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    Post-outbreak surveillance strategies to support proof of freedom from foot-and-mouth disease
    Bradhurst, R ; Garner, G ; East, I ; Death, C ; Dodd, A ; Kompas, T ( 2021-04-28)
    Abstract Whilst emergency vaccination may help contain foot-and-mouth disease in a previously FMD-free country, its use complicates post-outbreak surveillance and the recovery of FMD-free status. A structured surveillance program is required that can distinguish between vaccinated and residually infected animals, and provide statistical confidence that the virus is no longer circulating in previously infected areas. Epidemiological models have been well-used to investigate the potential benefits of emergency vaccination during a control progam and when/where/whom to vaccinate in the face of finite supplies of vaccine and personnel. Less well studied are post-outbreak issues such as the management of vaccinated animals and the implications of having used vaccination during surveillance regimes to support proof-of-freedom. This paper presents enhancements to the Australian Animal Disease Model (AADIS) that allow comparisons of different post-outbreak surveillance sampling regimes for establishing proof-of-freedom from FMD. A case study is provided that compares a baseline surveillance sampling regime (derived from current OIE guidelines), with an alternative less intensive sampling regime. It was found that when vaccination was not part of the control program, a reduced sampling intensity significantly reduced the number of samples collected and the cost of the post-outbreak surveillance program, without increasing the risk of missing residual infected herds.
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    Reallocating budgets among ongoing and emerging conservation projects
    Wu, C-H ; Dodd, AJ ; Hauser, CE ; McCarthy, MA (WILEY, 2021-06)
    Conserving biodiversity and combating ecological hazards require cost-effective allocation of limited resources among potential management projects. Project priorities, however, can change over time as underlying social-ecological systems progress, novel priorities emerge, and management capabilities evolve. Thus, reallocation of ongoing investments in response to shifting priorities could improve management outcomes and address urgent demands, especially when additional funding is not available immediately. Resource reallocation, however, could incur transaction costs, require additional monitoring and reassessment, and be constrained by ongoing project commitments. Such complexities may prevent managers from considering potentially beneficial reallocation strategies, reducing long-term effectiveness. We propose an iterative project prioritization approach, based on marginal return-on-investment estimation and portfolio optimization, that guides resource reallocation among ongoing and new projects. Using simulation experiments in 2 case studies, we explored how this approach can improve efficacy under varying reallocation constraints, frequencies, costs, and rates of project portfolio change. Periodic budget reallocation could enhance the management of stochastically emerging invasive weeds in Australia and thus reduce the overall risk by up to 50% compared with a static budget. Reallocation frequency and the rate of new weed incursion synergistically increased the conservation gains achieved by allowing unconstrained reallocation. Conversely, budget reallocation would not improve the International Union for Conservation of Nature conservation status of threatened Australian birds due to slow rates of transition among conservation states; extinction risk could increase if portfolio reassessment is costly. Although other project prioritization studies may recommend periodic reassessment and reallocation, our findings revealed conditions when reallocation is valuable and demonstrated a structured approach that can help conservation agencies schedule and implement iterative budget-allocation decisions cost-effectively.
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    Management strategies for vaccinated animals after an outbreak of foot-and-mouth disease and the impact on return to trade
    Bradhurst, R ; Garner, G ; East, I ; Death, C ; Dodd, A ; Kompas, T ; Parida, S (PUBLIC LIBRARY SCIENCE, 2019-10-11)
    An incursion of Foot-and-mouth disease (FMD) in a previously FMD-free country can cause significant economic damage from immediate and prolonged closure of FMD-sensitive markets. Whilst emergency vaccination may help contain disease, the presence of vaccinated animals complicates post-outbreak management and the recovery of FMD-free status for return to trade. We present enhancements to the Australian Animal DISease (AADIS) model that allow comparisons of post-outbreak management strategies for vaccinated animals, for the purposes of securing the earliest possible return to trade. Two case studies are provided that compare the retention of vaccinated animals with removal for waste/salvage, and the impact on recovery of FMD-sensitive markets per OIE guidelines. It was found that a vaccinate-and-retain strategy was associated with lower post-outbreak management costs, however this advantage was outweighed by significantly higher trade losses. Under the assumptions of the study there was no cost advantage to salvaging the removed vaccinated animals.
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    Prioritizing plant eradication targets by re-framing the project prioritization protocol (PPP) for use in biosecurity applications
    Dodd, AJ ; Ainsworth, N ; Hauser, CE ; Burgman, MA ; McCarthy, MA (Springer, 2017-03-01)
    The eradication of newly detected alien plant species is often prescribed, but rarely successful. Eradication programs fail for many reasons, however, for eradication to remain a cost-efficient management option it is clear that good decisions must be made at the outset. Here we re-frame the project prioritization protocol (PPP), a tool widely used in conservation biology, for use with the metrics typically used by a biosecurity agency. We then use existing methods to estimate the cost-efficiency of eradicating 50 hypothetical species incursions and compare the reduction in weed risk achieved by allocating resources using the PPP framework with the allocation based on risk ranking. By allocating resources to plant eradication programs using the PPP our analysis indicated that it is possible to improve the return on public expenditure by 25% compared to investing based solely on weed risk assessment scores. We also demonstrate how the cost-efficiency of the overall portfolio is influenced by the choice of planning horizon; including the decline in overall portfolio performance that arises when attempting to eradicate individual species too quickly. Finally, we discuss the logistical benefits to a management agency that arise from the use of a generic overarching framework such as the PPP. We believe that the PPP has considerable potential for use in biosecurity and can help focus attention on those species where management can make the biggest difference.
