In the 21st century, one of the potential consequences of climate change and free global trade is that animal and plant disease may pose increasing threats to our food supplies.

It’s important to understand the biology of the pathogens and pests involved, but it’s equally important to fully consider the human dimension, and the part that people and their behaviour play. That has been the basis of the Rural Economy and Land Use (Relu) Programme’s research on animal and plant disease, culminating in their latest briefing paper “Growing concerns: animal and plant disease policy for the 21st century (PDF)” .

Past policies

Even a cursory examination of government policy on disease reveals how unsystematic our present approach seems to be. Its origins are rooted in a different historical landscape and policy has grown up in a way that often seems illogical today.

One obvious example is the way in which animal disease is categorised as ‘exotic’ or ‘endemic’ and how this determines the political response. Public money and effort go into addressing -exotic- diseases such foot-and-mouth disease, while persistent infections such as Johne’s disease and infectious bovine rhinotracheitis are regarded as industry problems, attracting no compensation for farmers and no particular efforts to eliminate them.

Yet these endemic diseases are impacting significantly on food production, farmers’ profits and animal welfare. Research carried out by a Relu team at Warwick (PDF) has concluded that making more information on disease status and history available to livestock buyers could help to address this. For example, knowledge of the disease risks within the herd would have an effect on prices, giving the low-risk animal a higher value, and providing more incentive for farmers to eliminate disease.

The new Animal and Health Welfare Board for England needs to apply a systematic framework for risk and cost sharing that has the backing of stakeholders. At the moment, anomalies persist not only within the categorisation of animal disease, but between animal and plant disease.  These two factors still seem to be addressed within self-contained silos and carry very different consequences for farmers. There are surely many lessons, not only on cost and responsibility, but on other aspects such as disease risk management, that could be applied more widely between the animal and plant sciences.

All the right friends

One of the major findings of the Relu programme is how involvement of stakeholders can strengthen research and it can also make implementation of policy more effective.

The UK Government’s approach to the appearance of bluetongue in Britain in 2007 provides a good example of this. By working closely with the farming community they developed a control strategy, and a communications campaign implemented with help from veterinary and industry bodies raised awareness of the disease and the actions that needed to be taken.

But we really need an even wider engagement with society on these issues, even if it may sometimes make us feel uneasy. The 38 Degrees organisation for example, has an approach that some might regard as provocative on arguments such as bovine TB and the culling of badgers, but it does encourage involvement beyond the obvious groups.

There are new disease threats to our food all the time and the Relu report calls for a fresh approach from Government. Food is a concern for everyone and we should all be taking an interest in UK and world food security as price rise and supply become less secure.

About Wyn Grant

Wyn Grant is a graduate of the universities of Leicester, Strathclyde and Exeter. He joined Warwick University in 1971 and was chair of the Department of Politics and International Studies from 1990 to 1997.  In recent years he has been actively involved in research projects with members of the Department of Life Sciences at Warwick where he also teaches.  He is vice-president for Europe and Africa of the International Political Science Association.

The eradication of the long-feared cattle disease rinderpest, announced by OIE and FAO June 2011, is a momentous achievement. John Anderson has already written on this blog about the lessons learned during the rinderpest eradication programme, which I’ve also described on video.

If we can do it once, we can do it again; the only question is: what should be the next target?

For better or worse, many people in developing countries are dependent on livestock (sheep, goats and cattle) for their food, or for trade. Sheep and goats (or ‘shoats’ for short), in particular, form the mainstay of 100s of small-scale livestock keepers in rural communities, both for the milk they give and the meat they provide. Anything that improves the health of shoats reduces poverty and improves local health and welfare, which improves education levels, which again improves general welfare in a virtuous cycle.

The next target

One of the common diseases of shoats in developing countries is peste des petits ruminants (PPR), sometimes known as goat plague or kata. The disease was first described in West Africa, which explains the French name. PPR is now found in almost every country in Africa north of Mozambique, as well as the Middle East, the Indian subcontinent and through into China. It can cause high mortality – up to 90% – and its relentless spread seems unaffected by the current individual national attempts at mass vaccination which are not well integrated.

PPR is caused by a virus of the same group that causes rinderpest, and which shares many of the same characteristics: the virus spreads by close contact between animals (no insect or tick vector), it  has only one serotype (so a single vaccine protects against all known forms of the virus), and an effective vaccine and equally good diagnostic tests exist.

