School of BioSciences - Research Publications

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    Using decision support tools in emergency animal disease planning and response: Foot and mouth disease (CEBRA Project 1404D), Technical Report prepared for the Department of Agriculture and Water Resources
    Garner, G ; East, I ; Bradhurst, R ; Roche, S ; Rawdon, T ; Sanson, R ; Kompas, T ; Van Pham, H ; Stevenson, M (University of Melbourne, 2016)
    Modelling studies both in Australia and overseas have shown that vaccination can be very effective in reducing the size and duration of an FMD outbreak. Vaccination is most effective in reducing the duration and size of an outbreak when used early and is less effective the longer you delay. However, a decision to vaccinate early in the outbreak may result in using vaccination in situations where it is not actually required, with consequent implications for post-outbreak surveillance, the management of vaccinated animals and the ability to regain FMD-free status and access to markets. Overall, the choice of control measure to adopt in an FMD outbreak will thus depend on the variable and potentially conflicting objectives of the control program. As an important component of disease planning and preparedness for the department, the project will report on key information that could be used in an FMD outbreak to infer the potential scale of an outbreak and information to support disease management decision-making.
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    Incorporating economic components in Australia's FMD modelling capability and evaluating post-outbreak management to support return to trade (CEBRA project 1608D), Technical Report for the Department of Agriculture, Water and Environment
    Garner, G ; Bradhurst, R ; Death, C ; Dodd, A ; East, I ; Kompas, T (University of Melbourne, 2017)
    Following an outbreak of FMD, surveillance will be required to demonstrate that infection has been eradicated from the population and enable any remaining movement restrictions to be lifted within the country. Proof of freedom will also be needed to satisfy trading partners and regain access to international markets. Although vaccination is increasingly being recognised as an important tool to assist in containing and eradicating FMD outbreaks, it will make achieving recognition of free status more difficult—keeping vaccinated animals in the population will delay the period until FMD-free status is regained under the World Organisation for Animal Health (OIE) guidelines and add additional complications to the postoutbreak surveillance program. There is no agreed approach to post-outbreak management of vaccinated animals in AUSVETPLAN with the options being to: (1) allow vaccinated animals to remain in the population to live out their normal commercial lives (vaccinate-to-live); (2) remove all vaccinated animals from the population (vaccinateand- remove). Under option 2, vaccinated animals could be subject to (a) slaughter to waste i.e. remove and dispose of vaccinated animals; or (b) slaughter and salvage i.e. attempt to sell either raw or processed product from vaccinated animals. For (b) there may be some residual value of products that could offset some of the costs. The project will bring together epidemiological and economic expertise from the Department, the Australian National University, and CEBRA to formally explore and establish a science-based and cost effective approach to regaining free-status after an FMD outbreak as expeditiously as possible. The project will expand the Department’s modelling capability as well as providing insights into postoutbreak FMD management and contribute to Australia’s FMD preparedness.
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    National-level farm demographic data for preparedness of highly-infectious livestock disease epidemics. Review of data sources in New Zealand, approach to modelling populations and the effect of population uncertainty on disease modelling.
    van Andel, M ; Hollings, T ; Robinson, A ; Jewell, C ; Burgman, M ; Vink, D ; Sattler, K ; Masako, W ; Carpenter, T ; Bradhurst, R ; Garner, G (University of Melbourne, 2016)
    Isolation and strict biosecurity measures implemented by Australia and New Zealand have prevented the incursion of many organisms of biosecurity concern. The agricultural industry is a key part of the economy for both countries, and preventing the arrival of diseases of concern, including foot-and-mouth (FMD) disease, is crucial to maintaining access to international markets, reputation, and protecting the economy and industry. Early detection of, and a rapid, effective response to such diseases have a large impact on limiting the economic damage caused by epidemics. An acknowledged weakness of biosecurity preparedness and response to agricultural diseases in both countries is the lack of a single source of accurate, up-to-date farm livestock demographics information. This report reviews the use of animal counts for investigation of, preparedness for and response to exotic animal disease outbreaks, and analyses the available New Zealand datasets in depth. Gaps and weaknesses in the current data landscape are documented. The project objectives then focus on developing methodologies to estimate national-level farm demographic data and assess the use of modelled and inaccurate data in disease simulation models. There are nine key deliverables outlined in the report which were carried out over the two year duration of the project.
