Assessment of the risk of inadvertently exporting from Australia a genetically modified immunocontraceptive virus in live mice (Mus musculus domesticus)
C. K. WilliamsCSIRO Sustainable Ecosystems, and Pest Animal Control Cooperative Research Centre, GPO Box 284, Canberra, ACT 2601, Australia. Present address: 9 Macleay Street, Turner, ACT 2612, Australia.
Wildlife Research 34(7) 540-554 https://doi.org/10.1071/WR05028
Submitted: 7 March 2005 Accepted: 12 December 2006 Published: 13 December 2007
Abstract
Controlling mouse plagues in the Australian grain-growing regions using a proposed species-specific, genetically modified, immunocontraceptive (IC) murine cytomegalovirus (icMCMV) may risk infected mice infesting export cargo and, subsequently in other countries, infecting closely related, susceptible and valued Mus species. This paper uses simple simulation models to examine (a) how design of an IC virus and deployment strategy could affect the likelihood of inadvertent export, and (b) where intervention may minimise the likelihood of export effectively and economically. Field efficacy is best in an IC virus with an immunocontraceptive efficacy of 75–100% and high transmissibility, and the likelihood of export is lower than for some less efficacious designs. Greatest likelihood of export arises from using an IC virus with low (or zero) immunocontraceptive efficacy and high transmissibility. Lower transmissibility of the IC virus relative to field strains reduces field efficacy and the likelihood of export. Conversely, higher relative transmissibility increases field efficacy and modestly increases the likelihood of export. Effective control of mice in the field requires the IC virus to infect a high proportion of the mouse population while numbers are very low. Deviation from this strategy through (a) underestimation of mouse abundance, and (b) late deployment during population increase, diminishes effectiveness in the field and increases the likelihood of export. Intervention at ports seems the most effective strategy to mitigate export risk. Australian legislation and codes of practice specify export quarantine procedures for particular types of goods but are silent for others. Current practices for shipping container movements also leave gaps in the export quarantine barrier.
Acknowledgements
I thank David Ryan and David Heinrich (formerly) of Australian Quarantine and Inspection Service, Canberra, for advice on quarantine matters, and Grant Singleton, Chris Hardy, Tony Arthur, Lyn Hinds and David Dall for critical comment on earlier drafts of the manuscript. I am grateful to a referee, Henrik Moller, University of Otago, for useful comment.
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