The basic tools that were used in the eradication of rinderpest are therefore in place to do the same job on PPR, and there is growing acceptance in international bodies such as the FAO that PPR eradication is possible and should seriously be considered. I discuss this in this short video too.

Achievable aim

That’s not to say we couldn’t make some improvements. There was never a DIVA vaccine (which allows one to Distinguish Infected from Vaccinated Animals) for rinderpest, and it meant it was never possible to keep scanning for disease while vaccination was going on. Several labs, including my own, are trying to make DIVA vaccines for PPR and I am sure one will soon exist which will help in the overall programme.

The experience of rinderpest eradication was that getting good local involvement in tracing disease was critically important, and kits are being developed that will allow sick animals to be tested for PPR in the field, allowing much more rapid disease identification and therefore more rapid responses. We also need to fill in the gaps in our knowledge of the distribution of PPR in both domestic livestock and wildlife because various species of wild goats and gazelles are susceptible.

None of these are insurmountable problems. There are a large number of livestock diseases for which we have no vaccine, like African swine fever, or which are too varied to be tackled with a single vaccine, such as Bluetongue, for which you need 25 different vaccines.

In contrast, ridding the world of PPR lacks only the willingness of the richer countries to fund the work and of the countries where it exists to work together to get the job done.

Perhaps the most important lesson that we learned in getting rid of rinderpest is that we can aspire to not just control and continuously try to manage a veterinary disease, but to remove it permanently on a global scale, thereby eliminating the threat as well as the cost of control from all future generations.

About Michael Baron

Michael Baron has worked on the basic biology of rinderpest and PPR at the Institute for Animal Health for the last 20 years. He is a self-confessed lab rat who would like to think that he can help the people who do the real work on controlling these diseases, out in the field, by providing some of the tools they need.

We now believe rinderpest has been eradicated from the world. When finally confirmed in 2011, rinderpest eradication will be the only disease conquered after smallpox back in the 1970s.

Rinderpest was one of the most devastating virus diseases of livestock known to man. Closely related to measles in humans, rinderpest (from the German ‘cattle plague’) has probably been around since before the birth of Christ and devastated European powers in the 17th century.

With a mortality rate of up to 90%, major epidemics in the late 1890s killed over 80% of African cattle and other wildlife in southern Africa. Along the Horn of Africa, an estimated one-third of the population of Ethiopia and two-thirds of the Maasai people of Tanzania died of starvation.

In the 1980s the virus struck again, killing an estimated 100M animals from Senegal to Somalia in Africa and from Turkey to Bangladesh in Asia. Economic losses totalled US$2Bn in Nigeria alone.

Coordinating action

Following the development of a live attenuated vaccine by British virologist Walter Plowright in 1962, early eradication efforts in the 1960s and 70s eventually stalled, but showed the war might be winnable.

As the UN’s Food and Agriculture Organisation (FAO) mobilised a new eradication campaign, the Global Rinderpest Eradication Programme, (GREP) in the 1990s, The Institute for Animal Health (IAH), Pirbright, UK, was designated the FAO World Reference Laboratory for rinderpest in 1994 and thereafter provided a global diagnostic service for all countries involved in the programme. This included rinderpest diagnosis, molecular characterisation, the provision of training and technical backup, and the production and quality control of diagnostic kits and research to further our understanding of rinderpest virus biology.

What lessons have been learned along the way?

The main factors in the success of GREP, from an IAH perspective, were the development of the right technology for field use in Africa and Asia, successful transfer of that technology along with technical backup, and the provision of standardised diagnostic kits that everyone could use.

Appropriate technology

The Plowright vaccine induces life-long immunity after a single vaccination, but only if the vaccine is maintained at the correct temperature before administration. The vaccine virus is rapidly inactivated at temperatures greater than 4C and so involved the strict use of a cold-chain. Seromonitoring was therefore essential to monitor the performance of the vaccination teams and to establish levels of herd immunity.

However, at the start of the Pan African Rinderpest Campaign and subsequently GREP, most laboratories were unable to carry out the virus neutralisation test to see if it had worked and mass testing was impossible.

To tackle this problem, IAH developed an indirect ELISA test (enzyme-linked immunosorbent assay) and underwent two-year field trials in Tanzania to make sure it worked under tough local conditions.

The test performed well and was later replaced with an improved test (a monoclonal antibody-based competitive ELISA) which gave greater specificity (>99.5%), sensitivity and reproducibility. It also greatly reduced the number of false-positive results which saved unwarranted and expensive field investigations. Furthermore, the use of this single test harmonised results and increased participants’ confidence when communicating during regional workshops.

