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Australian Capital Territory, Australia

East I.J.,Office of the Chief Veterinary Officer | Ainsworth C.,Australian Department of Primary Industries and Fisheries | Warner S.,Australian Department of Primary Industries and Fisheries | Dunowska M.,Australian Department of Primary Industries and Fisheries | Azuolas J.K.,Australian Department of Primary Industries and Fisheries
Australian Veterinary Journal | Year: 2010

Background: Since 2005, H5N1 avian influenza (AI) has spread from South-East Asia to over 60 different countries, resulting in the direct death or slaughter of over 250,000,000 poultry. Migratory waterfowl have been implicated in this spread and in Australia there have been numerous isolations of low-pathogenicity AI virus from wild waterfowl and shorebirds. The Department of Human Services, Victoria maintains 10 sentinel free-range chicken flocks in the Riverland at locations that are populated by large numbers of waterfowl known to carry a range of strains of AI. Objective: This study analysed historical samples collected in 1991-94 and 2003-06 from the library of serum samples for antibodies against AI to assess the potential for transfer of AI virus from wild waterfowl to free-range poultry. Results: Of the 2000 serum samples analysed, 17 were positive for antibodies against AI and 87 were suspect, with a clustering of positive and suspect results in the years 1994, 2003 and 2004. There was also a clustering of positive samples at the site of the Barmah flock. Nine sequential sets of sera from individual chickens with at least one positive result were identified. Analysis of these sequential sets showed that infection was acquired on site but that the antibody response to AI infection was short-lived and was no longer detectable at 8 weeks after the positive finding. Conclusion: The surveillance of sentinel chickens is a potential avenue for monitoring the circulation of AI viruses and could provide an early warning system for the commercial poultry industries. © 2010 The Authors. Journal compilation © 2010 Australian Veterinary Association. Source


Sansoni R.L.,AsureQuality Ltd | Harvey N.,University of Guelph | Garner M.G.,Office of the Chief Veterinary Officer | Stevenson M.A.,Massey University | And 6 more authors.
OIE Revue Scientifique et Technique | Year: 2011

Researchers from Australia, New Zealand, Canada and the United States collaborated to validate their foot and mouth disease models - AusSpread, InterSpread Plus and the North American Animal Disease Spread Model - in an effort to build confidence in their use as decision-support tools. The final stage of this project involved using the three models to simulate a number of disease outbreak scenarios, with data from the Republic of Ireland. The scenarios included an uncontrolled epidemic, and epidemics managed by combinations of stamping out and vaccination. The predicted numbers of infected premises, the duration of each epidemic, and the size of predicted outbreak areas were compared. Relative within-model between-scenario changes resulting from different control strategies or resource constraints in different scenarios were quantified and compared. Although there were differences between the models in absolute outcomes, between-scenario comparisons within each model were similar. In all three models, early use of ring vaccination resulted in the largest drop in number of infected premises compared with the standard stamping-out regimen. This consistency implies that the assumptions made by each of the three modelling teams were appropriate, which in turn serves to increase enduser confidence in predictions made by these models. Source


Barre N.,Institute Agronomique neo Caledonien Center | Happold J.,Office of the Chief Veterinary Officer | Delathiere J.-M.,Service dInspection Veterinaire | Desoutter D.,Service des Laboratoires Officiels Veterinaires | And 6 more authors.
Ticks and Tick-borne Diseases | Year: 2011

In December 2007, Babesia bovis was introduced to New Caledonia through the importation of cattle that had been vaccinated with a live tick fever (babesiosis and anaplasmosis) vaccine. Although the tick Rhipicephalus (Boophilus) microplus is common in New Caledonia, the territory had previously been free of tick-borne diseases of cattle. This paper describes the initial extent of the outbreak, the measures and rationale for disease control, and the progress to date of the eradication campaign. Initially, 22 properties were affected involving approximately 2300 cattle in 'high risk' zones and 1600 in adjoining 'suspect' zones. Rather than slaughtering infected herds or attempting to eliminate the tick vector, the campaign was based on quarantine of affected properties, and aggressive tick control in conjunction with 3-monthly treatments of the high risk cattle with the antiprotozoal drug imidocarb dipropionate. Subsequent surveillance by ELISA and PCR showed a progressive and dramatic decline in seroprevalence among infected herds and the absence of new infections. All 22 properties were considered to be free of Babesia within 12 months of the start of the disease control program. These results indicate that the strategy was effective in eliminating Babesia from infected herds and feasible as an eradication strategy on a moderately large scale. Unfortunately, early in the campaign, babesiosis spread to a herd of feral cattle on a property in the 'suspect' zone, and this reservoir of infection subsequently resulted in the infection (or reinfection) of cattle on several neighbouring commercial farms. The eradication campaign in New Caledonia is currently focussed on destocking the feral cattle - extensive surveillance suggests that this is the only remaining nidus of infection. © 2010 Elsevier GmbH. Source


