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Livestock Health, Management and Production › Animal Health Management › Managing animal health for trade

Animal Health ManagementManaging animal health for trade

Author: Dr Mary-Louise Penrith.

Licensed under a Creative Commons Attribution license.

INTRODUCTIONAfter completion of this module, students will be expected to understand how animal diseases influence trade in livestock commodities and understand and explain the role of animal health managers in supporting this trade. They should be able to apply the knowledge gained to formulate animal disease control strategies that are functional and appropriate for the circumstances under which they will be implemented, maintaining the focus on the objectives of animal health management and disease control.

Livestock commodities (i.e. fresh or frozen meat, fresh eggs and milk, raw hides and any other derivatives that have not undergone further processing) including live animals are traded both nationally and internationally. International trade in livestock commodities is covered in depth in a series of dedicated modules. The focus of this module is the impact that animal diseases can have on trade at all levels and the approaches to managing them to minimise their impact.

Fresh milk is a livestock commodity

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http://preview2.bluematrix.co.za/education/livestock/animal-health-management/ahm-managing-animal-health/2012


http://creativecommons.org/licenses/by/3.0/


Fresh meat is a livestock commodity

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Animal health management for trade is concerned with ensuring that traded livestock and commodities derived from livestock are safe in terms of transmission of diseases to animals and humans. It is also concerned with supporting producers to ensure that there is a steady supply of healthy animals available for trade, and is supported by both public and private veterinary service providers. Services can range from primary animal health care and routine surveillance for controlled diseases to herd health programmes aimed at optimising and monitoring health and production to ensure consistency of quality as well as supply. Primary animal health care is often supplied, especially in remote rural areas, by community-based animal health workers (CAHWs) trained and equipped to undertake basic activities like parasite control, vaccination, and first aid for minor injuries and ailments. To an extent the level of animal health service provision will depend on the demands and value of the market, but in the end it is the responsibility of animal health managers to try to ensure that food of animal origin offered for sale for human consumption is safe and wholesome, whether the food is destined for the highest priced export markets or the next door neighbour.

To provide background for animal disease control in the context of trade in livestock, the first section deals with trading of live animals and commodities derived from animals (as opposed to processed products) insofar as it is affected by infectious diseases. More detail about marketing and trade is provided in modules dedicated to the subject.

The second section considers approaches to controlling endemic and epidemic transboundary diseases in the context of the country’s different production systems.

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BACKGROUND TO TRADE IN LIVESTOCK COMMODITIESLive animals

Live animals pose the greatest risk for transmission of infectious diseases. Cross-border trade in live animals therefore usually involves some formalities that at the least would be a veterinary certificate of health but normally include quarantine requirements as well. However, in many countries moving animals from one area to another also involves formalities. This may be to maintain zones free of particular diseases and to reassure trading partners that this is being done correctly. For example, South Africa requires internal movement controls to ensure that cloven-hoofed animals are not moved from the foot and mouth disease (FMD) protection zone around the Kruger National Park to the rest of the country and that pigs are only moved from the African swine fever (ASF) control zone in the north-eastern part of South Africa (mainly Limpopo province) from accredited farms within the zone to designated abattoirs outside the zone. Even countries without designated free zones may require movement permits in order to keep track of animals and to prevent spread of diseases from one part of the country to another.

Classification and description of livestock marketing systems

Live animal markets(“wet” markets), shows, fairs, auctions

Agents and speculators

Sale at point of slaughter (abattoir)

Retail outlets other than livestock markets

Private sales – home, roadside

Internet auctions

Import and export marketing agents and systems

Challenges for animal health management

With the presumed exception of internet auctions, which offer a sophisticated way to avoid unnecessary transport of animals and contact between animals of different origin, marketing animals can pose a health risk. Even animals bought over the internet might pose a risk if they are not transported in the correct way.

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Live animal market, Port Bouet, Abidjan, Ivory Coast

Live pig market, Assomada, Santiago, Cape Verde

Live animal markets or the equivalent (show, fairs, auctions), where large numbers of animals are brought together under unavoidably stressful conditions, clearly pose a level of risk of disease

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transmission that many regard as unacceptable. The H5N1 avian influenza pandemic has led to at least temporary closure of live poultry markets in some countries, for example China, since it was evident that infected birds were being offered for sale and that such markets could become focal points for spread of infection. In developing countries especially, when animals start to sicken or die and the owner realises that he has a serious disease in his animals the tendency is to sell off animals as quickly as possible to limit damage. This has been cited as a major reason for the spread of ASF in Nigeria and has certainly contributed to the fact that the disease has now become endemic in that country. This tendency is exacerbated by disease control programmes that involve compulsory culling and disposal of animals without adequate compensation. Nevertheless, under conditions where live markets offer the only alternative to even higher risk sale procedures, they present the veterinary authorities with an opportunity to perform inspection of the animals offered for sale and to take the necessary steps should diseases be detected. The key to mitigating the risk of live animal markets is that as much veterinary supervision as possible should be supplied, that the size of the market should be manageable, that the facilities should be such that reasonable separation of lots from different producers is achieved, and that detailed records of animals offered for sale are kept to permit rapid tracing to farms of origin if any outbreaks do occur.

Sale at point of slaughter, i.e. at an abattoir or other area designated for slaughter of animals, should be safe, as such places can and should be regulated by the veterinary public health authorities. However, abattoirs have been incriminated as sources of disease, owing to practices such as the sale of live animals for home slaughter or for purposes other than slaughter. It was suspected that an outbreak of ASF in Nairobi in 1994 may have originated from pigs brought from an area close to the border with Uganda to an abattoir in Nairobi and being sold live to clients instead of being slaughtered. There is also a possibility that animals in the incubatory phase of a disease may show no clinical signs or lesions at inspection but infected product will be released to the market. To prevent this happening in the case of an asymptomatic bovine infected with bovine spongiform encephalopathy (BSE) being slaughtered, there is a requirement for the removal of specified risk materials (SRMs), which include tonsils, distal ileum, brain, eyes, spinal cord, skull and vertebral column. The rest of the carcass is safe, although animals known to pose a high risk (e.g. old dairy cows born before the feed ban) are not passed for human consumption. Lymph node removal is generally considered to reduce risk of disease transmission and may be recommended for other diseases as well, e.g. FMD. Sale of live animals through retail outlets other than livestock markets is generally confined to companion animals including birds that are sold through pet shops. Particularly in the case of imported birds and reptiles, it is important that the veterinary authorities ensure that the proper quarantine procedures have been complied with before these animals are disseminated to the public.

Private sales and sales through agents are activities that are often impossible for the veterinary authorities to monitor, and the risk can therefore be high. Professional agents who work under

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contract to their clients are unlikely to place their livelihoods at risk by breaking the laws pertaining to animal movements and sales. On the other hand, livestock speculators are rife, particularly in the rural areas in the developing livestock sector. They provide a means of selling animals beyond the local market for producers who have no transport to carry animals to the distant urban markets, and therefore make an important contribution to the economy of such areas, even if the prices offered are frequently less than fair. However, their role in the spread of disease is undisputable, since they move from one producer to another and can also move infected and sick animals to new areas, selling them off on the way if they look as if they will not survive the journey.

Sales transactions between private individuals probably pose the lowest risk, provided that both parties are properly informed and that sick animals are not sold or bought. Purchase of animals directly from breeders is recommended as a safe way to acquire animals, provided the breeders are reputable and their facilities are visited by veterinarians (private or state) on a regular basis. In the informal livestock sector breeders may be less reliable. As previously indicated, during disease outbreaks that result in heavy mortality the temptation to sell off animals that appear healthy but may be incubating disease is extremely high, and the danger of this practice must be a prominent part of farmer education as well as public awareness programmes.

Illegal roadside sale of pigs during an African swine fever outbreak, Volta, Ghana

Trade in commodities derived from animals

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Trade within countries

At local level, apart from live animals, the usual edible commodities derived from animals that are traded are fresh meat, milk and eggs. Their safety in rural communities is far from assured. In poor communities, dead animals or commodities derived from them may be sold, posing a risk to human health. Most cases of human anthrax in developing countries can be traced to the butchering and consumption of animals that have died of anthrax, a practice that not only often results in human illness but also results in environmental contamination with anthrax spores because the carcasses are not disposed of in the recommended way. Roadside sales of meat and dead animals (e.g. animals that have been hunted), often observed in developing countries, may not only result in the sale of diseased meat but the meat may have spent a long time at high temperatures and have been exposed to flies and other sources of contamination. The trade in bushmeat at both local and international level is globally regarded as a major problem that must be addressed urgently as it threatens biodiversity, food security in communities that for centuries have exploited wildlife for food in a sustainable way, and animal and human health. Informal sales of animal commodities may result in transmission to people of zoonoses like anthrax, pig tapeworm (Taenia solium), trichinellosis, bovine tuberculosis, brucellosis, salmonellosis and Rift Valley fever (RVF). These can result not only from butchering animals that have died of disease, but also lack of meat inspection, lack of pasteurisation of milk, and inadequate cooking. Diseases like anthrax, classical and African swine fever and avian influenza may also be transmitted to scavenging animals, in particular pigs, cats and dogs, as well as wild species, by careless disposal of remains. Public education is the only practical way to address the problem, since many rural areas lack animal health officers, but veterinarians are ultimately responsible for ensuring that accurate information about how diseases are spread and acquired is available to extension officers and other workers in rural communities. Skins and hides are non-edible commodities that are also traded, and while generally regarded as safe, an exception has proven to be transmission of anthrax spores in hides; occasional cases of anthrax in humans have been recorded that were traced to skins used in the manufacture of drums.

