Special factors affecting the control of livestock diseases in sub-Saharan Africa

M-L PENRITH AND G R THOMSON

Introduction

Although livestock production, particularly in the arid and semi-arid regions of sub-Saharan Africa, is of vital importance as a food source and for trade, it is also an integral part of social custom, tradition and wealth, and therefore of greater value than can be reckoned in mere financial terms. Furthermore, because epidemic diseases are more diverse and prevalent in these regions, animal production and household food security are more constrained by diseases than elsewhere,⁴ as many of the chapters in this book attest. The fact that many of the Office International des Epizooties (OIE) List A diseases (i.e. those considered most dangerous in terms of international trade) are indigenous to Africa, often makes it difficult for products that originate in Africa to gain acceptance to international markets where the best prices prevail.² A result is the perception—one hopes erroneous— that disease control is generally doomed to failure in most parts of the continent.

Successful control or eradication of livestock diseases requires a holistic approach that involves appropriate animal husbandry practices, careful surveillance and control measures such as zoosanitary provisions that are enforced, vaccination, chemoprophylaxis and chemotherapy. To be sustainable these actions must be cost-effective and practical, and be recognized by livestock owners as necessary and appropriate. Ideally, livestock owners and animal health authorities need to co-operate in endeavours aimed at more effective disease control. Unfortunately, in sub-Saharan Africa, this ideal is rarely achieved, which is arguably the major reason why animal disease control is generally less effective in this region than in most other parts of the world.

Another well-recognized constraint is finance, to which there are two aspects. In the first place, there is the question of the return on the investment in controlling animal health.

Studies in this area have generally shown that returns on such investment are highly positive (see The control of infectious diseases of livestock: Making appropriate decisions in different epidemiological and socioeconomic conditions),¹⁴ although there is a view that the cost of eradicating the 2001 foot-and-mouth disease (FMD) outbreak in the UK was greater than the benefit it achieved. The argument is that a cheaper, albeit more time-consuming, approach would have been more appropriate.¹⁵ The second aspect relates to who pays for control or eradication. In the modern world it is generally accepted that the ‘user’ — more accurately the ‘beneficiary’ — pays. This presents two problems because (1) in sub-Saharan Africa most communities dependent upon livestock are impoverished, and (2) when it comes to effective control or eradication of epidemic diseases, the beneficiary is not confined to livestock owners. It is generally accepted therefore that the State has this responsibility but, once again, many states in sub- Saharan Africa have rarely been able to afford large-scale control/eradication programmes. The eradication of contagious bovine pleuropneumonia (CBPP) from Ngamiland (north-west Botswana) in 1996/97 is a remarkable exception. When the disease appeared after an absence of more than 50 years ¹ the government of Botswana devoted more than US $ 350 million to that cause. At present, international donors make very significant contributions to the control/ eradication of epidemic animal diseases in sub-Saharan Africa but these are not sustainable in the long term. Nevertheless, donor-assisted programmes such as PARC (Pan-African Rinderpest Campaign) and its successor, PACE (Pan-African Programme for the Control of Epizootics), both of which were funded by the Food and Agriculture Organization, have made vital contributions to the eradication of rinderpest from large parts of Africa as well as to improved surveillance programmes.

In the event of epidemics, the measures and approaches necessary to control/eradicate them and prevent transboundary spread are generally prescribed by international convention based on experience and approaches accepted in the developed world, particularly western Europe and North America. In practice, it is often not possible to apply these measures effectively in sub-Saharan countries because of financial and/or logistical reasons. This sometimes leads to the accusation that the measures applied to control an outbreak were not properly implemented and hence the lack of success. However, it is often not recognized by donors and international agencies that the methods prescribed have no prospect of being successful in the environment in which they are applied.¹⁷ There is therefore a pressing need for control measures of epidemic diseases in sub-Saharan Africa to be more effectively researched in order to develop more practical strategies to overcome the special conditions that prevail.

Even in highly developed countries, the possibility that conventional control measures may not achieve the desired result without excessive financial losses has been demonstrated during the outbreaks of classical swine fever (hog cholera) in the Netherlands in 1996 and FMD in the UK in 2001. Failure to recognize disease early enough to prevent spread usually lies at the root of the problem. After the disease has been diagnosed, logistics, socio-economic factors and politics can all contribute to the failure of control/eradication measures wherever they are applied. However, the nature of the logistical, political and socio-economic problems differs between developed and developing countries.

