The economic benefits of targeted response strategies against foot-and-mouth disease in Australia.

Recent developments in control of highly infectious diseases attempt to improve emergency response efforts by more clearly focusing or targeting response tools according to risk. For example, advances in surveillance testing and sampling deliver their results by more accurately and precisely targeting the population of interest. In this work, targeted implementation of trading zones and vaccination were examined for simulated outbreaks of foot-and-mouth disease (FMD) in Australia. Trading zones allowing unaffected Australian states to resume exports following an outbreak of FMD were assessed using multiple tools. A Victorian incursion scenario with traditional stamping out and vaccination as control options, was simulated using the AADIS model Version 2.47, to characterise the geographic extent of potential outbreaks, the number of animals infected, and the date of last cull indicating duration of the outbreak. Information on disease spread from the AADIS simulations was then used to identify the boundaries of trading zones for the incursion scenario, in which vaccination with trading zones was found to further reduce disease impacts relative to stamping out alone with trading zones. The number of animals culled due to disease provided supply shocks for stamping out alone and vaccinate-to-retain, while the number of vaccinated animals was added to the number of animals culled due to disease for the supply shock of vaccinate-to-remove. The day of last cull was combined with historical FMD trade recovery and Australian export data to estimate the share of Australian exports that would be embargoed under trading zones. The market impacts - changes in equilibrium quantities and prices - of the supply shock, trading zones, and consumer reactions - were simulated within ABARES' AgEmissions partial equilibrium model of Australian agriculture. For this simulated large outbreak, where vaccinate-to-remove was utilised along with trading zones, producer losses were reduced by AUD 4 billion in present value terms over 10 years estimated at a 7% discount rate (PV10,7%) compared to an outbreak where stamping out alone is applied with trading zones. Introducing FMD virus risk mitigation measures for wool to further target trading zones reduced the economic impacts by an additional AUD 3.6 billion (PV10,7%). Outbreak response cost savings and additional potential costs under vaccinate-to-retain with trading zones were also compared to the vaccinate-to-remove control with trading zones. Results emphasised the importance of outbreak characteristics in determining trading zones and targeting of vaccination. Economic analyses identified how additional investments in targeting outbreak response is of value to producers.

A Simulation Study of the Use of Vaccination to Control Foot-and-Mouth Disease Outbreaks Across Australia.

This study examines the potential for foot-and-mouth disease (FMD) control strategies that incorporate vaccination to manage FMD spread for a range of incursion scenarios across Australia. Stakeholder consultation was used to formulate control strategies and incursion scenarios to ensure relevance to the diverse range of Australian livestock production regions and management systems. The Australian Animal Disease Spread model (AADIS) was used to compare nine control strategies for 13 incursion scenarios, including seven control strategies incorporating vaccination. The control strategies with vaccination differed in terms of their approaches for targeting areas and species. These strategies are compared with two benchmark strategies based on stamping out only. Outbreak size and duration were compared in terms of the total number of infected premises, the duration of the control stage of an FMD outbreak, and the number of vaccinated animals. The three key findings from this analysis are as follows: (1) smaller outbreaks can be effectively managed by stamping out without vaccination, (2) the size and duration of larger outbreaks can be significantly reduced when vaccination is used, and (3) different vaccination strategies produced similar reductions in the size and duration of an outbreak, but the number of animals vaccinated varied. Under current international standards for regaining FMD-free status, vaccinated animals need to be removed from the population at the end of the outbreak to minimize trade impacts. We have shown that selective, targeted vaccination strategies could achieve effective FMD control while significantly reducing the number of animals vaccinated.

A comparison of fragmenting lead-based and lead-free bullets for aerial shooting of wild pigs.

In response to the health threats posed by toxic lead to humans, scavenging wildlife and the environment, there is currently a focus on transitioning from lead-based to lead-free bullets for shooting of wild animals. We compared efficiency metrics and terminal ballistic performance for lead-based and lead-free (non-lead) bullets for aerial shooting of wild pigs (Sus scrofa) in eastern Australia. Ballistic testing revealed that lead-based and lead-free bullets achieved similar performance in precision and muzzle kinetic energy (E0) levels (3337.2 J and 3345.7 J, respectively). An aerial shooting trial was conducted with wild pigs shot with one type of lead-based and one type of lead-free bullets under identical conditions. Observations were made from 859 shooting events (n = 430 and 429 respectively), with a sub-set of pigs examined via gross post-mortem (n = 100 and 108 respectively), and a further sub-set examined via radiography (n = 94 and 101 respectively). The mean number of bullets fired per pig killed did not differ greatly between lead-based and lead-free bullets respectively (4.09 vs 3.91), nor did the mean number of bullet wound tracts in each animal via post-mortem inspection (3.29 vs 2.98). However, radiography revealed a higher average number of fragments per animal (median >300 vs median = 55) and a broader distribution of fragments with lead-based bullets. Our results suggest that lead-based and lead-free bullets are similarly effective for aerial shooting of wild pigs, but that the bullet types behave differently, with lead-based bullets displaying a higher degree of fragmentation. These results suggest that aerial shooting may be a particularly important contributor to scavenging wildlife being exposed to lead and that investigation of lead-free bullets for this use should continue.

Risk factors for emergence of exotic foot-and-mouth disease O/ME-SA/Ind-2001d on smallholder farms in the Greater Mekong Subregion.

Foot-and-mouth disease (FMD) is a significant endemic transboundary animal disease in Lao People's Democratic Republic (Lao PDR) and throughout the Greater Mekong Subregion (GMS). The disease has been shown to perpetuate the cycle of smallholder poverty through reduced animal production, plus limitations on market access for trading in livestock and their products. Despite significant national and multilateral efforts to control FMD over the past two decades, endemic FMD viruses (FMDVs) continue to circulate in Lao PDR. Further, the threat from new and emerging FMDVs is increasing as transboundary movements in the region intensify in response to increasing regional demand for meat. Although the economic impacts of FMD on smallholder farmers in Lao PDR are significant, studies investigating household-level risk factors for FMD are lacking. Following an outbreak of a novel FMDV (O/ME-SA/Ind2001d) in Lao PDR in 2015, a questionnaire and serological study were conducted in Naxaythong District to identify household-level risk factors associated with this outbreak, as well as endemic circulating viruses in the outbreak area. Data were analysed using a multivariable generalised estimating equation (GEE) model with a logit link function and associations were calculated as odds ratios (OR) with 95% confidence intervals (CI95%). After adjusting for other variables, the practice of quarantining new livestock for a minimum of two weeks prior to introduction to a herd was found to be a significant protective factor during the 2015 outbreak (OR 0.225, CI95% [0.06, 0.88], p-value 0.003). In addition, households owning one or more animals with titres to the non-structural proteins of FMDV, indicating prior infection, had 5.5 times the odds (CI95% [6.16, 49.11], p-value <0.001) of sharing communal grazing land with neighbouring villages. These findings indicate that implementing basic on-farm biosecurity and improved husbandry measures to minimise FMDV circulation at the household level are important and reinforce the need to enhance the education of smallholder farmers in infectious disease control.