In the formal sector, where commodities derived from farmed animals are eventually sold through retail outlets like butchers, dairies and supermarkets, the concept that there must be reassurance of safety of the product from ‘farm to fork’ or ‘stable to table’ is widely accepted. Animal health managers are responsible for the part of the value chain that extends from the farm to the abattoir, milk or egg collection point, i.e. the point at which they cease to be closely associated with the animal. Once the commodities enter the retail chain they usually become the responsibility of the municipal health authorities, although this may vary between countries. However, the chain is seen is an unbroken entity and to ensure this there are increasing requirements for traceability that would enable the final product to be traced back with certainty to the farm and even the animal of origin. Sometimes the entire value chain takes place on the farm, or meat products are sold directly from the abattoir and in these cases the veterinary authorities might need to oversee the entire process. Abattoirs have served as a source of disease through

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the sale of offal not designated for human consumption as well as meat and organs condemned for various reasons, and the improper disposal of waste from the slaughter process. Most countries have legislation regulating these practices, and the difficulty lies in ensuring that the legislation is implemented. Sale at abattoirs should be restricted to the sale of edible products from animals that have undergone ante- and post-mortal inspection. The products should be handled and packaged hygienically and records kept of the transactions in the form of receipt copies or other sales records.

International trade in livestock commodities

When livestock commodities are exported or imported, regulatory mechanisms come into play determined by the importing countries guided by international norms and standards. These are discussed in much more detail in modules on marketing and trade, but the situation is briefly summarised here.

Rules and structures

Animal production is regulated by national legislation, which varies according to the country. It may determine where and under what conditions animals may be kept and what may legally be fed to animals. Animal health legislation has an impact on production, as it provides for the registration and use of veterinary medicines, which is vital for international trade. Livestock and livestock commodity trade is subject to regulation at both national and international levels.

At the international level, the World Trade Organisation (WTO) provides member states, through the Sanitary and Phytosanitary (SPS) Agreement, guidelines for fair trade in animal and plant commodities. The World Animal Health Organisation or Office International des Épizooties (OIE) is the body designated by the WTO to develop guidelines and standards for trade in animals and animal commodities. These guidelines are available through the Terrestrial Animal Health Code (TAHC) and the Aquatic Animal Health Code available on the OIE website, www.oie.int. The food safety standards for products destined for human consumption are set by a joint committee of the World Health Organization (WHO) and the Food & Agriculture Organization of United Nations (FAO), the Codex Alimentarius Committee. Some countries or trading blocs, in spite of WTO and OIE membership, impose their own standards that are generally higher than those of the OIE and make access to their high value markets very difficult for developing countries, especially in regions like sub-Saharan Africa where many major transboundary animal diseases are endemic. Many countries tend to follow the EU standards. This has various reasons. Firstly the OIE standards differ for different diseases and therefore a number of chapters in the codes have to be consulted in order to export meat, whereas the EU standards are simpler to follow. Secondly, some veterinary authorities would not like to be seen as imposing a ‘lower’ standard. Thirdly, countries that export to the EU are virtually forced to apply similar standards as importing meat under less rigorous provisions could jeopardise their status. In addition to standards set by trading blocs and individual countries, international companies and alliances are increasingly

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http://www.oie.int/


setting private industry standards. This situation provides challenges to the official international standard-setting bodies, which need to harmonise their standards as far as possible with market requirements reflected in the private standards without compromising their role in facilitating trade for all their member countries.

There are initiatives among regional bodies in sub-Saharan Africa to support intra-regional trade and to find ways to overcome the differences in animal health status that exist between member countries. COMESA (Common Market for Eastern and Southern Africa) has 19 members in southern and eastern Africa, from Egypt to Swaziland; SADC consists of 15 member countries in southern Africa, several of which are also members of COMESA, and EAC (East African Community) is a community consisting of Uganda, Kenya and Tanzania, the first two of which are members of COMESA and the last of SADC. There is also a West African bloc, ECOWAS (Economic Community of West African States). COMESA, SADC and EAC are exploring the establishment of a tripartite body with a focus on trade policies that will permit free movement of agricultural products among member states subject to some form of certification.

At national level, livestock trade is regulated by laws covering the movement and transport of animals, the slaughter of animals, and all aspects of veterinary public health and food safety.

Animal welfare is increasingly becoming important for trade in animal commodities as well as live animals, particularly in the higher priced markets. At national level, guidelines for the welfare of animals may be provided through Welfare Codes as well as legislation. The OIE is actively involved in developing standards for animal welfare and has so far developed seven standards relating to terrestrial animals, six of which provide for aspects of trade and disease control (transport of animals by land, sea and air, slaughter of animals for human consumption, killing of animals for disease control purposes and control of stray dog populations). Animal welfare is the subject of a dedicated module.

Risk mitigation for livestock commodities

The OIE provides guidelines for risk assessment for import and export in Chapter 2.1 of the TAHC. This is discussed in more detail in modules covering tools for animal health management including risk assessment. The concept supports the requirement of the SPS Agreement that prohibition of the importation of agricultural commodities must be scientifically defensible. It can also be used in support of Article 4 of the SPS Agreement that provides for countries to achieve freedom from infection for commodities by different pathways (principle of equivalence). Risk assessment can be used to evaluate whether these pathways result in commodities posing only an acceptable level of risk.

Classification of commodities and products (i.e. commodities that have undergone further processing) derived from animals, ranked in the order of the level of risk they may pose for transmission of pathogens that threaten animal or human health:

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Live animals

Semen, ova, embryos

Fresh or frozen products (meat, raw milk, eggs, offal/carcass meal, manure, raw hides, hair and fibre, serum and tissues used for biological products)

Processed products (processed meat, milk and dairy products, rendered carcass meal, tanned hides)

Within these categories there are variations in the level of risk posed. For example, hides in general pose a lower level of risk than fresh meat. The simplest way to mitigate the risk posed by a commodity for a particular disease is to derive it from an area that is demonstrably free of that disease, and this is the criterion on which most of the OIE standards are based. However, it is recognized that countries with few resources may find it difficult if not impossible to create and maintain zones that are free of diseases that are endemic in the region. A particular problem facing the SADC countries in this respect is the fact that the most trade-sensitive disease, FMD, is endemic in African buffalo. Achieving separation between buffalo and cattle involves the use of game-proof fences, which are contrary to principles of biodiversity conservation and are not an option in the vast transfrontier conservation areas that have been established in the region. The problem experienced by livestock farmers in such areas is highlighted in a DVD entitled ‘Beauty and the Beef’.

Increasingly, in order to overcome the problem of trade embargoes on livestock products from developing countries owing to the endemic presence of serious transboundary diseases within their borders, attention is turning to commodity-based trade. It has been demonstrated that certain commodities are unable to sustain or transmit infection, even if they originated from an animal that was actually infected, owing to the properties of the pathogen itself or to its distribution in the animal. For example, deboned beef from which the lymph nodes have been removed is unable to transmit FMD, because the post slaughter conversion of muscle glycogen to lactic acid provides an unfavourable environment in which the FMD virus is unable to survive, and standards could be developed to ensure the safety of the commodity. Article 8.5.25 in the chapter on FMD in the TAHC (2011) provides standards for export of beef from vaccinated animals in an infected area that, if adopted by importing countries, would largely address this requirement. The tissues in which the prions that cause bovine spongiform encephalopathy (BSE) are likely to be present have been identified. Provided that these specified risk materials (SRMs) have been removed from slaughtered cattle, the meat is safe for consumption. The prions are also not present in milk. Various pork products subjected to a lengthy curing process have been found to be unable to harbour the ASF and classical swine fever (CSF) viruses in spite of their ability to persist in meat for long periods. There are many other commodities for which standards could be developed. Animal health managers need to be aware of this and to be able to evaluate, at least within broad limits, whether the level of risk posed by particular commodities that traders wish to

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http://www.youtube.com/watch?v=jKAffQG21AE&feature=youtu.be

http://www.youtube.com/watch?v=jKAffQG21AE&feature=youtu.be


import is acceptable, and also to provide science-based arguments for the safety of products destined for export. It is important to emphasise that commodity-based trade does not open the door to sourcing products from sick animals. Animals that do not pass the usual ante- and post-mortem inspection will not enter the food chain. It does, however, invalidate the argument that because animals incubating a disease but showing no signs might accidentally enter the food chain, animals cannot be sourced from an infected area, thus excluding large numbers of livestock producers in Africa from international and sometimes even regional markets. This viewpoint is strengthened by recent research that indicated that shedding of FMD virus prior to development of clinical signs may occur only briefly.

