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Preparing for exotic and notifiable aquatic animal disease threats - FC1185

Exotic aquatic animal diseases present a serious threat to wild and farmed aquatic animal diseases. Import risk analysis provides a defensible and transparent tool for assessing these threats and identifying measures to minimise the risk. Effective surveillance is crucial to ensure disease incursions are quickly detected. Rapid and effective disease response relies on contingency planning. This project draws on a range of modelling approaches to produce a robust scientific underpinning to national biosecurity, surveillance and contingency planning for exotic aquatic animal disease threats.

Evidence-based risk analysis is central to the Sanitary and Phytosanitary (SPS) agreement of the World Trade Organization (WTO). Measures, such as the restriction of interntional trade, to protect animal, plant or human health should be based on scientific principles (WTO, 1995). In this project a standard risk assessment framework for assessing exotic disease threats that takes into account environmental and economic consequences will be developed. The method will draw on best practice, reflect international codes and develop the methods to assess the likely consequences of disease incursions. Exotic diseases threats will be assessed systematically using this approach. Live fish generally present the most important route of exotic disease introduction. The large majority of live fish imports are ornamenal fish. The risks associated with ornamental fish will be assessed. If it can be demonstrated that an exporting country is free from a disease, the likelihood of importation of the disease is zero. Surveillance methods have been developed using scenario tree modelling that integrate a range of sources of information from structured surveys to passive surveillance to demonstrate disease freedom (Martin et al, 2007). These approaches will be applied to aquatic animal diseases and thus provide a robust method to generate the evidence base to demonstrate freedom. The same approach can also be used during a disease outbreak to demonstrate freedom at a farm or river level. Surveillance methods will be further supported through risk mapping. Many aquatic animal diseases are temperature sensitive and will only establish or cause clinical signs between a permissive temperature range. A GIS will be developed that integrates metrological, animal population and pathogen survival and lifecycle data to map the likely distribution and impact of selected exotic pathogens (epizootic ulcerative necrosis and epizootic ulcerative syndrome).

Considerable work has already been done on modelling the spread of exotic diseases under FC 1153 (Sharkey et al., 2006). The stochastic model generated by this project needs to be validated and developed for used in contingency planning for the major exotic disease threats (e.g. viral haemorrhagic septicaemia and infectious haematopoeitic necrosis). Further methodological development is needed to model the within farm epidemic and pathogen decay in freshwater. The model will be used to assess the efficacy of competing disease control strategies and to develop outbreak scenarios for planning resources requirements and testing contingency plans. The suitability of the model for use tactically during an outbreak will be determined. Social network analysis will be used to investigate the spread of disease between coarse (e.g. carp) fish farms and fisheries. The work will provide insights into the likely spread of koi herpes virus in England and Wales; they will also inform the development of risk based surveillance.

EC fish health directive 2006/88 requires member states to have in place effective contingency plans and to employ risk based surveillance for notifiable diseases. This project supports the development of fish health policy in both areas.

Martin, P.A.J., Cameron, A.R., Greiner, M., 2007. Demonstrating freedom from disease using multiple complex data sources. 1: A new methodology based on scenario trees. Preventive Veterinary Medicine 79, 71-97.

Sharkey, K.J., Fernandez, C., Morgan, K.L., Peeler, E., Thrush, M., Turnbull, J.F., Bowers, R.G., 2006. Pair-level approximations to the spatio-temporal dynamics of epidemics on asymmetric contact networks. Journal of Mathematical Biology 53, 61-85.

WTO, 1995. Agreement on the Application of Sanitary and Phytosanitary Measures. World Trade Organisation, Geneva, p. 21.
1. Standard import risk assessment framework for exotic aquatic animal disease threats.

A comprehensive handbook on IRA for aquatic animal pathogens will be produced that reflects important differences between classes of aquatic animals. The work will include a review of best practice, outbreak scenarios and generic scenarios for pathogen introduction and establishment.

2. Completed Risk assessments for the main exotic aquatic animal pathogens.

Using the protocols develop in objective 1, IRA for key exotic pathogens and ornamental fish will be completed.

3. Development of surveillance strategies to demonstrate freedom for the main exotic aquatic animal pathogens.

Surveillance strategies that use a wide range of diverse sources to demonstrate freedom will be developed for the most important exotic pathogens. The results will inform the development of contingency planning.

4. A risk map for the distribution and impact of exotic disease threats (epizootic haematopoietic necrosis, EHN and epizootic ulcerative syndrome, EUS)

Risk maps for pathogens with permissive temperature ranges will be developed. The results will inform the development of risk based surveillance.

5. Models to support contingency planning and decision for notifiable diseases.

An existing stochastic model will be parameterised for IHNV and VHSV. A social network model will be developed to investigate spread of coarse fish infections.

Time-Scale and Cost
From: 2009

To: 2013

Cost: £471,445
Contractor / Funded Organisations
Animal Diseases              
Disease Prevention              
Fish Disease              
Fields of Study
Fish Health and Aquaculture