Livestock Disease

A. Abstract The 2001 Foot and Mouth Disease outbreak cost the UK £6-9 billion. In 2010-2011, the government spent £91 million compensating farmers for bovine TB. The government is now considering proposals for sharing costs and responsibilities for preventing and controlling disease with the livestock industry. This POSTnote examines disease threats to UK livestock, outlines prevention and control measures, and looks at factors likely to contribute to future disease. B. Background Population growth, rising affluence and urbanisation are factors driving expansion in the livestock sector. It is estimated that global population will rise from nearly seven billion in 2011 to over nine billion by 2050. Over the same timeframe, per capita meat consumption is predicted to rise from 32 kg a year to 52 kg a year. This increased reliance on livestock has come at a time when the UK faces a heightened threat of livestock disease. Moreover, this also presents substantial challenges to food security in the future. Globalisation, animal movements and trade coupled with climate change and economic recession all have the potential to reduce capacity to prevent and control disease. Three main classes of animal disease threaten the UK: ‧ Those that are not usually present in the UK and which can affect animals and humans, such as Avian Influenza; ‧ Those that may or may not cause clinical signs in animals but cause disease in people, such as Salmonella and E. coli; ‧ Those that do not present a significant public health risk but affect animal welfare, productivity and profitability, such as Bovine Viral Diarrhoea. C. Prioritisation of Livestock Disease Several factors define the importance placed on a particular disease. Defra uses the following four criteria to prioritise allocation of Government resources to deal with animal health issues. ‧ To protect public health: two thirds of known human diseases are zoonoses (i.e. transmissible between animals and humans). For example, Campylobacter and Salmonella transmitted from poultry or pigs to humans are major public health concerns; ‧ To protect and promote the welfare of animals: animals are protected under UK animal welfare legislation. “Freedom from pain, injury and disease” is one of the Farm Animal Welfare Committee’s ‘Five Freedoms’; ‧ To protect the interests of the wider economy environment and society: losses in farm production combined with disruption to markets and international trade pose risks to livelihoods. Loss of income from tourism during a disease outbreak can also affect a wide range of business. ‧ To protect international trade: during a notifiable disease outbreak, EU controls are enforced to ban the export of live animals and animal products. This may have an impact on international trade for months or years and can reduce future trust in UK produce. D. Prevention and Control Based on the principle of “Prevention is better than cure”, EU Animal Health Strategy outlines both prevention and control measures to be implemented during a disease outbreak. Disease Prevention 1. Surveillance Surveillance provides early warning and prompt detection of livestock disease threats, together with analysis of the way diseases spread. Surveillance within the UK depends on disease identification and reporting by livestock keepers and veterinarians and enables disease patterns to be monitored. In the wake of the 2001 Foot and Mouth Disease (FMD) outbreak, monitoring of international disease at Defra was intensified. Defra uses official disease reports from the OIE, EU, Foreign and Commonwealth Office, UK laboratories and research articles to monitor disease risk and trends in new and emerging diseases. It produces monthly reports outlining the main exotic disease threats and monthly and quarterly reports on the domestic disease situation. 2. Control at Source Livestock disease is a global problem. Emerging diseases, changing patterns of disease and increasing globalisation mean that global disease threats also put the UK at risk. Control, and ultimately eradication, of diseases elsewhere in the world have the potential to protect animals in the UK. For example, in 2004, the Global Rinderpest Eradication Programme (GREP) was launched by the Food and Agriculture Organisation of the UN and in June 2011, the UN announced that the goal had been achieved, with now GREP’s activities focusing on surveillance systems to prove the absence of the disease. 3. Biosecurity Good biosecurity means ensuring good hygiene practices are in place. It is a vital part of keeping disease away from livestock, preventing any spread between livestock and, for zoonoses, minimising the transfer to humans. Biosecurity must be maintained in farms, markets, during transport and at slaughter. 4. Traceability Being able to trace livestock movements enables disease spread to be monitored. The EU is now implementing a system across member states requiring all sheep 12 months or older to be electronically tagged. The introduction could improve efficiency and lead to an integrated EU electronic system. However, poultry are not currently covered by such arrangements. 5. Import/Trade controls Legal and illegal imports of live animals and animal products are potential sources of disease risk. Non-animal products can also be potential. For example, imported car tyres can harbour mosquito larvae. 6. Wildlife Control/Management Seventy-two percent of diseases transferred between livestock and humans are also present in wildlife. Vaccination and culling of wildlife can be used to prevent the spread from wildlife to livestock. For example, previous trials showed that culling badgers reduces bovine TB incidence, although culling has been opposed by some animal welfare and conservation groups. 7. Vaccination Vaccines stimulate an immune response to protect animals against later infection with a specific disease. They are widely used to control endemic diseases such as Salmonella in poultry. Potentially, vaccines could also be used to prevent diseases such as bovine TB, although no effective cattle vaccine is currently available for this disease. 8. Husbandry/Production System Animals that are cared in accordance with existing welfare standards are less likely to contract or spread disease and tend to be healthier. Different production systems are associated with differing disease risks. For example, intensive, indoor systems can significantly reduce contact with certain diseases. However, stress associated with intensive production may increase susceptibility to disease and its subsequent spread. Conversely, animals housed in extensive systems might be more likely to come into contact with disease, but the risk of contracting and spreading it may be lower. 