Both COMESA and SADC have adopted commodity-based trade in principle and are busy with various initiatives related to feasibility and cost-effectiveness, recognizing that it is likely to be the only approach that will permit free trade in livestock commodities among countries ranging from those whose animal disease status is unknown but likely to be poor to countries like Namibia that are able to meet the EU conditions for export to their markets. At the same time, countries that have invested considerable resources in establishing export zones are seeking equitable solutions for large numbers of poor livestock owners who are excluded from the export market because they are not within the export zones, and this is also likely to involve commodity-based trade. The concept is also likely to support trade in products derived from the sustainable exploitation of wildlife, which will be necessary in order to ensure that biodiversity conservation provides benefits for communities living in or adjacent to conservation areas (the DVD referred to above provides a good insight into the situation).

Animal identification and traceability

High value markets for livestock commodities have stringent requirements for animal identification and traceability, especially for cattle. Identifying their animals has obvious advantages for the producers. It enables good record-keeping to monitor production and it also increases the possibility of recovering stolen livestock. Identification and traceability support animal health management by enabling better follow-up during outbreaks as well as proper registration of animals during interventions such as vaccination campaigns and surveillance for diseases, and may be a national requirement. However, the demand for traceability throughout the marketing chain by trading partners in industrialised countries may require resources that are simply not available in poorer countries. It is usually the responsibility of the animal health authorities to decide which systems are appropriate to their situation (for example individual animal identification vs herd or batch identification) and whether a large investment in identification will be justified in terms of the expected financial gains through trade. Further information about animal identification and traceability is available in a module on that subject as well as in relevant chapters of the TAHC (2011).

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Sheep and cattle identified by ear tags

Certification

One of the most important issues for international trade is the provision of certification for animals and products destined for export. The OIE provides standards and guidelines for the importation of live animals, semen, ova and embryos, and some of their derivatives such as fresh and frozen meat, hides, and fibres. According to these guidelines the competent veterinary authority of a country is responsible for certification that the traded goods pose no more than an acceptable risk for the transmission of pathogens that are harmful to animal or human health. Guidelines for certification are provided in Chapters 5.1 and 5.1 and model certificates in Chapters 5.10-12 of the TAHC. The Codex Alimentarius provides food safety standards for a very large variety of processed products including products derived from animals, but these standards refer only to safety in terms of human pathogens. In assessing the risk to animal health posed by certain commodities, veterinarians need to use their own technical knowledge of the way important animal pathogens behave to decide whether those commodities are likely to harbour them or not.

In order to provide credible certification of the health status of the animals and of the area from which they originated, countries must have surveillance plans and systems in place that provide assurance that as much information as possible about the health status of the country is available to the veterinary authority. The surveillance system should be backed up by a reliable laboratory diagnostic service. The OIE Terrestrial Manual for Diagnostic Tests and Vaccines available online at the OIE website provides an overview of laboratory tests for all the important animal diseases. Increasingly there is insistence that laboratories should provide quality assurance through a quality management system that complies with the international standard for analytic and testing laboratories, ISO/IEC 17025, developed by the International Standards Organisation (ISO) based in Geneva. There is also increasing pressure for laboratories to be accredited for compliance with this standard by an internationally recognised body.

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The act of processing livestock products often destroys any pathogens that may be present and renders the products safe. Thus, the heat process used in canning meat will inactivate most pathogens, excluding prions. Some but not all methods of curing pork inactivate the viruses that cause ASF and CSF. However, the actual safety of such products depends upon the processing having been carried out correctly. Thus, carcass meal rendered at the temperatures and duration required to destroy the BSE agent is safe regardless of whether it inadvertently contains SRMs from an infected animal, but this will only hold true if the processing was entirely reliable as certified. Process certification may not be within the scope of the competent veterinary authority owing to lack of specialised knowledge. This is a problem that will need to be addressed for the unreserved adoption of commodity-based trade. Certification is the subject of a dedicated module.

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CONTROL OF ANIMAL DISEASES TO SUPPORT ANIMAL PRODUCTION AND TRADE Animal disease control measures to support production and trade fall into two main categories: those measures required to deal with emergency situations created by the outbreak of a serious transboundary disease that was not previously present in the affected country or area, and those required to prevent diseases that are endemic from having deleterious effects on either livestock production or trade.

Control of endemic livestock diseases

Animal production in developing countries, particularly in Africa, is often severely constrained by the presence of animal diseases that cause high mortality, like peste des petits ruminants (PPR), ASF and Newcastle disease (ND), or result in poor performance, like the tick-borne diseases and trypanosomosis. The result may be a lack of animals to satisfy the country’s own needs as well as the lack of a surplus to export. Concerns are also raised about zoonotic diseases, which are more easily transmitted under conditions of close contact between humans and animals and where milk and meat are handled and consumed without being processed in any way that will destroy pathogens.

Vaccination of cattle against anthrax, South Africa (photograph courtesy of Anabela Manhiça, Mozambique Institute for Agricultural Research)

In sub-Saharan Africa, a number of serious transboundary diseases (FMD, RVF, PPR, CBPP, contagious caprine pleuropneumonia, bluetongue, sheep and goat pox, African horse sickness (AHS), ASF, ND, to name a few) are present endemically, usually in several countries. For some of these, particularly those in which maintenance of the agent occurs in wild animals, like FMD and ASF, eradication at least in the short term is not a realistic option. In order to trade in livestock commodities, these countries are required to adopt control measures that will convince trading partners that livestock commodities originating from

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these countries pose no more than an acceptable level of risk for transmission of endemically present transboundary diseases.

Routine disease control

Routine disease control activities are aimed at attaining or maintaining good animal health status and supporting animal production.

Routine disease control activities may include:

Programmes for control and/or eradication of specific diseases

Vaccination campaigns (procurement, storage, distribution)

Monitoring the results of disease control activities

Provision of treatment/clinical services by the state

Routine surveillance for diseases including changes in epidemiological patterns.

Control (managing the disease) and eradication (eliminating the disease) programmes require the participation of the livestock owners. Such programmes may be compulsory or voluntary, depending upon the nature of the disease and the available resources. Diseases that are frequently the target of sustained control programmes are erosive diseases that affect production and/or are zoonoses like brucellosis, bovine tuberculosis, rabies, tick-borne diseases and trypanosomosis, as well as transboundary diseases like FMD, contagious bovine pleuropneumonia (CBPP), and the swine fevers. Depending upon the disease, approaches include testing and slaughter of positive animals, vaccination, and vector control. All of these activities have cost implications, and in order to be successful must be well planned and implemented. Before embarking on a control programme, it is important to identify the target population and then to decide upon a strategy that will be both effective and achievable with the available resources. It will be necessary to determine what laboratory diagnostic capacity is available to support the programme if laboratory tests are involved. The wide spectrum of laboratory techniques described for each disease in the OIE Manual for Diagnostic Tests and Vaccines may not be available in the local laboratory!

Vaccination campaigns need careful planning and management. Most vaccines are fragile and require that the cold chain be maintained from manufacture to administration to the animal. Even so-called thermostable vaccines are usually thermotolerant but will not withstand prolonged storage at high temperatures. The procurement process for vaccines should ensure that they are delivered well in advance of their expiry date, in a way that will ensure maintenance of the cold chain. They should be stored in such a way that the recommended temperature (usually 2-8°C) is reliably maintained. Arrangements must be made to ensure that the vaccines can be kept cold

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throughout the distribution and administration process. Vaccines that have spent a hot day in an uninsulated container on the back of a vehicle in the sun are not likely to be effective and the whole effort will have been wasted. On the other hand, allowing liquid vaccines to freeze will usually render them ineffective.

Vaccination of dogs against rabies, Catuane, Mozambique

Whatever the nature of a control programme, monitoring its progress is extremely important and the monitoring strategy should be built into the programme from the beginning. Effective monitoring will permit identification of problems and enable changes of strategy to resolve them, and will also enable programmes that are clearly not working to be modified or abandoned. After control has been achieved, a surveillance programme should be maintained in order to intervene early at any sign of resurgence of the disease.

