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Since 1970, aquaculture has grown at a rate of between 5% and 10% per annum. It has achieved this by expanding into new areas, farming new (often non-native) species and intensifying production. These features of aquaculture, combined with large-scale movements of animals, have driven disease emergence, with negative consequences for both production and biodiversity. Efforts to improve the management of emerging diseases of aquatic animals must include actions to reduce the rate of disease emergence, enhance disease detection and reporting, and improve responses to prevent disease spread. The rate of disease emergence can be reduced by understanding the underpinning mechanisms and developing measures to mitigate them. The three principal mechanisms of disease emergence, namely, host switching, decreased host immunocompetence and increased pathogen virulence, have many drivers. The most important of these drivers are those that expose susceptible hosts to novel pathogens (e.g. the introduction of non-native hosts, translocation of pathogens, and increased interaction between wild and farmed populations), followed by host switching. Exposure to wild populations can be reduced through infrastructure and management measures to reduce escapes or exclude wild animals (e.g. barrier nets, filtration and closed-confinement technology). A high standard of health management ensures immunocompetence and resistance to putative new pathogens and strains, and thus reduces the rate of emergence. Appropriate site selection and husbandry can reduce the likelihood of pathogens developing increased virulence by preventing their continuous cycling in geographically or temporally linked populations. The under-reporting of emerging aquatic animal diseases constrains appropriate investigation and timely response. At the producer level, employing information and communications technology (e.g. smartphone applications and Cloud computing) to collect and manage data, coupled with a farmer-centric approach to surveillance, could improve reporting. In addition, reporting behaviours must be understood and disincentives mitigated. At the international level, improving the reporting of emerging diseases to the World Organisation for Animal Health allows Member Countries to implement appropriate measures to reduce transboundary spread. Reporting would be incentivised if the global response included the provision of support to low-income countries to, in the short term, control a reported emerging disease, and, in the longer term, develop aquatic animal health services. Early detection and reporting of emerging diseases are only of benefit if Competent Authorities' responses prevent disease spread. Effective responses to emerging diseases are challenging because basic information and tools are often lacking. Consequently, responses are likely to be sub-optimal unless contingency plans have been developed and tested, and decision-making arrangements have been well established.

The implementation and monitoring of fish health regulations vary extensively in aquaculture throughout the world. In the main salmon-producing countries, there is strict regulatory oversight of the use of pharmaceutical drugs. Such controls have supported the sustainable growth of the aquaculture industry and, in Norway, aquaculture has been able to reduce its total consumption of antibiotics by more than 99% between 1995 and today, yet there has been a 20-fold rise in production volume. Other countries on other continents may have less control, with no mandatory prescription regulations and variable quality of the pharmaceutical products available. A good regulatory framework, with control and monitoring systems, should be established in all countries where aquaculture is practised and veterinary medicinal products should only be available under veterinary prescription and supervision. Many drug resistance genes have been identified, and molecular methods should be applied to control drug resistance in the microbial and parasitic populations of all major aquaculture-producing regions.

This paper presents a critical review of intensive animal farming in the light of past and present global crises, reflecting the fragility of its foundations, its unsustainability and its inability to ensure world food security. A central argument of this paper is that intensive animal farming promotes industrial efficiency, commodity production and the availability of cheap food at the expense of farmed animals, the environment and society. This paper begins by briefly examining the history of world food security and explores the role assigned to animal farming, animal health and public health in this context. It then reviews changing perceptions of world food security during various periods of global instability and their implications for animal farming and animal health and welfare. At the same time, the paper seeks to identify what has so far been missing in discourses around world food security and animal farming, and discusses how these gaps shape and are shaped by specific scientific thinking on animal health and well-being. With the recent exponential growth of aquaculture, the authors' objectives are to examine animal health practices in farming and to understand how animal health science could effectively, in the long term, help animal farming, and in particular aquaculture, to contribute to global food security.

Global food security and nutrition depend heavily on aquaculture, the continued growth of which is crucial as the world heads towards a human population of at least 9 billion by 2050, while harvests from wild capture will, at best, stabilise at current levels. Thus, a fundamental question is: how can we sustainably increase aquatic food production? It is clear that aquatic animal diseases present a substantial threat and, consequently, aquatic animal health management has a critical role in food security. An ecosystem approach to aquaculture will mitigate impacts on ecosystem services and biodiversity, and provide the necessary resilience to future disease threats, including those exacerbated by climate change. Due to the nature of aquatic production systems, this approach must encompass fisheries and other sectors that share the same resources. Improved aquatic animal health management must be a key component of aquaculture's future. At the national level, public-private partnerships are vital in achieving objectives of common benefit. Improved disease reporting and response is critical in the control of listed and emerging diseases and can only be achieved through government, industry and stakeholder collaboration. Great potential exists to improve biosecurity from the farm to national level, but this will only be achieved through collaboration. Industry cannot develop effective biosecurity without a clear government strategy and support, specifically legislation which provides an effective framework for safe trade. Governments have a key role in creating a regulatory environment that supports effective biosecurity and is attractive to investment; such as one that supports the development and regulatory approval of therapeutics. The improved control of transboundary diseases requires the wider and more consistent implementation of OIE standards, particularly on disease notification. This can only be achieved through improved collaboration between trading partners and by supporting low- and middle-income countries to strengthen their aquatic animal health services. There is incredible potential for aquaculture to continue its rapid growth and increase its contribution to global food security. However, sustainable growth of aquaculture is threatened by both known diseases, which we cannot effectively control, and new diseases, which may become pandemic. Recent pandemics have shown that global production systems are epidemiologically connected and, consequently, aquatic animal diseases present a shared global threat that demands global solidarity. The world now depends on a sustainable future for aquaculture and improved aquatic animal health management is critical to its continued and growing contribution to global food security.