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    Cost-benefit analysis of the yellow crazy ant eradication program. Technical Report prepared for the Wet Tropics Management Authority
    Spring, D ; Kompas, T ; Bradhurst, R (Centre of Excellence for Biosecurity Risk Analysis, 2019)
    Yellow crazy ants (Anoplolepis gracilipes) (YCA) are one of the world’s 100 worst invasive species (Lowe et al. 2000). Previous assessments of YCA invasions have demonstrated that YCA can dramatically reduce native species richness in invaded areas, including in the Seychelles (Bos et al. 2008), Christmas Island (O'Dowd et al. 2003), and Hawaii (Plentovich et al. 2011). Native species losses include direct losses of competing invertebrate species and indirect losses resulting from ecological interdependencies, which can result in “ecological meltdown” in extreme cases such as Christmas Island (O'Dowd et al. 2003). YCA can also cause large losses to people living in infested areas through nuisance and health effects (Lach and Hoskin 2015) and can also adversely affect agricultural producers (Young et al. 2001) through reducing yields and/or increasing pesticide costs. YCA was first detected in Cairns and its southern suburbs in 2001, and an eradication program was initiated by the Department of Natural Resources and Mines (DNRM) and Biosecurity Queensland as part of a larger state-wide program. Later discoveries of YCA across the state, including in and around the WTWHA led to the state-wide eradication program being discontinued. An application was then made by WTMA to continue eradication efforts in and around the WTWHA. The program has been funded by the Australian Government and the Queensland Government in two overlapping projects, as described in the Executive Summary.
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    Modelling post-border spread and control of African swine fever on a national scale (Biosecurity Innovation Program Project 182021). Technical report prepared for the Department of Agriculture, Fisheries & Forestry
    Bradhurst, R ; Garner, G ; Richards, K ; Willis, S ; Taha, H ; Sellens, E ; Naing, L ; Cowled, B ; Roche, S (University of Melbourne, 2022)
    African swine fever (ASF) represents a significant threat to the Australian pork sector and the economy in general. Estimates of the economic damages from a large multistate outbreak of ASF in Australia exceed $A2 billion. ASF outbreaks are widespread and increasing in number in Asia and Europe. Although ASF is not present in Australia, detections of ASF viral fragments in undeclared pork products intercepted at the Australian border and the recent spread of the disease to neighbouring Papua New Guinea demonstrate the significance of the threat. The AADIS-ASF model (Bradhurst et al., 2021c), simulates the spread and control of ASF in domestic and feral pigs. It was developed through Biosecurity Innovation Project 192027 and CEBRA project 20121501, with Queensland as the test case. This project expanded the AADIS-ASF model up to national scale. The upgraded model will help evaluate different outbreak scenarios in time and space, and trial various control measures. This will assist in the development of animal health policy and preparedness and planning for ASF outbreaks.
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    Development and outputs of an epidemiological model to assess the sensitivity of the New Zealand background surveillance system for Mycoplasma bovis
    Bradhurst, R ; Burroughs, A ; Crosbie, A ; Firestone, S ; Stevenson, M ; Robinson, A (University of Melbourne, 2022)
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    Analysis of livestock movements and the benefits and costs of livestock standstills in Australia as part of the response to foot and-mouth disease
    Seitzinger, A ; Garner, G ; Bradhurst, R ; Okelo, W (CSIRO, 2022)
    This project involved analysis of livestock movements and used epidemiological modelling and cost analysis to estimate the benefits and costs of implementing livestock standstills in response to a foot-and-mouth disease (FMD) outbreak in Australia. This was done in four steps: 1) assessing the extent of livestock movement, 2) conducting a cross sectional analysis of the impact (reduction of outbreak size and economic cost) of implementing a national standstill/movement control, 3) use of case specific studies to estimate impact of state/territory level implementation of standstill, and 4) cost analysis and comparison of national standstill with the state/jurisdictional level and risk-based approach strategies. Estimation of the extent of livestock movement within and between jurisdictions was done using the 2019 (calendar year) Australian National Livestock Identification System (NLIS) data, i.e., prior to the COVID 19 pandemic, for cattle, sheep and goats and pigs. Estimation of the epidemiological and economic impact of implementing standstill to control FMD at the national and state levels was done using the Australian Animal Disease Spread (AADIS). To test the hypothesis that a national livestock standstill is effective in reducing spread of infection, a wide range of potential FMD incursions (n=10,000) was used and the actual numbers of infected herds in the population were compared after 7 days of control, with and without a 3-day national livestock standstill. Additionally, five detailed outbreak incursion scenarios, developed in consultation with jurisdictions or based on previous national modelling scenarios, were also simulated. These were biased to larger multi-jurisdictional outbreaks aimed at showing any potential benefits of livestock standstills in reducing the size and duration of the ensuing outbreaks. National 3- and 10-day livestock standstills were compared with other standstills involving the infected jurisdiction(s) only, or regional standstills (infected and adjacent jurisdictions). Cost analysis involved identifying components associated with implementing and managing livestock standstills. This included analysis of three approaches to managing livestock in transit: (a) livestock in transit continuing the movement to their initially intended destination (Proceed to Destination); (b) a risk assessed option (Mixed option) which considered type of property of origin and destination, whether involving single/multiple consignments on transport vehicles and distances travelled; and (c) a third option of redirecting all livestock in transit to abattoir (Redirect to Slaughter). The key finding of this study include: • The average number of animals (all referenced species) moved per