The provision of treatment and clinical services by government veterinarians when this is not linked to official control programmes is a matter for debate. In countries where no or very limited private veterinary services are available, or where a large proportion of the livestock producers are subsistence farmers who cannot afford private services, interventions by government veterinarians may be necessary. There is no doubt that the provision of primary animal health care enhances the image of state veterinarians and creates an opportunity to improve disease surveillance. Various attempts have been made to distinguish between “public” and “private” goods in the provision of veterinary services, the former involving animal diseases that are a threat to public health or the national economy, for example highly contagious diseases, while the latter refers to diseases that are in the farmer’s own interests to control. Greater private sector involvement has been advocated, but the practicality of this will of course depend upon the availability of private veterinary service providers as well as the ability and willingness of livestock

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producers to pay for the services. The provision of primary animal health care by trained community animal health workers (CAHWs) is an option that has proved beneficial when properly managed. Well trained CAHWs, who are members of the communities they serve, have proven invaluable in remote areas and among nomadic pastoralists who would otherwise have no access to veterinary services. They can also make significant contributions to surveillance for disease, as has been demonstrated in a study in northern Tanzania.

State-sponsored dipping programmes provide opportunities for surveillance and vaccination, South Africa

Options for managing endemic transboundary animal diseases to support trade in livestock commodities

As indicated above, the SPS Agreements of the World Trade Organisation are designed to prevent importing countries from unfairly using non-tariff trade barriers, e.g. risk of importing an unwanted animal disease, unless they can demonstrate that the risk posed by the imports is real and does not already exist within their borders. This means that they may not discriminate against countries that have an equivalent health status, but does not prevent them from prohibiting imports from countries that have a less satisfactory status in terms of serious livestock diseases. The requirement that an exporting country should have the same animal disease status as the importing country is widely accepted in industrialised countries. Since most of these are free from all of the serious transboundary animal diseases, it could theoretically be impossible for countries

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where one or more of those diseases occurs endemically to access the advantageous markets for livestock products afforded by the industrialised countries. In response to the need to provide market access for developing countries, the SPS Agreement recognizes the principle of equivalence, which permits export from countries that are not free of certain diseases provided that they can satisfactorily demonstrate that the commodities pose no more than an acceptable level of risk. In practical terms, this means that the commodities should originate from an area that is free of the specified disease/s, or should be demonstrably unable to transmit the specified infectious agent/s.

The OIE recognises geographical zones that are free for FMD, rinderpest (now globally eradicated), CBPP, AHS, PPR and CSF. Countries can also apply for a rating for the level of risk that they pose for BSE. In some SADC countries zonal freedom from FMD without vaccination has been achieved by using fences to effect physical separation between African buffalo and domestic livestock combined with buffer zones with vaccination and observation. The principle that a zone can be free of a specific disease with vaccination is accepted and is applied in Brazil, but to achieve freedom with vaccination it is necessary to be able to distinguish between vaccinated and unvaccinated animals. This is currently difficult for FMD within the SADC region, since the test used to distinguish between vaccinated and infected animals is regarded as insufficiently sensitive for the SAT virus types, but purification of the antigen used in vaccine production has greatly increased the sensitivity of the assay.

It has been accepted by the OIE that for certain diseases it will be virtually impossible to achieve geographically free zones, for example ND and avian influenza. A “new” concept, compartmentalisation, has been proposed, in which a production unit may be recognised as being free of a specific disease, allowing export of livestock commodities originating from that unit to take place. The concept is based on strict biosecurity of the unit, which applies also to the feed source, transportation of animals for slaughter, and the slaughter facility. Once a compartment has achieved official recognition by the competent veterinary authority (the OIE does not provide official recognition for compartments) of freedom from one disease, this status can obviously be extended to other diseases. It is recognised that the control measures that countries like Kenya and South Africa adopted for pig farms not long after ASF was identified as a disease entity in the first half of the last century effectively resulted in compartmentalisation of pig farms. The guidelines for zoning and compartmentalisation are defined together in the TAHC and there is a chapter on the application of compartmentalisation.

The commodity-based trade approach acknowledges that it may be difficult if not impossible for many developing countries with endemic transboundary diseases to achieve country or zonal freedom in the short term and that compartmentalisation will initially, at least, apply only to a few commercial producers able to achieve a high level of biosecurity in their production units. In spite of initial concerns that acceptance of commodity-based trade might reduce the impetus to eradicate transboundary diseases which is the stated aim of the OIE, it is increasingly accepted

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that if sub-Saharan Africa is to benefit from its livestock resources in ways that could change lives there has to be an alternative that will improve their access to global markets. Lack of competitiveness in terms of livestock numbers, quality and resources has been cited as likely to exclude sub-Saharan African countries from global livestock markets, but these impediments may be susceptible to change once trade in livestock commodities actually becomes possible because there are no longer definitive bans on particular areas.

Managing animal disease emergencies

Definition of an animal disease emergency

An animal disease emergency refers to any change in the status of a disease that can have potentially disastrous consequences in terms of animal health, human health, and/or the national economy.

Objectives of animal disease emergency management

Managing an animal disease emergency, which usually implies an outbreak of a highly contagious disease, is never easy, even with the best contingency plans in place and all the resources needed to implement them. Success can never be assured, because in the end the outcome depends not only on the actions of the veterinary department but also on the behaviour of producers and traders, which in spite of legislation may be impossible to monitor and control. It is therefore imperative to prevent disease emergencies as far as possible by ensuring good surveillance for animal diseases and identifying and managing risks, for example the management of airport and harbour swill.

If, in spite of all efforts to prevent it, an animal disease crisis occurs, the objectives of managing it include some or all of the following:

Limiting damage to livestock production when a disease emergency occurs

o Economic losses to livestock producers

o Economic losses in the satellite sectors – loss of trade, jobs

o Economic losses at national level – costs of importation to replace locally produced product, loss of export trade

Protecting public health

Protecting the environment

The Food & Agriculture Organization of the United Nations (FAO) has developed, under the EMPRES (Emergency Prevention System for Transboundary Animal and Plant Pests and

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Diseases) Programme (http://www.fao.org/ag/againfo/programmes/en/empres.html), a tool known as Good Emergency Management Practice (GEMP), available on CD and on the FAO/EMPRES website as a multi-media programme. It promotes the concept of a Code of Practice in dealing with animal disease emergencies.

GEMP in animal health is defined as follows: ‘the sum total of organised procedures, structures and resource management that lead to early detection of disease or infection in an animal population, prediction of the likely spread, prompt limitation, targeted control and elimination with subsequent re-establishment of verifiable freedom from infection in accordance with the International Animal Health Code’ [http://www.fao.org/AG/AGAInfo/programmes/en/empres/gemp.html]. The details of GEMP are covered in other modules.

Practical approach to resolving disease emergencies

Key issues that need to be explored when preparing a strategy for dealing with disease emergencies:

Identification of problem areas and risk factors (i.e. factors that place the success of disease emergency management measures at risk)

Identification and training of key personnel (include people outside animal health services)

Integration of stakeholders in disease emergency management

Awareness campaigns

Resources for animal disease emergency management

A variety of resources are required for managing animal disease emergencies:

Information

o Information about the disease

o Background information about livestock numbers and distribution and production systems

o Information from field services

o Information from laboratory services

Human resources

Financial resources

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Infrastructure, equipment, supplies

Appropriate contingency plans and Standard Operating Procedures (SOPS)

Failure to have one or more of these resources in place is likely to lead to failure to contain the disease emergency.

Information

The veterinary department should have access to up-to-date reference works on infectious and parasitic diseases, in order to understand the aetiology and epidemiology, as well as how to confirm the diagnosis. The OIE Manual for Diagnostic Tests and Vaccines, available on the OIE website (www.oie.int) provides basic information about each disease as well as details on the samples required for diagnosis. However, not all of the disease descriptions contain sufficient information about the epidemiology to be adequate for each disease as it occurs in different parts of the world. One way of ensuring ready access to information is to incorporate it in the contingency plan. When preparing the contingency plan (see GEMP and other modules on disease control), the introductory chapter should describe all the important aspects of the disease, and should be updated as necessary, using the most up-to-date reference works available.

A database giving the most up-to-date livestock figures available, with distribution maps and some information about production systems is invaluable for planning actions and identifying high risk areas.

Information from the field services in the affected area and also in unaffected areas is crucial for planning the response in both.

The contingency plan should contain the information about what diagnostic tests can be performed by the laboratory and what type of samples are required, but contact with the laboratory is essential to ensure that there are no obstacles to the performance of the diagnostic tests (for example lack of reagents, equipment not functional, or absence of crucial staff members), and if there are problems, what alternative arrangements have been made to overcome them.