Apart from the financial constraints discussed above, other factors contributing to the failure of control/eradication programmes include the lack of adequate or adequately trained and motivated human resources, the lack of infrastructure, discipline, political will, and, often, the lack of information. In addition to this, sub-Saharan Africa continues to be afflicted by civil strife, rendering effective animal disease control impossible in regions where insecurity exists. Even when peace prevails and the resources necessary for control can be supplied either by the government or by donor organizations, there are often cogent reasons why conventional control measures cannot work.

Control measures

Quarantine and movement control

In the management of contagious diseases, strict movement control must be enforceable for quarantine and other zoosanitary measures to be effective. In this context it is important to remember that movement control of livestock in most parts of sub-Saharan Africa – some countries in southern Africa being an exception – is difficult because the borders between most countries are ‘open’, i.e. there is usually no indication on the ground as to where the border is, and they are often not controlled. Members of the same ethnic group frequently live on either side of a border and people and livestock move freely from one side to the other.

Most important, however, is the requirement for pastoralists, who live in a wide belt across the continent, to move long distances, irrespective of country boundaries, in search of water and better grazing. Any attempt to stop historic transhuman practices is usually interpreted by pastoralists as an attempt to ensure their demise. In addition, even within countries there is often little differentiation between different land-use areas (e.g. wildlife and farming areas), and frequently livestock are managed on a communal basis rather than by individual farmers.

Where outbreaks of highly contagious diseases are diagnosed, their subsequent control/eradication ideally requires immediate deployment of people and resources to effect movement control so that the affected population is isolated from adjacent susceptible populations and transmission interrupted. Roadblocks are the most obvious means to this end. However, in most sub-Saharan countries our experience has been that roadblocks have been established very late in the course of the outbreak, if at all, and have not been effective in preventing movement of animals and livestock products. Bureaucratic delays and slow mobilization of the necessary funds are at the root of the problem. Although most countries have permanent police and/or army checkpoints along major roads, these fall under ministries unrelated to agriculture. The mechanism to allow them to act as veterinary checkpoints often does not exist, and complicated negotiations at ministerial level are necessary either to allow a veterinary presence at the points or to authorize the regular personnel to search for livestock and/or products. The establishment of a permanent inter-ministerial committee to respond to emergencies offers a possible solution. However, even if it is possible to establish veterinary checkpoints, they are seldom successful in preventing movement out of the infected area. There are several reasons for this. In Africa, movement of livestock is not restricted to roads, even if the movement is across international borders. Many people on foot and on bicycles will bypass any checkpoints placed on roads, particularly when moving illegal material. Much trans-boundary movement takes place in the same way, particularly in areas where the border, which may be a road or a river, cuts through settlements in which people are related to one another. Thorough searches of traffic passing through roadblocks are also impractical. Many roads carry heavy traffic, much of which consists of heavily laden public and long-distance cargo transport. The time required for adequate searches would bring traffic to a standstill for unacceptably long periods and would in fact encourage the use of minor routes. Furthermore, officials manning roadblocks are generally underpaid and poorly motivated, and may not confiscate animals or their products if offered inducements to ignore them.

The pressure to indulge in illegal movements can be very strong among poor livestock owners. Livestock often constitutes their only resource, and they have no reserves on which to fall back when the marketing of their animals is prevented. Entire communities are often affected, so that no money other than what can be obtained by selling animals or their products is available. Depending on the extent of the outbreak, this situation may be protracted. Furthermore, it is frequently beyond the power or volition of governments in sub Saharan Africa to insist on a complete cessation of trade for the duration of the outbreak, particularly if no compensation is possible. For example, when markets are closed by official decree, they are often replaced by unofficial markets that spring up in the vicinity.

It is arguable that the inability of most African countries to effectively control and trace animal movement when it becomes necessary to control outbreaks of contagious diseases such as CBPP, African swine fever (ASF) and FMD, is the major reason for their widespread occurrence in Africa. On the other hand, methods that have been applied in the developed world or even southern Africa are not practical in most regions of Africa. This is particularly so in the vast pastoralist areas of sub-Saharan Africa. Unless a solution to this conundrum can be found, effective control, much less eradication, of major trans-boundary diseases will remain a problem. Perhaps any real progress towards addressing the problem will necessitate frank acceptance of its nature as a first step.

Stamping out

In poor countries, and increasingly in developed ones too, the concept of ‘stamping out’ (i.e. compulsory slaughter and destruction of animals in the infected area) is accepted only with difficulty by livestock owners and the public at large. It is therefore doubtful whether this is a viable alternative in most situations. It has been applied successfully in Botswana to eradicate CBPP and also in Côte d’Ivoire and Ghana to eradicate ASF. In the latter two countries it is highly likely that the ASF problem will recur because both have largely uncontrolled borders and many countries in the region are infected.

