian wild rabbits Oryctolagus cuniculus prior to the introduction of rabbit haemorrhagic disease virus (RHDV) and its potential influence on the specificity of a cELISA for RHDV. Wildlife Research 29, 655–662.
Smyth R. E., Cooke B. D., and Newsome A. E. (1997). The spread of rabbit calicivirus in relation to environmental factors. CSIRO Wildlife and Ecology, Australia.

Twigg, L. E. , Griffin, S. L. , and O’Reilly, C. M. (1996). Techniques for live capture of the European rabbit (Oryctolagus cuniculus). Western Australian Naturalist 21, 131–140.
Westbury H. (1996). Field evaluation of RCD under quarantine. Final report of project CS236, Meat Research Corporation, Sydney.

White, P. C. , Newton-Cross, G. A. , Gray, M. , Ashford, R. , White, C. , and Saunders, G. (2003). Spatial interactions and habitat use of rabbits on pasture and implications for the spread of rabbit haemorrhagic disease in New South Wales. Wildlife Research 30, 49–58.
Crossref | GoogleScholarGoogle Scholar |