Cowled B.D.,University of Sydney | Ward M.P.,University of Sydney | Laffan S.W.,University of New South Wales | Galea F.,Australian Department of Primary Industries and Fisheries | And 8 more authors.
PLoS ONE | Year: 2012

Infectious wildlife diseases have enormous global impacts, leading to human pandemics, global biodiversity declines and socio-economic hardship. Understanding how infection persists and is transmitted in wildlife is critical for managing diseases, but our understanding is limited. Our study aim was to better understand how infectious disease persists in wildlife populations by integrating genetics, ecology and epidemiology approaches. Specifically, we aimed to determine whether environmental or host factors were stronger drivers of Salmonella persistence or transmission within a remote and isolated wild pig (Sus scrofa) population. We determined the Salmonella infection status of wild pigs. Salmonella isolates were genotyped and a range of data was collected on putative risk factors for Salmonella transmission. We a priori identified several plausible biological hypotheses for Salmonella prevalence (cross sectional study design) versus transmission (molecular case series study design) and fit the data to these models. There were 543 wild pig Salmonella observations, sampled at 93 unique locations. Salmonella prevalence was 41% (95% confidence interval [CI]: 37-45%). The median Salmonella DICE coefficient (or Salmonella genetic similarity) was 52% (interquartile range [IQR]: 42-62%). Using the traditional cross sectional prevalence study design, the only supported model was based on the hypothesis that abundance of available ecological resources determines Salmonella prevalence in wild pigs. In the molecular study design, spatial proximity and herd membership as well as some individual risk factors (sex, condition score and relative density) determined transmission between pigs. Traditional cross sectional surveys and molecular epidemiological approaches are complementary and together can enhance understanding of disease ecology: abundance of ecological resources critical for wildlife influences Salmonella prevalence, whereas Salmonella transmission is driven by local spatial, social, density and individual factors, rather than resources. This enhanced understanding has implications for the control of diseases in wildlife populations. Attempts to manage wildlife disease using simplistic density approaches do not acknowledge the complexity of disease ecology. © 2012 Cowled et al. Source


Garner M.G.,Office of the Chief Veterinary Officer | Cowled B.,Office of the Chief Veterinary Officer | East I.J.,Office of the Chief Veterinary Officer | Moloney B.J.,Australian Department of Primary Industries and Fisheries | Kung N.Y.,Australian Department of Primary Industries and Fisheries
Preventive Veterinary Medicine | Year: 2011

In August 2007, Australia which had previously been free of equine influenza, experienced a large outbreak that lasted approximately 4 months before it was eradicated. The outbreak required a significant national response by government and the horse industries. The main components of the response were movement controls, biosecurity measures, risk-based zoning and, subsequently, vaccination to contain the outbreak. Although not initially used, vaccination became a key element in the eradication program, with approximately 140. 000 horses vaccinated. Vaccination is recognised as a valuable tool for managing EI in endemically infected countries but there is little experience using it in situations where the objective is disease eradication. Vaccination was undoubtedly an important factor in 2007 as it enabled movements of some horses and associated industry activities to recommence. However, its contribution to containment and eradication is less clear. A premises-level equine influenza model, based on an epidemiological analysis of the 2007 outbreak, was developed to evaluate effectiveness of the mitigation strategies used and to investigate whether vaccination, if applied earlier, would have had an effect on the course of the outbreak. The results indicate that early use of strategic vaccination could have significantly reduced the size of the outbreak. The four vaccination strategies evaluated had, by 1 month into the control program, reduced the number of new infections on average by 60% and the size of the infected area by 8-9%. If resources are limited, a 1. km suppressive ring vaccination around infected premises gave the best results, but with greater vaccination capacity, a 3. km ring vaccination was the most effective strategy. The findings suggest that as well as reducing clinical and economic impacts, vaccination when used with biosecurity measures and movement controls could play an important role in the containment and eradication of equine influenza. © 2010. Source

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