The only way to ensure co-operation by owners, particularly if movement control is inadequate, is to pay marketrelated compensation for animals slaughtered. When state budgets do not permit such payment, or where payment is retarded, the entire operation is doomed to failure. Concerted efforts to avoid the forces of government are likely to succeed, and may result in even more rapid spread of disease than would otherwise be the case. When compulsory slaughter does take place, strict monitoring of the disposal of carcasses is necessary, and the carcasses should be rendered unusable.⁵ In poor countries, destruction of large amounts of edible meat is a very difficult concept, and exhumation of buried carcasses is common.

Vaccination and chemoprophylaxis

Prevention of both serious epidemic diseases and erosive diseases of livestock often depends on either vaccination or chemoprophylaxis, or both. This presupposes access to the necessary products and sufficient financial means, either on the part of government or the owners, to purchase them. In areas far from cities and towns, or, as is the case in many countries, in all regions other than the capital city, products are often simply not available.

This is further complicated when products, usually vaccines, require an unbroken cold chain in order to retain viability. Inability to read the instructions supplied in order to use the products correctly is also a problem in many areas in the region. Even when outlets for storage and sale of products are provided, either by the state or by the private sector, storage facilities and back-up advice and service may be less than optimal.⁷ In this respect, drugs — both conventional commercial products and traditional remedies—are sometimes more easily obtainable from unofficial traders than through veterinary or pharmaceutical agencies. This means that the authenticity and/or storage of the products supplied may be dubious, which can result in animal owners wasting their hardearned money on inappropriate or ineffective drugs. To some extent this problem is being countered by community- based animal health workers (see below) who have received some basic training in animal husbandry and health and who are employed by the animal owners in the communities in which they operate.^{3, 8} In many countries this approach is largely being advocated and financed by aid agencies, and it remains to be seen how viable the initiative will be in the long run.

In the event of an outbreak of disease, ring vaccination may be indicated to prevent spread. The expense of vaccination, like that of compensation, may prove too great for the government to bear. Even when donor funding and vaccine are available, lack of infrastructure, such as passable roads into the area, serviceable vehicles and the wherewithal to maintain teams in the field, may delay delivery of vaccine and result in the cold chain being broken. Maintaining sufficient trained personnel in the area to administer the vaccine also has cost implications that may not be feasible for the state to cover.

The complexities and interaction of some of the factors outlined above are illustrated by the problem that has arisen with respect to rinderpest eradication in eastern Africa. Since the early 1990s, ‘mild rinderpest’ has become prevalent in some parts of that region, particularly in the Somali eco-region that encompasses parts of Somalia, Kenya and Ethiopia. The viruses concerned have so far all been members of ‘lineage 2’.¹⁶ There is usually little if any evidence— other than residual antibody—for the presence of the infection in cattle while wildlife, chiefly African buffalo (Syncerus caffer), may have more obvious disease.¹¹ The result is uncertainty as to how to go about controlling the problem. Limited ring vaccination is not advocated because it is difficult to be sure of the exact limits of spread of inapparent disease. Mass vaccination over a wider area is also problematic because it becomes expensive and difficult to persuade livestock owners that such resources be devoted to a disease they do not recognize as serious. At present, there is no scientific evidence that mild strains of rinderpest virus are able to revert to the virulent form, although it is an obvious danger.

Surveillance and monitoring of diseases

Maintenance of adequate surveillance in order to detect occurrence or an increase in the prevalence of economically important animal diseases at an early stage is vital for effective disease control in any circumstances. However, to retain an effective country-wide surveillance system is expensive and the benefits are usually long-term and not always appreciated by those who control the treasury. Approaches to, and minimum standards for, surveillance are currently under consideration in many African countries and constitute a specialized field in its own right. There are a number of texts that deal with this subject that should be consulted for detailed information (see The control of infectious diseases of livestock: Making appropriate decisions in different epidemiological and socioeconomic conditions).^{18, 19}

When an outbreak has occurred, surveillance and monitoring both during and after the outbreak are essential to establish the extent of the outbreak, determine how effective control has been, and ascertain its origin. It is frequently necessary that resources in addition to those of the veterinary service of the country concerned are made available during and immediately after a serious outbreak of an epidemic disease. The major additional requirements are usually trained personnel, transport and equipment to mount an effective campaign. However, maintenance of surveillance activities beyond the outbreak to assist in preventing recurrence and to enable early detection is often extremely difficult. The fact that donor resources are usually available during outbreaks has engendered a perception that transboundary disease control is an international rather than a national responsibility. This has serious implications for sustainability of control programmes.

