"Why won't they just vaccinate?" Horse owner risk perception and uptake of the Hendra virus vaccine.

BACKGROUND: Hendra virus is a paramyxovirus that causes periodic serious disease and fatalities in horses and humans in Australia first identified in 1994. Pteropid bats (commonly known as flying-foxes) are the natural host of the virus, and the putative route of infection in horses is by ingestion or inhalation of material contaminated by flying-fox urine or other bodily fluids. Humans become infected after close contact with infected horses. Horse owners in Australia are encouraged to vaccinate their horses against Hendra virus to reduce the risk of Hendra virus infection, and to prevent potential transmission to humans. After the vaccine was released in 2012, uptake by horse owners was slow, with some estimated 11-17% of horses in Australia vaccinated. This study was commissioned to examine barriers to vaccine uptake and potential drivers to future adoption of vaccination by horse owners. METHODS: This study examined qualitative comments from respondents to an on-line survey, reporting reasons for not vaccinating their horses. The study also investigated scenarios in which respondents felt they might consider vaccinating their horses. RESULTS: Self-reported barriers to uptake of the Hendra virus vaccine by horse owners (N = 150) included concerns about vaccine safety, cost, and effectiveness. Reduction in vaccination costs and perception of immediacy of Hendra virus risk were reported as being likely to change future behaviour. However, the data also indicated that horse owners generally would not reconsider vaccinating their horses if advised by their veterinarian. CONCLUSION: While changes to vaccine costs and the availability data supporting vaccine safety and efficacy may encourage more horse owners to vaccinate, this study highlights the importance of protecting the relationship between veterinarians and horse owners within the risk management strategies around Hendra virus. Interactions and trust between veterinarians and animal owners has important implications for management of and communication around Hendra virus and other zoonotic disease outbreaks.

Risk Mitigation of Emerging Zoonoses: Hendra Virus and Non-Vaccinating Horse Owners.

Hendra virus was identified in horses and humans in 1994, in Queensland, Australia. Flying foxes are the natural host. Horses are thought to acquire infection by direct or indirect contact with infected flying fox urine. Humans are infected from close contact with infected horses. To reduce risk of infection in horses and humans, Australian horse owners are encouraged to vaccinate horses against the virus and adopt property risk mitigation practices that focus on reducing flying fox horse contact and contamination of horses' environment with flying fox bodily fluids. This study investigates uptake of four Hendra virus risk mitigation practices in a sample of non- and partially vaccinating horse owners living close to previous Hendra virus cases. Protection motivation theory was used to develop a conceptual model to investigate risk perception and coping factors associated with uptake of risk mitigation practices. An online survey was administered via Facebook pages of veterinary clinics close to previous Hendra virus cases. Factors associated with uptake of risk mitigation practices were investigated using univariate and multivariate binary logistic regression. Belief that a risk mitigation practice would be effective in reducing Hendra virus risk was significantly associated with the uptake of that practice. Issues around the practicality of implementing risk mitigation practices were found to be the greatest barrier to uptake. Factors that relate to risk immediacy, such as nearby infection, were identified as more likely to trigger uptake of risk mitigation practices. The role of veterinarians in supporting Hendra risk mitigation was identified as more influential than that of respected others or friends. Findings from this study are being used to assist stakeholders in Australia responsible for promotion of risk mitigation practice in identifying additional pathways and reliable influencing factors that could be utilized for engaging and communicating with horse owners to promote Hendra virus risk mitigation behaviour.

Leaf emergence of spring wheat receiving varying nitrogen supply at different stages of development.

We examined effects of nitrogen (N) supply on leaf emergence of spring wheat (Triticum aestivum L.) grown in sand with nutrient solution containing different N concentrations (9NO3: 1NH4). In expt 1, the cultivar 'Gamenya' received nutrient solution twice weekly containing a constant N supply ranging from 50 to 2400 microM N. In expts 2 and 3, cultivars 'Aroona' and 'Gamenya' were irrigated hourly with nutrient solution containing either low (L = 50 micrroM N) or high (H = 2000 microM N) N supply. In expt 2, the N supply to half of the plants receiving L and H was changed at the double ridge stage of apical development, producing plants receiving LL, LH, HL and HH. In expt 3, N supply was changed firstly when the main stem apex was vegetative (one to two leaves) and secondly when the main stem apex was at double ridge stage (four to five leaves), producing plants receiving LLL, LHL, HLH and HHH. Leaves on the main stem and primary tillers were counted. Rate of leaf emergence was estimated from regression of number of leaves against thermal time; the phyllochron was calculated as 1/ rate of emergence. Severely N-deficient plants (which had at least a 60 % reduction in shoot dry weight) had slower rates of leaf emergence (expt 1). Fluctuating N supply sometimes, but not always, changed the rate of leaf emergence (expts 2 and 3). The N supply before double ridge stage had bigger effects on the phyllochron than that afterwards (expt 3). The phyllocrons of the main stems were generally lower than those of tillers, with a greater difference between stems in N-deficient plants. Low N supply at the vegetative apex stage decreased the total number of leaves on the main stem, while low N supply after double ridge did not.

Accumulation of apoplastic iron in plant roots : a factor in the resistance of soybeans to iron-deficiency induced chlorosis?

We hypothesized that the resistance of Hawkeye (HA) soybean (Glycine max L.) to iron-deficiency induced chlorosis (IDC) is correlated to an ability to accumulate a large pool of extracellular-root iron which can be mobilized to shoots as the plants become iron deficient. Iron in the root apoplast was assayed after efflux from the roots of intact plants in nutrient solution treated with sodium dithionite added under anaerobic conditions. Young seedlings of HA soybean accumulated a significantly larger amount of extracellular iron in their roots than did either IDC-susceptible PI-54619 (PI) soybean or IDC-resistant IS-8001 (IS) sunflower (Helianthus annus L.). Concurrently, HA soybean had much higher concentrations of iron in their shoots than either PI soybean or IS sunflower. The concentration of iron in the root apoplast and in shoots of HA soybean decreased sharply within days after the first measurements of extracellular root iron were made, in both +Fe and -Fe treatments. The accumulation of short-term iron reserves in the root apoplast and translocation of iron in large quantities to the shoot may be important characteristics of IDC resistance in soybeans.