Human resources

The contingency plan will have identified the human resources required for implementation. The emergency team, which will usually include members of the state veterinary service as well as the laboratory, is of vital importance in the first response to investigate the outbreak and initiate an epidemiological inquiry. Assistance may be required from other departments, for example extension officers, police and army officers, and the media. The necessary mechanisms to enlist

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http://www.oie.int/


their services should be in place to avoid bureaucratic delays. Their activities will need to be coordinated through a Joint Operations Committee or equivalent.

Lack of the necessary human resources is a serious constraint for control of disease emergencies. Often the veterinary services of developing countries are thinly spread. It is important that the contingency plan should specify who is responsible for what, and should also indicate who will substitute officials who are unavoidably not available when the emergency happens. Contact details for the emergency team members should be readily accessible, preferably at the front of the contingency plan, and updated as necessary.

It must also be recognised that a disease emergency takes priority over all other activities, and that undesirable as it may be, it offers animal health officers a unique opportunity to gain experience that should not be missed in favour of some routine activity that can be interrupted without serious consequences.

Financial resources

An emergency fund should be available for dealing with animal disease crises, from which the necessary funds can be released rapidly. Ensuring that such a fund exists is an important responsibility of the veterinary services, who should supply the technical inputs that will convince the decision-makers of the importance of rapidly accessible finance.

A mechanism for rapid release of such funds is vital. It is understandable that in government organisations measures for release of funds are often cumbersome in order to ensure that all the correct authorisations are in place. In the case of an emergency fund, arrangements must be in place to ensure that there is no question of waiting for an indispensable signature while the diseases sweeps unchecked across the country.

Infrastructure, equipment and supplies

The provision of infrastructure is with some exceptions not within the capability of the veterinary services, but it is important that the contingency plan should identify any shortcomings in this respect and propose ways in which they may be overcome.

Equipment includes vehicles and sampling equipment, including the means to keep the samples in a good state of preservation until they reach the laboratory. If stamping out of animals is to be part of the control plan or there are large numbers of dead animals to be disposed of safely, earth-moving equipment may be required. The contingency plan will specify the equipment needed.

Supplies will include protective clothing, disinfectants, and any other consumables (specimen jars, preservatives, swabs, etc.).

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Contingency plans and Standard Operating Procedures

These should be available and should be relevant to the situation in the country. They should also be tested, preferably by performing simulation exercises, and updated and modified as necessary. The GEMP guidelines of FAO/EMPRES include a concise summary of the nature and structure of contingency plans.

In addition to the resources mentioned above, the following are important resources:

Discipline and good practice at all levels in the livestock industry

Political will

Achieving these through dialogue and education must be part of the long-term strategy of the veterinary services, since, if they are not in place when an animal health crisis occurs, the consequences will inevitably be severe.

Conventional approaches to disease emergencies

The conventional approach to a disease emergency created by the outbreak of a highly contagious disease has traditionally been to eradicate it by stamping out, i.e. the compulsory slaughter of all infected and in-contact animals, sometimes of all the animals of the affected species within a defined area or radius. The slaughtered animals are destroyed by some process that prevents their consumption and dissemination, usually deep burial or burning or both. This is accompanied by quarantine of the affected area or areas, with strict movement control of animals and products out of the area. Disinfection of infected premises follows slaughter, and restocking is permitted after a prescribed period. In order to obtain their cooperation, livestock owners are usually compensated for the animals slaughtered. After discovery of a focus, the veterinary authorities attempt to trace back any movements into and out of the area that occurred before measures were applied, and to stamp out any other potential or actual foci that are detected in this way.

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Eradication by stamping out. Stamping out results in many carcasses for disposal by burning or burial

Until recently, this was the approach advocated by international organisations such as the OIE, the FAO and the EU. Increasingly, however, a combination of strengthening of public opinion against the mass killing of animals, the undoubtedly serious environmental implications of the disposal of vast numbers of carcasses, and the enormous expense involved are making it necessary to explore other options. A further reason to explore other options is the fact that expensive stamping out operations often fail to contain the outbreak and cause more damage to producers than the disease itself, particularly in developing countries.

Reasons why conventional control measures fail

In order to succeed, control measures such as quarantine, movement control and stamping out have to be applied immediately and rigorously, since the objective is to contain the agent within the designated area or cordon, and the escape of even one infected animal may foil that purpose. It is extremely difficult under any conditions, but particularly with limited resources, to apply measures sufficiently rigorously to ensure containment within the focus.

Factors that contribute to the failure of measures are the following:

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Failure of the early warning system, so that the “index” case is not the first case, and other foci of infection exist elsewhere undetected. Tracing back animal movements may result in the discovery of these foci or may fail to do so, depending on the level of cooperation of the population and also their level of information.

Tardiness of response, giving time for spread of the infection. Producers who know that drastic measures are going to be applied are likely to take advantage of any lapse of time to sell as many animals as possible.

Failure of movement control. When an outbreak of disease occurs, and in particular when the method of controlling it is compulsory slaughter, the incentive for owners to move animals to avoid the control measures is usually stronger than the ability to prevent animal movement. Road blocks, if efficiently operated, will prevent at least overt movement of animals along the roads, but these do not offer the only way out of the infected area. Furthermore, there are reasons why road blocks cannot always operate efficiently. Firstly, the sheer volume of road traffic in most countries makes it impractical to thoroughly search every vehicle that passes. Much of the philosophy of outbreak control is based on the measures developed for rinderpest, which among domestic livestock primarily affects cattle. Cattle are large and visible, but the smaller species and parcels of meat are much easier to conceal. Secondly, in developing countries where officials are poorly paid, the incentive to allow animals to pass may be greater than the incentive to prevent them.

Road blocks are not always effective in preventing movement of animals and animal products

Inefficient disposal of carcasses of infected animals. Particularly if large numbers of animals are involved, disposing of carcasses can present serious problems. Incineration of carcasses is

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recommended but the costs are high if the process is to be effective. Deep burial, accompanied by treatment with quick lime, is the alternative. Either way, a suitable site for disposal must be selected, and the immediate focus of infection may not offer the necessary conditions. Moving carcasses is hazardous from the point of view of spreading infection. Furthermore, in poor communities the destruction of large amounts of edible meat is not easily accepted, and in many instances carcasses have been disinterred and consumed or even sold for consumption. Telling people who are in the habit of eating animals that die that eating the meat will endanger their health is unlikely to have any effect, particularly if it rapidly proves to be untrue.

Failure to compensate owners for compulsory slaughter of animals. Prompt payment of market-related compensation may provide the necessary incentive for cooperation, particularly if the disease is of such a nature that it is obvious that large numbers of animals are going to die anyway. However, developing countries are often unable to pay compensation at all, let alone at market-related rates. The application of stamping out without compensation or with inadequate compensation is most likely to result in spread of the disease, since it will encourage clandestine movement and sales that, for reasons given above, will be impossible to prevent. Even when adequate compensation is available, problems such as bureaucratic delays in payment will result in future non-compliance.

Factors that prevent resumption of productive farming as soon as possible. These include requirements for excessively long ‘empty’ periods before re-stocking, lack of suitable animals for re-stocking, lack of funds for re-stocking, and unrealistic requirements for resumption of farming activities, for example provision of new housing and infrastructures according to unachievable standards.

Careful consideration is therefore necessary before embarking on an eradication campaign based on stamping out the infection. This should be clearly reflected in the contingency plan. There are circumstances when it may be feasible, for example if the index case is genuinely the index case, the source of the infection is clear (for example, contact with wildlife), and the affected herd or flock is well isolated, with relatively few animals that need to be killed and plenty of space to dispose of the carcasses.

For countries with a significant export market for meat, and therefore a strong incentive to regain disease free status as soon as possible, stamping out may be the only option. However, even in this case, the probability of success must be weighed against that of failure, and a cost-benefit analysis should be undertaken to ensure that the expected revenues from import will offset the cost of the control operation, or that the losses of revenue due to failure to control the outbreak will exceed the cost of control.

If there is a probability that the considerable resources invested in eradicating the outbreak will be wasted because they will fail, alternative control strategies should be considered.

One option is to limit the number of animals that have to be slaughtered by some form of emergency vaccination to contain the disease, usually by ring vaccination around the affected focus. In order to

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regain disease free status, it has been recommended that the animals that were vaccinated should be slaughtered to eliminate them from the population, but the necessity for this is open to question. When stamping out is not an option, for example in the case of rare zoological collections that are not infected, selective vaccination may be permitted. Vaccination of the total population has also been used as an alternative to stamping out, for example in some HPAI-infected countries where it was deemed impossible to achieve the requisite level of stamping out in backyard flocks.

Alternative control strategies

For most diseases, an obvious alternative to eradication by stamping out is vaccination, usually limited to the area around the outbreak, but sometimes considerably wider. Although the costs involved in purchasing and administering the vaccine may be high, the advantage is that the animals, other than those that are infected and die of disease, are available for sale and consumption, and do not have to be disposed of in an expensive and environmentally unfriendly manner.