Alternative approaches to disease control/eradication

When considering approaches to disease control, it is important not to lose sight of the reasons for control, facile as this may sound. These may vary, but with the exception of a few countries in the region, the most important reason for control is to enable production to continue at a local level rather than to protect international trade. If livestock diseases can be adequately controlled at local level, commercial production has a chance to reach a level at which formal export becomes a reality. Control measures should therefore be designed primarily to protect the interests of the livestock owners and not to destroy their enterprises to the extent that they will be unable to resume them for a long time by, for example, wholesale stamping out. The most successful control measures will be those that are understood and applied by the livestock owners themselves, since they have the most to gain from successful control. For livestock owners to play either a leading or supporting role in disease control, they need to be informed about the diseases and trained in methods of preventing their occurrence. These methods may demand modification or even complete change of their husbandry system.

In sub-Saharan Africa livestock disease control measures are required for two completely different levels of production. Commercial livestock farming, which is undertaken entirely to generate profit, ranges from small- to large-scale, and includes dairy farming, feedlots, and intensive production of pigs and poultry. These enterprises have increased in number during the last decade. Explosive urban growth has necessitated higher levels of food production on less land, which favours commercial production.

By far the greater numbers of livestock are still produced in traditional systems, where animals range extensively and are given little or no supplementary feed. In the more arid parts of Africa, livestock keepers are often nomadic.

Disease control in commercial production systems
Disease control is more easily applied in commercial, more intensive production systems than in extensive systems. It is also crucial, because concentrations or confinement of animals particularly where large numbers of animals are involved, favour rapid spread of contagious pathogens. Additionally, high morbidity and mortality in commercial systems may prompt panic selling of animals through outlets that reach a wider market, and can contribute materially to the spread of the epidemic.

Commercial enterprises are more amenable to effective disease control/eradication for the following reasons:

• owners are often more educated and informed;
• owners are generally more willing to spend money on higher-producing animals;
• access to veterinary services and other resources is generally better;
• quarantine is much easier when animals are restricted to a defined area; and
• marketing of animals and products often takes place through formal outlets where some form of veterinary inspection is available.

Additional advantages are that the number of animals is usually known, or easy to count, and animals may be individually identified. Records of purchases, sales, births and deaths may also be kept. Owners will often seek veterinary assistance when animals are ill or unusual mortality occurs. This encourages rapid reporting of disease emergencies. Owner compliance with control measures to deal with disease emergencies depends strongly upon convincing them that the advantages of control/eradication of the disease outweigh the short-term advantage of evading the control/ eradication measures and selling as many infected animals as possible. The key factors in successful disease control/ eradication in the commercial sector are therefore:

• organization of the industry;
• awareness, information and training;
• a holistic approach to on-farm biosecurity to prevent outbreaks;
• ensuring that when outbreak control is necessary, damage resulting from control measures is limited by assurance of market-related compensation for compulsory slaughter and/or other measures that encourage owner compliance; and
• participation of owners in disease control surveillance and monitoring.

Disease control in traditional production systems

Disease control is challenging in traditional production systems as these enterprises do not have ready access to veterinary services. Although the animals themselves represent wealth, their owners frequently have little or no ready cash to spend on animal health care. Because production in these systems is low, large numbers of animals may be kept to offset higher mortality and lower reproduction rates, and the value of the herd is often measured in the number rather than the quality of the animals. If animals are sold, marketing is usually via informal outlets. While cattle owners, in particular, are often highly knowledgeable and skilled stockmen, their attitude to livestock diseases may be stoical rather than pro-active

The principles of disease control are identical whatever the production system. The challenge in traditional systems lies in how to practically apply control measures given the lack of resources, information and, sometimes, the very different outlook of subsistence livestock owners. Ultimately, however, the aim would be to promote transformation from traditional to commercial systems of production. Given that livestock owners depend upon their animals to provide them with the necessities of life, few of them would refuse the opportunity to improve the income or life support generated by keeping livestock. Historically, development has depended upon the commercialization of agriculture, and there is no doubt that, given the opportunity, sub-Saharan Africa can achieve the necessary level of disease control for optimal animal production. Being a latecomer to the developed world, it may even be possible for Africa to avoid some of the problems that are inherent in excessive intensification of animal production.