day was 237,000 (range 1,000 – 533,000) of which 76.9% were intrastate and 23.1% were interstate movements (Table 1) with majority destined for processing. • Although interstate movement of livestock was relatively low compared to intrastate movements, it was still an important component of livestock production systems in Australia. • In simulated FMD outbreaks it was not uncommon for interstate spread of infection to occur, given three to four weeks until disease is detected, particularly for outbreaks starting in south-eastern Australia. • No consistent benefit of 3- or 10-day national standstills over state/territory wide based standstill/movement controls, in terms of reducing the size of a potential FMD outbreak in Australia was demonstrated. • Implementation of 3-day national livestock standstill was estimated to cost up to $75.6 million when animals not initially intended for processing abattoir were primarily directed to abattoirs (i.e., Redirect to Slaughter). • The cost of implementation of a risk assessed option (Mixed option), was approximately to be $50 million on the upper range value. • The option for livestock in transit to Proceed to Destination provided the minimum cost of implementing a standstill, ranging between $0.4 million and $3.6 million. Factors contributing to national livestock standstill disease control benefits not being demonstrated include that a significant proportion of inter-jurisdictional movements involve movements to a terminal destination. In simulated outbreaks, spread of infection by livestock movements accounted for a relatively small proportion of all infections. Most new infections result from ‘local’ spread i.e. short-range transmission of disease from an infected herd to neighbouring susceptible herds. Local spread is recognised as an important pathway for FMD, particular in high-density farming areas. Once disease has been detected and state/territory wide control measures implemented in infected jurisdictions, livestock movements are further reduced. Another important factor is the behaviour of livestock producers/industry in non-infected jurisdictions in response to the changed market conditions subsequent to a detection of FMD. The suspension of access to export markets for susceptible livestock and livestock products and concerns about biosecurity means it is not ‘business as usual’. This was modelled by a 50% reduction in the number of ‘normal’ movements expected to occur. There may be ancillary benefits to a national livestock standstill in terms of information for trading partners and international organizations regarding the comprehensiveness of Analysis of livestock movements and the benefits and costs of livestock standstills in Australia as part of the response to foot-and-mouth disease. Australia’s approach to managing the outbreak, perhaps translating into increased confidence and willingness to negotiate the re-establishment of market access more rapidly. Assumptions were necessarily included in this study, which included: • The NLIS data was an accurate representation of livestock movements. It is important to note that AADIS cannot model/account for movement of livestock between properties under the same property identification code, given these do not need to be recorded within NLIS. Whilst these movements may be local/regional, the actual level of movement will be greater than that analysed as part of this project. • Vaccination was not used and ‘stamping out’ occurred for each of the modelled outbreaks. • Reporting of suspect cases, surveillance and tracing were highly effective. • No disease spread resulted from in-transit animals returning to their origin (multi-consignment/property transport was not modelled to return to property of origin). • The 3-day national livestock standstill did not cause significant loss of livestock or product quality or involve additional capital investment for implementing the standstill. • Reduced value of livestock and product was not attributed to the standstill but instead considered to result from the immediate suspension of export market access following the detection of FMD. • The modelling assumed that disease reporting, tracing and surveillance were all conducted in a highly effective manner, based on previous experience and estimated performance of tracing systems. National livestock standstills may provide more benefit in situations where response measures are not as effective as assumed. In conclusion, this study did not demonstrate that a national standstill on livestock movements, for 3 days or 10 days, was effective in reducing the size or duration of an FMD outbreak in Australia compared to state-based restrictions. The estimated high cost of a national standstill if implemented in accordance with the current National Agreed Standard Operating Procedure for livestock in transit at the time of declaration of a national livestock standstill is a further consideration. Although this study did not show a clear benefit, it is possible that a national livestock standstill may be effective under very specific circumstances i.e., in multi-state outbreaks where there have been large numbers of animal movements. Risk-based implementation of state/territory wide livestock standstills by jurisdictions upon detection or strong suspicion of FMD may be a viable alternative policy rather than a mandatory national livestock standstill implemented automatically on strong suspicion or detection of FMD in any state/territory. This risk management should take into account location of the outbreak, industry sectors involved, time of year and any information on extent and destination of livestock movements. Further, where standstills are applied, management of livestock in transit, could be on a risk assessed basis taking into account type of property of origin and destination, single/multiple transport and distances travelled.
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    Modelling the spread and control of African swine fever in domestic and feral pigs
    Bradhurst, R ; Garner, G ; Roche, S ; Iglesias, R ; Kung, N ; Robinson, B ; Willis, S ; Cozens, M ; Richards, K ; Cowled, B ; Oberin, M ; Tharle, C ; Firestone, S ; Stevenson, M (University of Melbourne, 2021)
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    Vector-borne spread of Animal Disease (CEBRA Project 1608B). Technical Report for the Department of Agriculture, Water and Environment
    Bradhurst, R ; Garner, G ; East, I ; Iglesias, R ; Stevenson, M ; AL-RIYAMI, S ; Kompas, T (University of Melbourne, 2018)
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