Memorandum submitted by the Institute for Animal Health (SFS 46)
eggs and dairy products are a major part of the
disease scenarios are expected with changing
Control of disease is absolutely essential for some sectors of livestock production, principally the intensive production of broiler chickens. In the absence of effective vaccines or drugs, the major pathogens of poultry would be uncontrolled, cause high rates of mortality and prevent large-scale poultry production.
Defra must continue to invest in the control of important livestock diseases, be prepared to ensure the long-term availability of key scientific and technical skills and adequately support the provision of key infrastructure.
Defra must continue to provide leadership in research for better control of disease. Current funding models within the UK for this topic are 'fragmentary' and may be dependent upon commercial or academic considerations yet the current statutory obligations of Defra for disease surveillance dictate a leadership role and much ownership of the agenda.
Given the national importance of diseases such as bovine tuberculosis, foot-and-mouth disease, bluetongue and avian influenza, Defra must also develop a stronger leadership role in the communication of science to a lay audience.
value to the
impact of infectious diseases is considerable and directly accounts for a loss
of around 20% of total production through a reduction of the value of livestock
(poorer quality), less efficient rates of conversion of food to meat, less
optimal weight gains, increased costs of production associated with use of
vaccines and other medicines and poorer welfare. In addition, diseases such as
bovine TB (bTB), bluetongue, avian influenza and foot-and-mouth disease (FMD)
have impacts on the social fabric of the
seeking to secure food supplies up to 2050, an important part of the
• There will be a continuing need to protect animal health and welfare against new and variant pathogens.
diseases will emerge and re-emerge with changing
• Infectious diseases will remain a global problem that is exacerbated by changes in climate, demography, globalisation, trade, animal movements, land use and diversity of livestock products.
• There will be increased threats to human health from zoonoses.
will be greater risks associated with bioterrorism to
• There is already now a reduced availability globally of drug-treatment for food-producing animals.
rising global population, together with the factors above, increases further the
need to protect
Defra investment will be necessary to help support a vision for the future production of disease-free livestock that contributes to ensuring the delivery of a pipeline of new and increasingly sophisticated control measures in collaboration and alignment with the best commercial companies. Defra and other funders, such as BBSRC, must continue to work closely together and, in turn, help create the best working environment for scientific collaborations with the commercial sector.
control of disease in major livestock species, it is clear that vaccination is
becoming the approach of choice. The poultry sector, especially, relies heavily
on vaccines and given the importance of this sector to the UK
2. A NEED FOR CONTINUED INVESTMENT BY DEFRA IN TO DISEASES OF LIVESTOCK: SOME EXAMPLES
A continued need for Defra to invest in relevant, longer-term research
Chicken meat and eggs comprise a major part of the
Chickens (broilers) reared commercially for their
meat are housed in large numbers on the ground and at high stocking densities.
against many pathogens is an integral part of the poultry industry and it is
unlikely that poultry production on the current scale would be achievable if
just one of the major diseases were to become uncontrollable. Many pathogens of
poultry evolve with time, through the selection of genetic variants which can
lead to dramatic changes in their virulence and pathogenicity; the sector has
also had to deal with incursions of entirely new diseases on occasion. To
illustrate that continuity of current poultry meat supplies cannot be taken for
granted, reference can be made to Marek's disease, a highly contagious
neoplastic disease caused by Marek's disease virus (MDV). This disease can
cause devastating losses through high mortality and morbidity and the
A critical point about the example with Marek's diseases is that the relationship between the host (chicken) and the pathogen (Marek's disease virus) can be viewed as a classic "Arms Race" in which the continued evolution of the pathogen through natural genetic mutation enables the selection of viruses that can overcome an intervention strategy such as vaccination. Thus, whilst vaccines may "win" for a period of time, a rapidly mutating pathogen that cycles rapidly through livestock reared under highly intensive conditions of husbandry has the potential to become the ultimate "victor". History indicates that, in the case of Marek's disease, perhaps five or more new control measures will be required by 2050
3. CATTLE AND SHEEP PRODUCTION
A continued need for Defra to invest in relevant, longer-term research and science communication
In view of the changing livestock diseases and patterns of disease experienced in the UK, increasingly as a result of climate change, Defra will again need to continue to support a range of scientific research activities with a preparedness to invest in the infrastructures necessary, be they facilities, scientific and technical experts or tools and reagents, to ensure that the UK is adequately equipped with the resources necessary to control, contain and eradicate diseases as necessary.
is now the prospect that diseases currently given the status of "exotic" to the
dairy sector provides a good example of the opportunity that exists for
o Ongoing changes in the UK dairy industry, which include reduction in herd numbers, increase in herd sizes, geographic concentration of dairy herds and small profit margins leading to rationalisation of husbandry, are likely to have an impact on the way animal diseases are spread within the dairy cow population and on the way diseases and their impact are viewed and dealt with by the industry.
o Establishing a greater farm-level biosecurity culture in the farming sector would improve control of the spread of endemic diseases and better prevent incursions of exotic diseases, but farmers and others within the dairy industry seem reluctant to pursue this approach.
o There is a need to understand more fully the reasons why farmers adopt or resist disease control mechanisms. A key factor in the adoption of disease control measures is the communication of scientific advice and the relationship between scientific experts and the lay public.
o New forms of engagement between expert and lay actors (e.g. participatory and deliberative experiments) may foster better uptake of science-based disease control measures by resolving conflicts between different perceptions of knowledge and best practice.
o A key requirement is, therefore, to understand how disease control advice is communicated to farmers and to identify the main conflicts between scientists, veterinarians and farmers in developing disease control solutions.
examples of endemic disease with increasing prevalence in the
o The immunosuppression caused by BVD may have two outcomes in relation to bTB
§ some cases of bTB may not be revealed by testing; and
§ subclinical cases of bTB may be exacerbated by unhindered dissemination of tubercle and become clinical "open" cases allowing spread of infection to other cattle and humans.
o The presence of these two diseases in British cattle may, either singly or in combination, be affecting the viability of dairy farms, thus having a major impact on rural communities and on the dairy product and live animal value chains, thus affecting the wider economy. bTB is also a zoonosis and an increase of bTB in cattle is causing a risk of a corresponding rise in the number of human cases.
o In other countries,
both within and outside the European Union, BVD and bTB have been eradicated,
or there are on-going eradication programmes.
By not following this example and eradicating these diseases, the
o During the next four decades, Defra has an opportunity to work with others to eradicate some important disease and, in so doing, ensure that cattle production is optimised further.
Institute for Animal Health