The decision to vaccinate depends upon the availability of sufficient quantities of an efficacious vaccine, the funds required to pay for it, and the importance of the export market on which vaccination may have a negative effect. Another factor that contributes is the perception that vaccination as a means of control is an admission of defeat, will result in large numbers of carriers of the disease, and ensure that the disease becomes endemic. The fact that vaccination has played a central role in the eradication of rinderpest is apparently overlooked. Insistence upon the importance of “disease freedom without vaccination”, in other words the demonstrable absence of infection, has induced in many countries a reluctance to vaccinate that does not take local conditions into account, including the need to keep a fragile economy dependent upon livestock production alive and even to ensure household food security.

The obvious disadvantage of vaccination as an outbreak control measure is the fact that antibodies take some time to develop and attain protective levels, usually about two weeks after the first vaccination. This means that all efforts to contain the infection inside the focus must be made during the critical period, and, as indicated above, this may be very difficult to achieve.

Concern about the effect of vaccination on exports will naturally depend on the importance of the export market. Reluctance to import vaccinated animals or their products stems from the fact that until recently it was not possible to distinguish between antibodies resulting from vaccination and those resulting from infection. The development of marker vaccines offers a way to overcome this problem in the future, but for most diseases marker vaccines are not yet available, and progress in this field is hampered by the negative attitude of highly developed countries to vaccination, even in the face of serious outbreaks. However, this may change as eradication by stamping out becomes less and less acceptable. A simulation study performed after the 1997/1998 outbreak of CSF in the Netherlands, which was brought under control by stamping out of affected and neighbouring unaffected herds, concluded that emergency vaccination would have been the best option, with the advantage of sparing healthy pigs.

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The perception that vaccination encourages a carrier state and merely serves to disguise circulating infection is unfortunate, and ignores the important contribution that vaccination has made to disease control and even to eradication. Certainly the use of vaccination implies that either the infection or the risk of infection is known or suspected to be present. The infection, or risk of it, does not result from the vaccine, since the overwhelming majority of vaccines are based on pathogens that have been rendered incapable of causing disease, and reversion to virulence is extremely unusual, although it has been recorded in rare instances. Animals protected by vaccine, when exposed to natural infection, are usually unable to shed infective amounts of the pathogen and thus do not infect other animals, unless vaccination has not been effective or a breakdown of immunity occurs for some reason. Effective vaccination permits normal production to continue in the presence of infection and, in spite of misgivings on the part of trading partners, the derivatives of such animals pose little realistic risk for transmission of disease. In populations in which a high level of immunity is maintained by vaccination, and in the absence of reservoirs of infection in wildlife or vectors, the disappearance of the pathogen, resulting in eradication of infection, is a real possibility. In the case of diseases for which reservoirs exist in wildlife populations, the risk of infection will always be endemic, but with proper protection of domestic livestock, including by effective vaccination, there is no reason why the disease itself should become endemic in domestic animals. There are, however, requirements for successful vaccination, such as the suitability of vaccines (able to protect against the agent causing the outbreak), quality of vaccines, and a delivery system that ensures that the majority of the target population of animals will be effectively vaccinated; this usually includes respect for the cold chain. Vaccination as a disease control tool is dealt with in greater detail in a dedicated module.

The decision to vaccinate as an emergency control measure therefore depends not only upon cost and feasibility, but also on whether eradication of the infection without vaccination is a realistic and feasible option.

Sometimes vaccination may not be possible, either due to costs, or, in the case of some diseases, e.g. ASF, the lack of a vaccine. In these cases, given that large-scale eradication by stamping out is also not feasible, alternative measures must be considered.

In principle, the aim of emergency control measures is to reduce the size of the susceptible population as rapidly as possible. Both stamping out and various vaccination strategies have precisely this aim. Other ways to reduce the susceptible population include the supervised sale for slaughter of healthy animals through official outlets as rapidly as possible, and the protection of unaffected herds by the institution of biosecurity measures that will prevent contact with the pathogen.

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Permanent isolation of pigs in accredited farm, African swine fever control area, Limpopo province, South Africa

With pathogens that require direct contact for transmission, such as ASF virus, which will be used as an example here, protection of animals through simple but strict biosecurity measures that require the full cooperation of the owner will effectively remove such animals from the susceptible population. These measures when applied to ASF consist of maintaining the pigs confined, strictly limiting access to the herd, disinfection of clothing, footwear, and hands for people who have to have contact with the pigs, not feeding swill unless it has been boiled for at least 30 minutes, and avoiding any other practices that might result in infection. These include sharing boars, equipment, feed sacks, and anything else that could possibly be contaminated. If the owners of affected herds are agreeable, slaughter of the remaining in-contact animals should be undertaken. Compensation in the form of nucleus breeding stock is more economical than monetary compensation, and is usually acceptable to owners. The sale of carcasses or meat from infected herds is not acceptable, but owners can be permitted to use some of the meat for own consumption provided that it is thoroughly cooked. Under some circumstances, pigs that have apparently survived the outbreak may be allowed to live, although not to leave the farm, since animals that recover fully from ASF apparently do not become long-term carriers. Such pigs might remain infective for up to a month after recovery, and they should remain on the farm and not be slaughtered or their meat disseminated for at least three months to ensure that they do not infect other pigs.

The same principles apply to other diseases that rely on direct transmission or where airborne transmission is possible only over short distances. If a long-term carrier state is known or suspected to exist, as is the case for many bacterial diseases (e.g. bovine, tuberculosis, bovine brucellosis, glanders)

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animals known to have been exposed to infection that survive the outbreak should be slaughtered, or at least separated and subjected to testing and slaughtered if infection is confirmed.

Creating awareness during an animal health crisis

Livestock producers need to be informed as quickly as possible when their animals are at risk owing to an outbreak of a highly contagious disease. The most effective way to reach as many people as quickly as possible is via the public media (radio, television, newspapers). In this way the public will also be informed so that they will understand measures such as road blocks that may in some way affect them. This should be followed up by the dissemination to producers and other stakeholders in the industry of more detailed information on how to protect animals and on the measures that are to be applied. For this purpose the help of the agricultural extension services can be enlisted. Commercial farmers may be able to be contacted through producer organisations; the existence of farmer organisations at all levels is extremely helpful for disease control support.

The message should be clear, simple and easily understood, and not unnecessarily alarmist. It must also be technically correct and truthful. As indicated above with regard to the safety of meat from dead animals for human consumption, at least some of the producers will have sufficient knowledge to recognize untruths, and the entire message will then lose all credibility.

Pig farmers receive a pamphlet with photographs to assist in recognising African swine fever and a poster with simple instructions as to how to prevent it (Ivory Coast)

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Raising awareness about highly contagious diseases of animals should not only happen in response to an emergency. Awareness about diseases is essential for good surveillance, and, if an emergency occurs, it makes the public awareness campaign much easier, because there is a foundation of knowledge on which to build. Theoretically, at least, if sufficient awareness has been created, animal disease emergencies should be very rare events indeed.

Recovering from an animal disease emergency

The actions required in recovering from an animal disease emergency are the following:

Re-stocking after extensive losses due to mortality and/or control measures. The Terrestrial Animal Health Code of the OIE proposes “infective periods” for diseases during which re-stocking should not be undertaken, usually based on double the maximum incubation period of the disease. In practice, re-stocking should not commence until it is fairly clear that the outbreak is over in that particular area. However, the imposition of unrealistically long bans on re-stocking is unacceptable and can lead to the collapse of the sector, since people have to make a living and are likely to turn to other activities if they cannot resume farming within a reasonable period. The use of sentinel animals at no more than 10% of the normal stocking rate may be recommended to avoid serious losses if an error of judgement has been made and infection is present. Sentinel animals should be fully susceptible, and should be observed for a period that exceeds the incubation period of the disease. If at the end of that period the animals have neither developed clinical signs nor antibodies, the premises can be regarded as safe. The selection of sources of animals for re-stocking should be careful, particularly in developing countries where donors may offer animals. The animals should be from a source that is guaranteed to be free of unwanted diseases, and should be of a breed and type suitable for the farming system. The replacement of indigenous breeds with high quality exotic breeds with nutritional and management requirements that are far beyond the means of the recipient to provide will not be helpful and will compound the losses suffered during the outbreak. Such animals are also prone to disasters such as death as a result of eating toxic plants through lack of previous experience of them.

Risk mitigation: it is important to try to identify the cause/s of the outbreak in order to prevent recurrence due to the same cause. If the actual cause can be pin-pointed and eliminated, that is certainly the first prize. Very often it is not possible to determine with precision the exact cause of the outbreak, and very often as well the apparent cause is not the real cause, which will then be overlooked. It is therefore helpful to examine the circumstances under which the outbreak occurred and to decide whether they can be improved to reduce the probability of further outbreaks. This will probably involve intensifying awareness on the part of producers and stakeholders so that, even if they are not able to alter the system within which they operate, they are able to eliminate high risk factors, for example by boiling swill, reducing contact with wildlife, or improving biosecurity in general.

