The black summer bushfires: impacts and risk factors for livestock bushfire injury in south-eastern Australia.

BACKGROUND: The 2019/2020 Australian bushfires were the largest bushfire event in modern Australian history. While actions to mitigate risk to homes from bushfires are well reported, there is very little research reported on the impacts of bushfires on livestock. With an increasing incidence of bushfires predicted, there is an urgent need to identify how farmers can best protect their livestock. OBJECTIVES: Compare bushfire affected farms with and without injured livestock to identify associations between risk factors and bushfire injury. Infer management approaches that can be used to reduce bushfire injury in livestock. METHOD: A case-control study using a structured interview questionnaire, delivered in late 2020 to cattle and sheep farmers in south-eastern Australia (New South Wales and Victoria) whose farmland was burnt in the 2019/2020 Australian bushfires. Case farms were farms with bushfires injured or killed livestock. Control farms were farms that had no bushfire injured livestock but that still had fire present on the farm. Interview responses were summarised and information theoretical approaches were used to identify potential risk factors for livestock bushfire injury and protective actions that could inform future fire-preparation recommendations. RESULTS AND DISCUSSION: Of 46 farms in the case-control study, 21 (46%) reported bushfire injured or killed livestock. Apparent protective factors identified included: preparation (having a bushfire plan and more than two farm bushfire fighting units), backburning and receiving assistance from fire authorities. Combined beef and sheep grazing enterprises appeared to have an increased risk of bushfire injury to livestock.

Modelling foot-and-mouth disease transmission in a wild pig-domestic cattle ecosystem.

OBJECTIVE: To use simulation modelling to predict the potential spread and to explore control options for a foot-and-mouth disease (FMD) incursion in a mixed wild pig-domestic cattle ecosystem in northern Australia. DESIGN: Based on aerial surveys, expert opinion and published data, the wild pig and grazing cattle distributions were simulated. A susceptible-infected-resistant disease-spread model was coded and parameterised according to published literature and expert opinion. METHODS: A baseline scenario was simulated in which infection was introduced via wild pigs, with transmission from pigs to cattle and no disease control. Assumptions regarding disease transmission were investigated via sensitivity analyses. Predicted size and length of outbreaks were compared for different control strategies based on movement standstill, surveillance and depopulation. RESULTS: In most of the simulations, FMD outbreaks were predicted to be ongoing after 6 months, with more cattle herds infected than wild pig herds (median 907 vs. 22, respectively). Assuming only pig-to-pig transmission, the infection routinely died out. In contrast, assuming cattle-to-cattle, cattle-to-pig or pig-to-cattle transmission resulted in FMD establishing and spreading in more than 75% of simulations. A control strategy targeting wild pigs only was not predicted to be successful. Control based on cattle only was successful in eradicating the disease. However, control targeting both pigs and cattle resulted in smaller outbreaks. CONCLUSIONS: If FMD is controlled in cattle in the modelled ecosystem, it is likely to be self-limiting in wild pigs. However, to eradicate disease as quickly as possible, both wild pigs and cattle should be targeted for control.

Diagnostic specificity of an equine influenza blocking ELISA estimated from New South Wales field data from the Australian epidemic in 2007.

This observational study was undertaken in order to evaluate the diagnostic specificity of the blocking enzyme-linked immunosorbent assay (bELISA) for serum antibodies to influenza A virus nucleoprotein during the equine influenza (EI) outbreak response in New South Wales, Australia, in 2007. Using data collected during the outbreak response, bELISA testing data were collated for assumed uninfected horses from areas where EI infection was never recorded. Diagnostic specificity of the bELISA used during the EI response was high, but varied significantly between some regions, although the reason(s) for this variation could not be determined.

Regaining Australia's equine influenza-free status: a national perspective.

The first cases of equine influenza (EI) in Australia were reported in late August 2007. By 14 March 2008, provisional freedom from EI was declared and in December 2008 Australia was officially declared EI-free, 12 months after the last reported clinical case. Containment, and ultimate eradication, of EI was achieved through a combination of movement restrictions, zoning, vaccination and enhanced biosecurity measures that drew on the resources and expertise of industry and state and federal governments. Through these measures, the EI outbreak, which peaked in October 2007, was contained to just 3% of Australia, with no new cases reported after 9 December 2007, just four months after the outbreak began.

Vaccination of feral pigs (Sus scrofa) using iophenoxic acid as a simulated vaccine.

OBJECTIVES: To develop an encapsulation method for delivery of vaccines to feral pigs, and quantify the effect of iophenoxic acid on captive feral pig blood iodine concentrations to assist in investigation of factors affecting vaccine uptake. DESIGN AND METHODS: Feral pigs were administered iophenoxic acid by oral gavage, and consumption was assessed for different encapsulation methods in baits. Blood iodine concentrations were monitored for eight days after consumption. The relationship between dose rate, time since dosing and blood iodine concentration was assessed for gavaged and baited captive feral pigs. Wild feral pigs were baited with PIGOUT baits containing 20 mg of encapsulated iophenoxic acid to simulate a vaccination program. Using knowledge from the pen studies, bait uptake and factors affecting bait uptake were investigated. RESULTS: Bait-delivered iophenoxic acid led to variable and inconsistent changes in blood iodine concentrations, in contrast to pigs receiving iophenoxic acid by gavage. This precluded accurate assessment of the quantity consumed, but still allowed a conservative determination of bait uptake. Iophenoxic acid in smaller capsules was consumed readily. Increasing baiting intensity appeared to increase bait uptake by wild feral pigs, and pigs of varying sexes, ages and weights appeared equally likely to consume baits. CONCLUSIONS: Encapsulated liquids can be delivered to feral pigs within baits, should the need to vaccinate feral pigs for fertility or disease management arise. High baiting intensities may be required.