Rapid diagnosis and detection was essential during the latter stages of the eradication programme. The development of a rapid pen-side test proved invaluable in countries such as Pakistan and Somalia and empowered the field veterinarians to take prompt action to stamp out the last remaining pockets of infection.

Technology transfer

The Rinderpest Laboratory Network established by the Joint Division FAO-International Atomic Energy Authority with the assistance of IAH Pirbright proved the ideal vehicle for technology transfer.

Annual co-ordination meetings were always linked to training courses and updates in diagnostic techniques, software programs or epidemiological strategies.

The success of this process is highlighted by the fact that the project holders are now regarded as experts in their own right and have assisted many other countries in establishing similar technology.

Standardised diagnostics

The provision of standardised quality controlled reagents played a major part in the eradication programme, and large batches of antigen and control sera were produced to minimise test variation between laboratories.

This was further enhanced by the use of a monoclonal antibody-based assay, and a single batch of monoclonal antibody was used for all the competitive ELISA kits produced.

External quality assurance panels showed a 98% agreement between laboratories in Africa; a much higher figure than that reported for HIV testing at that time.

Recommendations for the future

The strategy used for rinderpest eradication, although not applicable to all diseases, could be used as a blueprint for other diseases such as peste des petits ruminants (meaning ‘disease of small ruminants’, known as PPR virus).

Key factors for success include the availability of an excellent vaccine (which we have), secure long-term funding, the establishment of a Secretariat in FAO Rome as a global co-ordination unit, and evolution of the OIE Pathway to Freedom from Rinderpest guidelines which gave clear advice to all countries at each stage of the process.

However, let it not be forgotten that the drive and determination of a few key people was also essential to this remarkable success.

This story highlights the importance of continued support for applied, problem-driven research in agriculture and food security.

Addressing significant animal health problems through appropriate research and development – allied to excellent technology transfer and empowerment of local scientists – has played a key role in this major achievement.

About John Anderson

John Anderson joined the Institute for Animal Health (then the Animal Virus Research Institute) in 1968 as a technician in the World Reference Laboratory (WRL) for foot-and-mouth disease (FMD) before being seconded to Nairobi, Kenya, in 1971 to work on FMD carrier status in local cattle and the role of wildlife in FMD epidemiology.

He returned to IAH Pirbright in 1977 and worked on FMD, rinderpest and bluetongue viruses and was designated Head of the WRL for rinderpest in 1994 where he developed the indirect and competitive ELISAs and pen-side test for rinderpest which were used throughout the Global Rinderpest Eradication  Programme.

He was in charge of the serological testing during the 2001 FMD outbreak in the UK and was awarded the MBE for Services to Animal Health in 2003. In 2006, he was appointed Acting Head of IAH’s Pirbright Laboratory until his retirement in 2008.

Tracking plant pathogens is a vital part of agro-economic development, says Maurizio Vurro.  

As with human and animal diseases, the emergence or re-emergence of plant diseases is often due to man’s activities – a consequence of mass tourism, global trade, or changes to farming practises or the environment. 

Although our ability to diagnose and control diseases is greater than in the past, emerging infectious diseases (EIDs) are still able to cause tremendous crop losses. In developing countries in particular, the economic and social impact is often underestimated as I, with colleagues, recently discussed in the journal Food Security. 

Cassava Mosaic Virus Disease, for example, is capable of reducing yields by 80-90% and suspends cassava cultivation in many areas of East Africa. Striga hermonthica, a parasitic weed, affects cereal cultivation across at least 5 million hectares in sub-Saharan Africa. And the rust fungus Ug99, which has overcome resistant varieties, has spread from Uganda and threatens most of the wheat-growing countries in the world. 

Countries with limited resources are threatened when pandemics occur on important food crops, such as Xanthomonas Banana Wilt, a bacterial disease that affects the food security of 70M people in Uganda. This kind of low crop productivity contributes directly to malnutrition, and indirectly to the spread of human diseases and the collapse of the environment because poor rural areas are abandoned with a concomitant phenomenon of urban overcrowding. 

In developing countries there are clear links between food insecurity and institutional fragility. The 2008 food crisis highlighted the acute vulnerability of net food-importing developing countries in the sub-Saharan Africa. In the past two decades, those countries have reduced investment in rural areas, exacerbating migration to cities and increasing the demand for food imports. This vicious circle further undermines the capacity of agriculture to produce the required food and increases dependence on food imports. 