In spite of scientific progress, the world is still facing major biological threats. Not only are there epidemics caused by wildlife pathogens under natural conditions, there are also those caused accidently when researchers handle highly hazardous organisms stored in research laboratories, and those caused when countries use these organisms as biological weapons of war or when criminal groups use them for bioterrorism. Developing countries tend to be more vulnerable to such threats than developed countries owing to the poor resilience of their animal health systems, their advanced state of environmental degradation, their socio-economic fragility and their political instability. The occurrence of emerging and re-emerging diseases (avian influenza, Ebola virus disease) has caused deep concern around the world in recent years and has shown how important it is for countries to strengthen the organisation of their Veterinary Services. The Republic of Haiti is one of the developing countries with the most acute biophysical vulnerability. Over the years, it has experienced a large number of earthquakes, hurricanes, floods, droughts and epidemics that have further weakened a country with already scarce financial resources. However, Haiti is endeavouring to address biological threats by modernising its Veterinary Services and by implementing the animal health standards and guidelines of the World Organisation for Animal Health (OIE) for establishing resilient animal health systems.

The paper outlines a framework for shaping and prioritising improvements to investments in animal health systems in order to improve their sustainability. The framework includes financial inputs that can be separated between core investments and day-to-day expenditures. The latter financial inputs should differentiate between avoiding losses in production and reducing wider societal impacts such as negative implications for trade and the environment. Overall the framework provides information on the financial costs of the animal health system and the animal health outcomes that, if collected over time, will allow the efficiency of resource use across the system to be measured. It discusses an application of the framework using existing data, which highlighted problems with measuring and costing veterinary inputs, and with quantifying the range of outputs and the impact of veterinary activities. The paper recommends that the framework proposed is reviewed and compared with work that has been carried out on the human health accounting systems. A true application of the framework will require data sets that can differentiate between public-sector, private-sector and non-governmental organisation investments and the cost of day-to-day animal health goods and services paid by animal owners. Data sets are also needed on animal health outcomes in order to compare investments with animal health outcomes and thereby: demonstrate the success of previous investments, identify weaknesses in the investment profile and ensure that future investments sustain an animal health system, which functions well.

Animal pathogens attract attention in both the livestock and public health sectors for their impacts on socio-economics, food safety and security, and human health. These impacts are felt at the household, national, regional and global levels. Whereas the World Organisation for Animal Health (OIE) has identified 118 animal diseases as notifiable, based on their potential for impact on trade, there is a selected subset that have been classified as posing a greater threat to countries due to unique characteristics, such as being highly transmissible, spreading rapidly within and between countries, and requiring cooperation between several countries to control their spread or exclude them. While these 'transboundary diseases' are endemic in much of the world, particularly the developing nations, many countries are classified as disease free. Following the terrorist events of 11 September 2001 in the United States, a small group of zoonotic pathogens and a group of animal-specific pathogens (those that cause what are referred to as `high-consequence foreign animal diseases'), were classified as high-risk, biothreat 'select agents'. Rather than providing a comprehensive review of all animal pathogens, the authors briefly review the impact of these high-risk biothreat agents on animal health, the economy, food security and safety, and public health, using highly pathogenic avian influenza, foot and mouth disease and brucellosis as examples. They focus on the impact of these diseases in the context of high-income countries and low- and middle-income countries, comparing and contrasting their impact at the national and individual household levels.

Recent advances in the technologies for genomic sequencing and systems for handling and processing sequencing data have transformed bacterial genomics into a near-routine approach for both small- and large-scale investigations of infectious agents. Nonetheless, the application of genomics - especially largerscale studies - to animal infectious agents lags behind its application to human pathogens, despite the growing importance of many animal species as food sources. Assiduously conducted genomic studies offer major benefits, not merely by providing a detailed understanding of infectious agents but also through the exploitation of such findings to enable more accurate diagnosis, high-resolution typing and the development of improved interventions. The use of genomics for these and other purposes is likely to grow in future years and it must be anticipated that investigation and characterisation of important animal infectious agents will also gain considerable benefits. Using mainly animal pathogens as examples - including several infectious agents listed by the World Organisation for Animal Health - this paper provides a concise summary of some recent purposes and developments in bacterial genomics analysis.