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    Identifying hotspots of alien plant naturalisation in Australia: approaches and predictions
    Dodd, AJ ; McCarthy, MA ; Ainsworth, N ; Burgman, MA (SpringerLink, 2016)
    Her Majesty the Queen in Right of Australia as represented by: Sally Salmon The early detection of newly naturalised alien species is vital to ensuring the greatest chance of their successful eradication. Understanding where species naturalise most frequently is the first stage in allocating surveillance effort. Using Australia’s Virtual Herbarium, we compiled the collection records for all plant species in Australia. We controlled for potential spatial biases in collection effort to identify areas that have an elevated rate of first records of alien species’ occurrence in Australia. Collection effort was highly variable across Australia, but the most intense collection effort occurred either close to herbaria (located in cities) or in remote natural environments. Significant clusters of first records of occurrence were identified around each state’s capital city, coinciding with higher collection effort. Using Poisson point process modelling, we were able to determine the relative influence of environmental and anthropogenic factors on the spatial variation in the risk of species naturalisation. Effort-corrected naturalisation risk appeared to be strongly related to land use, road and human population densities, as well as environmental factors such as average temperature and rainfall. Our paper illustrates how the risk of naturalisation at a location can be estimated quantitatively. Improved understanding of factors that contribute to naturalisation risk enhances allocation of surveillance effort, thereby detecting novel species sooner, and increasing the likelihood of their eventual eradication.
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    The changing patterns of plant naturalization in Australia
    Dodd, AJ ; Burgman, MA ; McCarthy, MA ; Ainsworth, N ; Duncan, R (WILEY, 2015-09)
    Abstract Aim To identify the temporal patterns of plant naturalization in Australia, particularly the interaction between taxonomy, geographic origin and economic use. Location Australia. Methods From Australia's Virtual Herbarium, we compiled a database of information for the entire naturalized flora of Australia. We then examined the database in discrete time intervals to determine the changes in patterns of naturalized species taxonomy, geographic origin and economic use over time. Results Contrary to prevailing hypotheses, we found no evidence to indicate that the rate of alien flora naturalization is increasing in Australia. The number of naturalized species has grown linearly during the period 1880–2000, with the underlying rate of new species detected per thousand specimens declining over the same time period. Despite this, the diversity of both species taxonomy and geographic origin has increased over the last 120 years, leading to increased rates of growth in the total phylogenetic diversity of the Australian flora. Main Conclusions By classifying species according to their likely origin and economic use, we are able to infer the circumstances driving the patterns of naturalization. In particular, we identify how the contribution of individual pathways has changed since European settlement corresponding with the socio‐economic development of the continent. Our study illustrates how the changing nature of ‘high‐risk’ pathways is relevant to directing interventions such as biosecurity regulation.
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    Plant extirpation at the site scale: implications for eradication programmes
    Dodd, AJ ; Ainsworth, N ; Burgman, MA ; McCarthy, MA ; Wilson, JRU (WILEY, 2015-02)
    Abstract Aim To identify the relative importance of commonly available site and species factors on the probability of extirpating a plant species at the site scale. Location Australia. Methods We reviewed the plant eradication literature and listed the factors commonly cited as influencing eradication success. We then analysed a database of 408 site‐scale extirpation attempts, across 17 species eradication programmes, by modelling the time until extirpation to determine the relative influence of these factors on the probability of extirpation, given time. Results The most commonly cited factors influencing eradication success can be classified into two groups as follows: those related to the ‘organisation’, being typically binary variables and amenable to management; and those related to the ‘site/species’, which typically were continuous values and usually beyond the control of the management agency. Detectability period, search distance, monitoring rate, infestation size, propagule longevity, time to reproductive maturity and previous eradication success all influenced the extirpation rate. Conversely, climate suitability, land use and general accessibility (distance to nearest manager) were relatively unimportant. By relating the influential site/species factors to a time‐dependent model, managers and policymakers can explicitly estimate the probability of successful extirpation at a site, given a particular time horizon. These estimates can then be aggregated up to the species scale to allow managers to set realistic goals regarding eradication time frames and resource requirements. Main conclusions Our paper illustrates how the probability of extirpation at the site scale can be quantitatively estimated and how these estimates can be used to inform decisions regarding broader species‐scale eradication programmes. We expect that the use of such quantitative approaches to select better eradication targets will improve eradication success rates over time.