Hunger is further worsened by the lack of public interventions, institutional fragility, limited public investments in rural areas, political and administrative chaos, war and local guerrilla action, and climate change. In this context, the effectiveness of humanitarian aid, in the absence of appropriate conditions to start productive activities, is largely frustrated. 

Surveillance of EIDs is thus crucial for developing countries’ agricultural self-sufficiency and wider social economy, but these technologies are often expensive and require technical preparation, economic investment and personnel. Given the cost, many developing countries have limited control systems; nor can they acquire and update lists of emerging pathogens within their borders. 

The consequence is that many diseases in developing countries simply spread without being recognized and monitored. 

In Western countries surveillance systems are easier to deploy because of existing community networks, there are more economic opportunities, and greater availability of the necessary technologies at affordable prices. Furthermore, in developed countries there are social safety nets to support those most affected; food reserves that limit the risk of famine; research systems and technical support services that enable management of those diseases or diversification to alternative crops; and warning systems that allow the prompt application of control measures. 

Similar systems must be urgently established in developing countries to avert the socio-economic disasters that can be caused by plant diseases. The development of a large EID-monitoring organization on a territorial basis, with clear roles and accountabilities, is of utmost importance.

About Maurizio Vurro

Maurizio Vurro has been a senior researcher at the Institute of Sciences of Food Production, National Research Council, since 2001. His main scientific interests are the use of microbes and natural metabolites in biological control, in particular against weeds. He recently led the project ‘Enhancement and exploitation of soil-biocontrol agents for bio-constraint management in crops’ within the 6th EU Framework Programme and is the author of more than 70 articles in scientific journals, three books, and seven book chapters.

Why is such a policy important?

Because for developing countries, the consequences of insecure food supplies are severe and undermine development and progress. 3 out of 4 people in developing countries live in rural areas, and most depend on agriculture for their livelihoods.

The UN’s Food and Agriculture Organisation says developing countries may experience a decline of between 9-21% in overall potential agricultural productivity as a result of global warming.

When crops or livestock are affected by climate change impacts or other factors, such as disease, the effect on local families, communities and the wider country is devastating.

Lack of available produce means less food and less income for small-holder farmers and their families. Consequently, cases of malnutrition rise – particularly in children – resulting in potentially long-term health problems which inhibit people’s capacity to attend school or earn a living.

The food crisis of 2008 caused an additional 110M people to suffer from hunger and permanent damage to 40M malnourished children.

We have only 5 years left until the 2015 deadline to achieve the Millennium Development Goals and the first of these, to reduce the proportion people who suffer from hunger, is veering further off target thanks to the food crisis, global economic crisis and climate change impacts. 

But UK science can help.

The UK has historically been seen as a world leader in both research and knowledge exchange in development agriculture. As detailed in the UK Agri-Food Science Directory, we have at least 280 agricultural and food-related research organisations and 5 research councils committed to research that is either directly relevant or applicable to developing countries.

Take the near elimination of rinderpest as an example. A major outbreak of this infectious viral disease in 1982-1984 had a devastating impact on Africa’s livestock, causing losses valued at over £300M. UK scientists have been behind the development of a vaccine that will soon result in an announcement of the eradication of the disease.

Links between development funders and UK researchers are strengthening. The Department for International Development (DFID) has made agricultural research a priority and will now double its support over the next 5 years from £40M in 2009 to £80M per year by 2014.

New research programmes between DFID and BBSRC like Sustainable Agriculture Research for International Development (SARID) and its follower CIDLID (Combating Infectious Diseases in Livestock for International Development), supported by the Scottish Government, are opening the door for more development-focused agricultural science.

And international funders like the Gates Foundation are backing more UK research projects on development agriculture, such as the Africa and Europe: Partnerships in Food and Farming project at Imperial College, London. 

The launch of the UK Cross-Government Food Research and Innovation Strategy this month is another demonstration of the UK’s commitment to food-related research.

It’s through this type of coordinated, collaborative approach to food and agricultural research, combined with the proposed new plans for an EU policy on food security and developing countries, which can help steer the Millennium Development Goals back on track.

About Dr Andrée Carter, Director of the UK Collaborative on Development Sciences (UKCDS)

Dr Andrée Carter is the Director of the UK Collaborative on Development Sciences (UKCDS), a collaboration of research councils, government departments and charitable foundations working to maximise the impact of UK research on international development.

Originally trained as a soil scientist, Dr Carter has worked closely with UK and EU governments, research and corporate organisations to protect and improve the quality of the environment and those dependent on it for their livelihoods.  