9. Genetic Modification and Cloning Genetic modification (GM) could be used to introduce novel genes that confer resistance to infection. For example, in 2011 scientists at the Roslin Institute used GM to prevent chickens transmitting Avian Influenza. Animal cloning technology has been used to extend animal breeding and production potential and may in future be able to clone animals with reduced susceptibility to disease. Some consumer groups have expressed safety concerns about GM and cloned animals, whereas other groups oppose such procedures on animal welfare ground. Within the EU, food from cloned animals must be authorised under the EU Novel Foods Regulation before it can be sold. However, there have been no such applications in the EU to date. In Nov. 2010 the Advisory Committee on Novel Foods and Processes concluded that meat and milk from cloned cattle and their offspring were unlikely to present a food safety risk, but noted that consumers may wish to see effective labelling. In Mar 2011 EU negotiations on amendments to the novel foods regulations broke down but proposal of new legislation on cloning is likely in the future. Disease Control In addition to the existing control system, following a disease outbreak additional measures can be implemented to control its spread. For some notifiable diseases, the European Commission prohibits export of animals and animal products from the affected species until disease-free status has been achieved. 1. Antimicrobials Antimicrobials (or antibiotics) can destroy or inhibit the growth of bacteria. They may be used both to treat disease in infected animals and to prevent disease in those at risk or known to be susceptible. While the controlled use of antimicrobials is necessary to limit infections in animals, excessive or inappropriate use may contribute to the development of antimicrobial resistant organisms, compromising the effectiveness of related medicines in humans. 2. Culling of Livestock Culling is another disease control measure. In general, infected animals and those that have been in contact with the infected ones will be slaughtered and disposed of. Accurate surveillance information about the geographical location of disease and its spread can be used to construct models to inform culling policy. 3. Emergency vaccination Vaccination can be used to control an outbreak of disease once it has been detected. For example, it was successfully used to control a UK Bluetongue outbreak in 2007 and Defra is currently trialling a badger vaccine as a control measure for bovine TB. Vaccination has its drawbacks, such as few vaccines give 100% protection and vaccines have not yet been developed for all diseases. For some diseases, use of vaccination during an outbreak can make it difficult to distinguish between animals that have been vaccinated and those that are infected. This makes it hard to ascertain when the disease has been eliminated and disease-free status has been achieved. The development of DIVA (Differentiating Infected and Vaccinated Animals) tests is ongoing and is likely to make vaccination a more attractive option. 4. Animal Movement Controls When a contagious notifiable disease outbreaks, preventing the movement of animals between farms, markets and slaughterhouses can limit its spread. Planning A risk management approach can be used both to prevent disease and to manage outbreaks. Aspects to be considered include environmental conditions, how the disease is spreading, how it is transmitted and any vectors that may be involved. While government strategy emphasises disease prevention, it also incorporates lessons learned from previous outbreaks into plans for managing future outbreaks. For example, vaccines would be seriously considered for any future FMD outbreak. The government has taken measures to ensure vaccines would be available, if needed. Defra recently published a new Contingency Plan for Exotic Notifiable Diseases of Animals. It outlines the roles and responsibilities of a wide range of bodies including central government and its agencies, local government, non-government organisation, animal keepers, veterinarians and the police. E. Responsibility and Cost Sharing Currently the cost of compensating farmers for animals/products compulsorily destroyed in a notifiable disease outbreak is covered by the government. The Animal Health and Welfare Strategy proposed that responsibilities and costs of livestock health and welfare should be balanced between industry and taxpayers. In 2011 Animal Health and Welfare Board for England was established and is expected to discuss future decisions on cost sharing in the future. F. Factors Influencing Future Disease Threats Strategic Responsibilities Disease control and prevention is a responsibility shared commonly between relevant stakeholders. The consensus is that the government should retain responsibility for funding research and development, disease surveillance and maintaining a competent veterinary service for the prevention and control of exotic disease. Responsibility for livestock health lies with livestock keepers and the livestock industry. Indentifying early signs of disease remains the responsibility of the livestock keeper, and subsequently the veterinarians. Compensation for endemic disease could be replaced with insurance taken out by livestock keepers against animal losses. Veterinary Supply Veterinarians are placed to promote livestock health and to advise owners on disease prevention. Their ability to recognise the early signs of endemic, exotic and emerging diseases will depend on the extent of their training within this field. BVA voiced their concerns that the supply of veterinarians with experience of farm animal medicine may be threatened by the lack of profitability in the farm animal sector, coupled with increase in the cost of university education. In response to this, Defra commissioned a report on this issue and it concluded that there were no foreseeable problems with the supply of farm animal veterinarians. Climate Change Climate change may result in the emergence of new diseases. Higher temperatures and variable precipitation may lead to new transmission mechanisms and an increase of vector-borne diseases and parasites. This puts the onus on surveillance and training of farmers and veterinarians to identify new diseases. Intensification and Food Security With the increase of global population, combined with pressure caused by consumer expectations of cheap food, livestock production systems are being further intensified. A recent government project has called for “sustainable intensification”. Pressures to intensify livestock systems could themselves threaten food security if they increase the likelihood of a serious disease outbreak. Consumer Behaviour Following a long-term decline in food prices, recent years have seen food prices increase again. Between 1975 and 2007, food prices fell by 32% in real terms but have risen by 26% in the four years since 2007. Veterinary and animal welfare groups are concerned that pressures to keep food prices low might adversely affect standards of animal health and welfare. However, the success of food assurance schemes that set standards for hygiene, animal welfare and environmental protection suggests that higher welfare products are a priority for consumers. G. Review ‧ Livestock disease affects the economy, animal welfare, the environment and public health; ‧ Current policy covers disease prevention and control, with the majority believing that prevention is better than controlling disease outbreaks; ‧ An increasing global population stimulates demand for meat consumption and such development is likely to lead to growth in the livestock sector; ‧ Intensification, climate change and increasing globalisation and trade are likely to increase disease risks; ‧ Proposal of a new system of responsibilities and cost sharing promotes sharing of responsibilities between farmers and government.
Last Modified : 2015/06/24