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Building on lessons learned: this is an ongoing process that involves working with stakeholders to achieve better prevention and control, and identifying and rectifying weaknesses in the system (for example by improving surveillance, exerting better control over the fate of waste from ports of entry and abattoirs, intensifying communication with stakeholders, repairing fences, or revising vaccination programmes).

FAQS1. What is the difference between a livestock commodity and a livestock product?

A commodity refers to a derivative of an animal that has not undergone further processing. For example, fresh or frozen meat is a commodity, corned beef, cured hams and canned meats are products; raw milk and eggs are commodities, once they have been pasteurised or otherwise heat treated they are products; raw hides are commodities, leather is a product.

2. What are the main impacts of animal diseases on trade?

The two most important impacts that animal diseases can have on trade are firstly lowered production or raised mortality that reduces quantity and quality of livestock and livestock derivatives available for trade, and secondly trade bans imposed by potential trading partners to prevent the introduction of diseases via livestock and livestock commodities.

3. Are there standards and guidelines for trade in livestock and livestock products, and if so, who decides on them?

There are standards and guidelines for international trade. The World Organisation for Animal Health (OIE) is mandated by the World Trade Organization (WTO) to develop and publish standards for trade in live animals and in commodities derived from live animals. The Codex Alimentarius, a joint committee of the World Health Organization and the Food & Agriculture Organization of United Nations, is mandated by WTO to develop standards for food safety; these apply to commodities and products that are destined for human consumption. Standards for trade within countries are usually provided for in national legislation.

4. Can the OIE force countries to implement their standards?

The OIE cannot enforce standards as it has no legislative powers; countries use the standards (or their own standards, which may be more or less exacting than the OIE standards) to determine their requirements for veterinary certification of livestock and livestock commodities entering their countries.

5. Who is responsible for managing animal diseases for trade, the government or the livestock producers, or both?

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Managing animal diseases is really a joint responsibility. The state normally takes responsibility for the management of serious transboundary animal diseases that can threaten other countries or that must be prevented from being introduced, as well as diseases that pose a very serious threat to human health. Producers are in general responsible for managing endemic diseases whose main effect is on production and productivity. In developing countries the lines are often blurred because the majority of livestock producers are smallholder and subsistence farmers who do not have the resources to manage the health of their animals adequately.

6. What are the most important diseases in southern Africa that have to be managed for trade?

The diseases endemic in the region that have the greatest potential to affect export are foot and mouth disease, African swine fever, African horse sickness and highly pathogenic avian influenza in ostriches; outbreaks of Rift Valley fever, especially in South Africa, also had negative effects on trade. A range of infectious diseases in the region can affect productivity, including the tick-borne diseases, trypanosomosis, blueongue, anthrax, bovine brucellosis, bovine tuberculosis, lumpy skin disease, contagious bovine pleuropneumonia, Newcastle disease and peste des petits ruminants, to name only the more important ones; some of these, in particular Rift Valley fever, anthrax, brucellosis and tuberculosis, can also affect human health.

7. Why is foot and mouth disease such a major problem for international trade when it is neither highly fatal to cattle nor a zoonosis?

FMD was eradicated at great expense from Europe and other parts of the developed world, where it caused considerable production losses. In high producing dairy herds in cool damp climates, for example, it is a much more severe disease than in cattle kept extensively in warm dry areas. It can also be a very severe disease in intensively kept pigs. In the recent SAT2 outbreak in Egypt there has been high calf mortality, presumably owing to the replication of the virus in the heart muscle, which rarely occurs in sub-Saharan Africa. This explains the reluctance of countries that have eradicated FMD to run the risk of re-introducing the virus.

8. If deboned, de-glanded beef is accepted as being a safe commodity because it is unable to transmit FMD, what else, if anything, would be needed to enable poor farmers in infected areas to export their beef to high value markets?

Apart from export-rated abattoirs to slaughter the cattle and prepare the meat according to international standards, the quality and quantity of cattle would need to be appropriate for the market. The infected areas are generally characterised by low productivity and poor quality of cattle, and this would need to change if a market that required a sustainable supply of high quality meat became available.

9. Which other diseases are of concern when it comes to exporting meat?

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Theoretically the main diseases of concern are those whose agents can survive for long periods of time in the carcass after the animal has been slaughtered, e.g. the swine fevers, but in practice any disease in food animals tends to have a negative effect on trade, even diseases like contagious bovine pleuropneumonia that are not transmitted in meat.

10. Are the fears of introducing animal diseases through meat realistic?

There are certainly many well documented cases of diseases like foot and mouth disease and the swine fevers in particular being introduced into countries via infected meat. What usually happens is that infected meat is fed to pigs as swill or is improperly disposed of and becomes available to scavengers. Recent disease events where the source of infection has been fairly convincingly established have pointed to galley waste from ships rather than legally imported meat as the problem. The risk from legally imported meat for human consumption is relatively low.

11. Is quarantine an effective way of ensuring that diseases are not introduced with live animals

That depends on the quarantine protocol and the quarantine facility, as well as the diseases themselves. Provided that the quarantine protocol ensures that the animals are able to be isolated for long enough for any disease of concern that they are incubating to manifest before they are released and the quarantine facility is secure and well managed and does not permit contact between different batches of animals, prevention should be effective. However, there are some diseases that are difficult to test for or that have very long incubation periods that might be able to remain unnoticed and only manifest later when the animals have been released. Examples of such diseases are glanders in horses and contagious bovine pleuropneumonia.

12. What is an animal disease emergency?

Animal disease emergencies usually involve diseases with high morbidity and high mortality in animals but can sometimes involve diseases where relatively few animals may be affected but there is a high case fatality rate in humans (rabies). They can result from the introduction of an exotic disease to a country, e.g. when classical swine fever was introduced into South Africa in 2005 it caused a disease emergency, or from the spread of a disease from an area where it is endemic to an uninfected area, e.g. the outbreaks of foot and mouth disease in Kwazulu-Natal in South Africa that emerged in 2011 and in previously free zones in Botswana in 2010, or from the sudden occurrence or increased incidence of a disease due to particular conditions, like Rift Valley fever, e.g. in East Africa in 2006 – 2007 and in southern Africa in 2010 – 2011.

13. When there is a disease emergency in food animals, does all trade in the meat of that type of animal stop?

Some countries will immediately place a ban on all the meat from the species of animals affected by the outbreak, but there are mechanisms that will allow trade to continue from areas or facilities

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that pose a negligible risk for transmission of the disease. For example, outbreaks of FMD in infected areas in countries with free zones from which meat is exported do not (or should not) affect trade from the free zones. Compartments that are recognised by the veterinary authority and trading partners as being free of particular diseases are (or should be) able to continue to trade regardless of the status of those diseases elsewhere in the country. For some diseases (Newcastle disease, avian influenza and, most recently, foot and mouth disease) trade can continue as long as there has been no outbreak during a specified period of time within a 10 km radius of the facility where the animals were raised/kept and the facility where the meat was processed.

14. What does surveillance for animal diseases involve?

Surveillance for animal diseases means having a system in place that will allow early signs of a disease outbreak or a significant increase in the incidence of a disease to be identified. The system requires the involvement of everyone involved in animal production and health because the veterinary authorities cannot be everywhere all the time and they need the support of the animal breeders and everyone else involved in the value chain. The topic of surveillance for animal diseases is covered in detail in a dedicated module.

15. Why is stamping out still used as a disease control measure when it causes so much disruption?

Stamping out is often seen as the only way to ensure that an outbreak is eradicated as quickly as possible, since the alternatives leave animals that might spread the disease alive. Countries or zones that are recognised as free of a disease but experience an outbreak can regain free status more rapidly if they opt for eradication by stamping out. For diseases for which no vaccine exists, there is a perception that stamping out is the only alternative. The main reason why stamping out is still undertaken is therefore to allow countries to resume trade as quickly as possible.

16. What are marker vaccines?

Marker vaccines are vaccines that enable vaccinated animals to be distinguished from naturally infected animals because by testing the animals it is possible to differentiate between the antibodies resulting from vaccination and those resulting from infection.