She was previously the Director of Science and Environment in ADAS UK Ltd., an agricultural and environmental research consultancy and prior to that worked at Cranfield University.

Contact details

Dr Andrée Carter, Director
UK Collaborative on Development Sciences
Gibbs Building
215 Euston Road
London
NW1 2BE

Tel: 0207 611 7330
Email: a.carter@ukcds.org.uk

Threats from diseases are predictably unpredictable – think BSE, foot-and-mouth disease, and the avian and swine influenzas. 40 new species of pathogens have been recognised in livestock and man during the past 25 years; most are RNA viruses but diseases caused by prions, bacteria, rickettsia, fungi, protozoa and worms are also represented.

The recent incursions of Bluetongue (BT) virus into northern Europe have provided an effective reminder that livestock can quickly become exposed to a new and serious disease introduced because of changing weather patterns. In this case, a warming climate across northern Europe created conditions favourable for the spread in sheep and cattle of the BT virus typically found in Africa and the Mediterranean. In 2008 up to 10% of the sheep died in some European countries and only the UK’s introduction of a national plan for vaccination prevented similar establishment and spread of the disease.

In addition to completely new disease threats such as bluetongue, the livestock sector has to contend with re-emerging pathogens that were once thought to be controlled, only for them to reappear in more aggressive or virulent forms that are no longer well controlled by existing vaccines.

A classic example is presented by Marek’s disease in poultry. This herpes virus produces rapid-onset tumours in the heart, ovaries, testes, muscle tissue and lungs (with mortality rates as high as 80%) and continues to change in virulence such that every decade or so a new vaccine is required.

Let’s take a specific look at poultry production. The UN’s Food and Agriculture Organisation (FAO) regards poultry products as a key component of growth in food production. An estimated 51Bn chickens are now produced each year worldwide, of which 46Bn are broilers (for meat) and 5Bn are layers (for eggs). Developing countries share of world poultry meat consumption rose from 43 to 54% between 1990 and 2005, with major contributions from east and southeast Asia, Latin America, China and Brazil. The FAO estimates that production and consumption of poultry meat will increase by around 3.6 percent per annum from 2005 to 2030.

The poultry sector is especially dependent up on the availability of vaccines and several diseases, if uncontrolled, have the potential to seriously derail the productivity of the poultry industry at a time when in some parts of the world up to 1M birds are reared together in order to meet increasing demand.

The sheer size and scale of poultry industry presents a great strength for the efficient production of meat, but a potential weakness if the control of devastating diseases such as Marek’s disease ever becomes unachievable.

The production of poultry and livestock is clearly ever dependent upon continued scientific innovation to deliver effective strategies for the control of infectious diseases. My task is to ensure that a public sector-funded institution such as the Institute for Animal Health is able to provide a network of global intelligence on the spread of pathogens, assess risk to specific countries, and deliver effective vaccine strategies to control new and existing livestock pathogens which distinguish between animals that are infected naturally or vaccinated deliberately.

It is sometimes tempting to think that the availability of a vaccine delivers a permanent solution; it is but a lull in the arms race between host and pathogen.

The livestock industries must therefore contend with a succession of emerging and re-emerging pathogens at a time when world population is increasing and meat consumption rises in the world’s most populous countries.

Finally, there are now fewer ‘easy wins’ available to researchers to develop vaccines at a time when consumer resistance to the use of drugs (especially those given in-feed) is changing. Unfortunately, the rate at which the commercial animal sector is able to introduce new drug therapies and vaccines might slow further because of increasing costs of both research and development, and of getting new products into the field.

About Professor Martin Shirley, Director of the Institute for Animal Health

Martin Shirley started his career at the Houghton Poultry Research Station (HPRS) as a junior technician upon leaving school in 1967. Ten years later, he returned to HPRS and was awarded a PhD by Brunel University for research on protozoan parasites from the domestic fowl.

Martin is now a world authority and author of more than 150 scientific papers and articles on coccidial parasites of poultry.

Martin was appointed Director of the Institute for Animal Health in July 2006 and his awards and honours include Honorary Professor at the Royal Veterinary College (2007) and Research Medal of the Royal Agricultural Society of England (2002).

Contact details

Professor Martin Shirley, Director
Institute for Animal Health
Pirbright Laboratory
Ash Road
Pirbright
Surrey
GU24 0NF

Tel: 01483 232441
Email: martin.shirley@bbsrc.ac.uk