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Palmerston North, New Zealand

Stevenson M.A.,Massey University | Sanson R.L.,AsureQuality Ltd | Stern M.W.,Massey University | O'Leary B.D.,Massey University | And 3 more authors.
Preventive Veterinary Medicine | Year: 2013

We describe the spatially explicit, stochastic simulation model of disease spread, InterSpread Plus, in terms of its epidemiological framework, operation, and mode of use. The input data required by the model, the method for simulating contact and infection spread, and methods for simulating disease control measures are described. Data and parameters that are essential for disease simulation modelling using InterSpread Plus are distinguished from those that are non-essential, and it is suggested that a rational approach to simulating disease epidemics using this tool is to start with core data and parameters, adding additional layers of complexity if and when the specific requirements of the simulation exercise require it.We recommend that simulation models of disease are best developed as part of epidemic contingency planning so decision makers are familiar with model outputs and assumptions and are well-positioned to evaluate their strengths and weaknesses to make informed decisions in times of crisis. © 2012 Elsevier B.V..

Gloster J.,UK Met Office | Burgin L.,UK Met Office | Jones A.,UK Met Office | Sanson R.,AsureQuality Ltd
OIE Revue Scientifique et Technique | Year: 2011

Atmospheric dispersion models can be used to assess the likely airborne spread of both plant and animal diseases. These models, often initially developed for other purposes, can be adapted and used to study past outbreaks of disease as well as operationally to provide advice to those responsible for containing or eradicating disease in the event of a specific emergency. The models can be run over short periods of time where emissions and infection periods can be accurately determined or in situations requiring a statistical approach perhaps covering many weeks or even months. They can also be embedded within other simulation models, i.e. models which seek to represent a wider variety of disease transmission mechanisms. Whilst atmospheric dispersion models have been used successfully in a number of instances, they have the potential for wider application in the future. To achieve maximum success in these ventures, close collaboration between the modellers and scientists from the appropriate range of disciplines is required.

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.

Sanson R.L.,AsureQuality Ltd | Dube C.,Canadian Food Inspection Agency | Cork S.C.,University of Calgary | Frederickson R.,Alberta Agriculture and Rural Development | Morley C.,Alberta Agriculture and Rural Development
Preventive Veterinary Medicine | Year: 2014

This study describes the use of simulation modelling to evaluate the predicted benefits of an effective livestock traceability system in responding to a hypothetical introduction of foot-and-mouth disease (FMD) in to the province of Alberta, Canada, and whether or not the implementation of emergency ring vaccination in addition to a standard stamping-out (SO) strategy would lead to smaller and shorter epidemics. Three introduction scenarios were defined, with the primary case in either an intensive beef feedlot operation, an extensive cow-calf operation or in a swine operation. Disease spread was simulated using, three levels of tracing effectiveness, five types of vaccination zone, three different vaccination start times, three lengths of vaccination campaigns, two levels of culling resource and using FMD strains with two different virulence levels. Using standard SO procedures (without vaccination), improving traceability effectiveness from a level whereby only 65% of movements were traced within 5-7 days, to a capability whereby all movements were traced within 1 day, led to a reduction in the number of infected premises (IPs) between 18.7 and 64.5%, an average saving of CAN$29,000,000 in livestock compensation costs alone, and a reduction in the length of epidemics ranging from 1 to 22 days. The implementation of emergency vaccination also led to a reduction in the number of IPs and a shortening of epidemics. The effects were more pronounced when the higher virulence settings were used, with a predicted reduction in IPs of 16.6-68.7% (mean. = 48.6%) and epidemics shortened by up to 37 days. Multi-variable analyses showed these effects were highly significant, after accounting for the incursion location, virulence of virus and time of first detection. The results clearly demonstrated the benefits of having effective traceability systems with rapid query and reporting functionality. The results also supported the value of early vaccination as an adjunct to SO in reducing the number of IPs and shortening the length of the epidemics. The most effective vaccination strategy involved a 3. km or larger suppressive vaccination zone around all IPs, begun as soon as practicable after first detection, and which continued until the last IP was detected. © 2014 Elsevier B.V.

Stringer L.D.,The New Zealand Institute for Plant and Food Research Ltd | Suckling D.M.,The New Zealand Institute for Plant and Food Research Ltd | Mattson L.T.W.,AsureQuality Ltd | Peacock L.R.,MAF Biosecurity New Zealand
New Zealand Plant Protection | Year: 2010

The National Invasive Ant Surveillance is conducted annually around ports and other high-risk areas to detect new ant incursions into New Zealand. Currently, non-sticky food-baited vials are used to trap ants. The ability of a sticky bait trap to trap multiple ant species at baits was tested, under the hypothesis that a sticky trap would reduce the role of competitive exclusion at food sources, a drawback of food baiting. Furthermore, the role of food type, sugar, protein and a combination of both foods, on ant catch was examined. Although only 4% of traps caught multiple species, this incidence was five times greater in the sticky-bait than food-only vials. The combined food source traps caught ants more often than the single food source traps. The refinement of ant monitoring traps will aid surveillance managers in the future.

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