17. What role can the media play in influencing the effect of disease on trade in animal products?

The media can play a positive or negative role. When there is an outbreak of animal (or human) disease the public needs to know about it, particularly if they are likely to be inconvenienced by measures such as road blocks, or need to have their companion animals vaccinated, or certain products are going to disappear from the shelves of their butchery or supermarket. However, the media should be informed via press releases from the veterinary authority that provide the

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technically correct information about the disease and do not leave room for the media to capitalise on the possibility of raising panic. The novel H1N1 pandemic influenza in 2009 was a sad example of the negative effect that the media can have. In spite of repeated requests from WHO, OIE and pig industries worldwide not to refer it as ‘swine ‘flu’ this was ignored by the media and the result was huge losses to pig industries in spite of the fact that people, not pigs, transmitted the disease. The USA alone lost $1.2 billion in revenue from pork exports when 29 countries banned their pork at the start of the outbreak.

REFERENCES1. Allport, R., Mosha, R., Bahari, M., Swai, E. and Catley, A. 2005. The use of community-based

animal health workers to strengthen disease surveillance systems in Tanzania. Revue scientifique et technique, Office International des Épizooties, 24: 921 – 932.

2. Allsopp, B.A., Babiuk, L.A. & Babiuk, S.L. 2004. Vaccination: an approach to the control of infectious diseases. In Coetzer, J.A.W. & Tustin, R.C. (ed) Infectious Diseases of Livestock,(2nd edn), Vol.2 Cape Town, Oxford University Press: 239-247.

3. Anon 2011. Manual of diagnostic tests and vaccines for terrestrial animals. www.oie.int

4. Anon, 2011. Terrestrial Animal Health Code. www.oie.int

Chapter 2.1 Import risk analysis

Chapter 3.1 Veterinary services

Chapter 3.2 Evaluation of veterinary services

Chapter 3.3 Communication

Chapter 4.1 General principles on identification and traceability of live animals

Chapter 4.2 Design and implementation of identification systems to achieve animal traceability

Chapter 4.3 Zoning and compartmentalisation

Chapter 4.4 Application of compartmentalisation

Chapter 5.1 General obligations related to certification

Chapter 5.2 Certification procedures

Chapter 5.3 OIE procedures relevant to the Agreement on the Application of Sanitary and Phytosanitary Measures of the World Trade Organization

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http://www.oie.int/

http://www.oie.int/


Chapter 6.1 The role of veterinary services in food safety

Chapter 6.2 Control of biological hazards of animal health and public health importance through ante- and post mortem meat inspection

Chapter 6.9 Responsible and prudent use of antimicrobial agents in veterinary medicine

Chapter 8.5 Foot and mouth disease

5. Bradley, B. & Verwoerd, D.W. Bovine spongiform encephalopathy. In Coetzer, J.A.W. & Tustin, R.C. (ed) Infectious Diseases of Livestock,(2nd edn), Vol.2 Cape Town, Oxford University Press: 1408-1421.

6. Brückner, G.K. 2011a. Managing the risks of disease transmission through trade: a commodity-based approach? Revue scientifique et technique, Office International des Épizooties, 30: 289 – 296.

7. Brückner, G.K. 2011b. Ensuring safe international trade: how are the roles and responsibilities evolving and what will the situation be in ten years’ time? Revue scientifique et technique, Office International des Épizooties, 30: 317 – 324.

8. Catley, A., Blakeway, S. and Leyland, T. 2002. Community-based animal health care. A practical guide to improving primary veterinary services. ITDG Publishing, London.Catley, A. & Leyland, T. 2001. Community participation and the delivery of veterinary services in Africa. Preventive Veterinary Medicine, 49: 95-113.

9. Charleston, B., Bankowski, B.M., Gubbins, S., Chase-Topping, M.E., Schley, D., Howey, R., Barnett, P.V., Gibson, D., Juleff, N.D. and Woolhouse, M.E.J. 2011. Relationship between clinical signs and transmission of an infectious disease and the implications for control. Science, 332: 726 – 729.

10. Honhold, N., Douglas, I., Geering, W., Shimshoni, A., Lubroth, J. 2011. Good emergency management practice: the essentials. A guide to preparing for animal health emergencies.

11. Kaeslin, E. 2011. FAO’s work on sustainable use of bushmeat: Engaging in international policy processes and finding practical solutions at local level. Proceedings of the International Symposium on ‘The relevance of community-based natural resource management (CBNRM) to the conservation and sustainable use of CITES-listed species in exporting countries’, Vienna, Austria, 18-20 May 2011: 37-40.

12. Mangen, M.-J.J., Jalvingh, A.W., Nielen, M., Mourits, M.C.M., Klinkenberg, D. & Dijkhuizen, A.A. 2001. Spatial and stochastic simulation to compare two emergency-vaccination strategies with a marker vaccine in the 1997/1998 Dutch Classical Swine Fever epidemic. Preventive Veterinary Medicine, 48: 177-200.

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13. Mebus, C.A., House, C., Ruiz Gonzalvo, F., Pineda, J., Tapiador, J., Pire, J.J., Bergada, J., Yedloutschnig, R.J., Sahu, S., Becerra, V. & Sanchez-Vzcaino, J.M. 1993. Survival of foot-and-mouth disease, African swine fever, and hog cholera viruses in Spanish Serrano cured hams and Iberian cured hams, shoulders and loins. Food Microbiology, 10: 133-143.

14. Mebus, C., Arias, M., Pineda, J.M., Tapiador, J., House, C. & Sanchez-Vizcaino, J.M. 1997. Survival of several pork viruses in different Spanish dry-cured meat products. Food Chemistry, 59: 555-559.

15. Owolodun, O.A., Yakubu, B., Antiabong, J.F., Ogedengbe, M.E., Luka, P.D., Audu, B., Ekong, P.S. & Shamaki, D. 2010. Spatio-temporal dynamics of African swine fever outbreaks in Nigeria, 2002 – 2007. Transboundary and Emerging Diseases, 57:330-339.

16. Paton, D.J., Sinclair, M. & Rodrigues, R. 2010. Qualitative assessment of the risk for spread of foot-and-mouth disease associated with international trade in deboned beef. Transboundary and Emerging Diseases, 57: 115 – 134.

17. Penrith, M.-L., Thomson, G.R. & Bastos, A.D.S. 2004. African swine fever. In Coetzer, J.A.W. & Tustin, R.C. (ed) Infectious Diseases of Livestock,(2nd edn) Vol.2, Cape Town, Oxford University Press: 1088-1119.

18. Penrith, M.-L. & Thomson, G.R. 2004. Special factors affecting the control of livestock diseases in sub-Saharan Africa. In Coetzer, J.A.W. & Tustin, R.C. (ed) Infectious Diseases of Livestock,(2nd edn) Vol. 1, Cape Town, Oxford University Press: 171-177. Rich, K.M. & Perry, B.D. 2011. Whither commodity-based trade? Development Policy Review, 29: 331 – 357.

19. Rubira, R. 2007. Disease control options for emergency animal diseases – necessary yet sensitive elimination of disease. Veterinaria italiana, 43: 333 – 348.

20. Smith, K.M., Anthony, S.J., Switzer, W.M., Epstein, J.H., Seimon, T., Jia, H., Sanchez, M.D., Huynh, T.T., Galland, G.G., Shapiro, S.E., Sleeman, J.M., McAloose, D., Stuchin, M., Amato, G., Kolokotronis, S.-O., Lipkin, W.I., Karesh, W.B., Daszak, P. & Marano, N. 2012. Zoonotic viruses associated with illegally imported wildlife products. PLoS one, 7: e29505.

21. Taylor, N. & Rushton, J. 2011. A value chain approach to animal diseases risk management. Food Animal Production and Health Guidelines 4, Rome, Food & Agriculture Organization of the United Nations.

22. Thomson, G.R., Leyland, T.J. & Donaldson, A.I. 2009. De-boned beef – an example of a commodity for which specific standards could be developed to ensure an appropriate level of protection for international trade. Transboundary and Emerging Diseases, 56: 9-17.

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23. Thomson, G.R., Perry, B.D., Catley, A., Leyland, T.J., Penrith, M.-L., Donaldson, A.J. 2006. Certification for regional and international trade in livestock commodities: the need to balance credibility and enterprise. Veterinary Record, 159: 53-57.

24. Thomson, G.R., Tambi, E.N., Hargreaves, S.K., Leyland, T.J., Catley, A.P., van t’Klooster, G.G.M. & Penrith, M.-L. 2004. International trade in livestock and livestock products: the need for a commodity-based approach. Veterinary Record, 155, 429-433.

Websites

OIE www.oie.int

FAO www.fao.org

FAO EMPRES http://www.fao.org/ag/againfo/programmes/en/empres.html

FAO GEMP http://www.fao.org/AG/AGAInfo/programmes/en/empres/gemp.html

WTO www.wto.org

EU http://ec.europa.eu/trade/

COMESA www.comesa.int

SADC www.sadc.int

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http://www.sadc.int/

http://www.comesa.int/

http://ec.europa.eu/trade/

http://www.wto.org/

http://www.fao.org/

http://www.oie.int/

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