Community-based animal health care, although not a new concept, has been developed to address the need for access to veterinary services in rural, frequently pastoral, communities usually far removed from the official veterinary service of countries.³ It has been formally applied in several African countries for varying lengths of time and with varying degrees of success.^{3, 8, 12} Obviously, owners have practised a degree of primary animal health care ever since humans have domesticated animals, and there is no doubt that considerable knowledge exists among those who possess traditionally kept animals. However, the diagnosis of disease is often a problem, as is the availability of suitable remedies.^{7, 13, 20} Community-based animal health care systems are most successful when based upon existing knowledge and when there is an obvious gain for the community.^{3, 9} Because community-based animal health care increases awareness of and information about animal diseases, and concentrates upon prophylaxis, including vaccination for serious diseases, it can make a vital contribution to improving disease control, particularly in traditional systems of animal husbandry in remote areas where there are currently no other options. The contribution of community-based animal health care programmes to control livestock diseases depends largely upon the perceived importance to the community of those diseases, as well as the approach adopted. Rinderpest control via community animal health workers achieved considerable success in the Afar region of Ethiopia and in Sudan, because livestock owners had no doubts about the effect of the disease.³ On the other hand, tsetse fly-control programmes that were theoretically community based enjoyed varying degrees of success, which was at least partly ascribed to the fact that the priorities of the technologists and the communities did not coincide.³ Only when it was recognized that tsetse flycontrol provided tangible benefits were communities prepared to commit time and resources to maintaining and, where necessary, replacing targets.

Information and awareness are essential at all levels of livestock production for disease control. The livestock owner or herder is the first line of defence, as he/she is in daily contact with the animals.¹⁰ Two of the essential elements of disease control, namely early warning and surveillance, depend strongly upon disease recognition and reporting by owners or members of the community. In spite of the knowledge that exists among traditional livestock keepers, most are eager to improve on this knowledge and are highly receptive to information, provided it is delivered in a form that they can easily understand. The incorporation of high-quality photographic material showing signs and lesions familiar to them greatly enhances acceptance and learning. Ideally, the information should be transmitted to owners by the veterinary services of the country concerned, who can at the same time identify lines of communication for reporting diseases that require government intervention.

However, where this is not possible, the function may be taken over by private or nongovernmental organizations, who may also serve as the first link in the line of communication to the veterinary authorities. In a disease emergency, participation of livestock owners in formulating and implementing control activities is vital for the success of the exercise.⁶

Globalization is increasingly becoming an impetus for change in many spheres and livestock production is unlikely to prove an exception, even in the remotest parts of sub- Saharan Africa. Thus the present preoccupation of the developed world with diseases such as FMD, bovine spongiform encephalopathy and food safety generally will force any country wishing to export to developed countries or trade blocks to be able to certify their livestock and livestock products accordingly. An example of the difficulties that result has been provided by the events surrounding the apparent spread of Rift Valley fever (RVF) virus from the Horn of Africa to the Arabian Peninsula where, in 2000/1, several hundred people died of RVF in Yemen and Saudi Arabia. As a consequence, a ban was placed on the traditional annual export of millions of sheep and goats to the Arabian Peninsula — particularly at the time of the Haj — causing great hardship to the pastoralists of the Somali ecoregion who rely on this trade as their major source of income. The internationally accepted guidelines on the requirements for ensuring freedom from RVF contained in the OIE’s International Animal Health Code² require updating, particularly from the African perspective. Additionally, so far African countries have not managed to bring their collective resources to bear in addressing such problems. It is therefore vital that the African perspective is conveyed more successfully into international forums such as the OIE and the World Trade Organization, where trade-related decisions are made, to ensure that developing countries are not ‘victimized’, albeit unintentionally.

Change from traditional to commercial livestock production systems seems unrealistic, especially when one considers the nomadic livestock systems practised widely in arid parts of Africa. Nevertheless, there is no doubt that in some areas change has taken place, at least with respect to the marketing of cattle. Expanding cities have increased the demand for meat by people who cannot keep livestock themselves. Large numbers of cattle, sheep and goats from the Sahel find their way to coastal markets such as Abidjan, Cotonou and other coastal cities, indicating that their owners are willing to undertake commercial enterprises. Conditions under which livestock are kept and marketed are dictated largely by feasibility and by the advantages perceived by the owners. Given sufficient incentive through increasing market demand and the dwindling land available for migration, there is little reason to suppose that Africa would not respond, as other regions have, by adopting more sophisticated husbandry systems.

Initially, changes in production systems are most easily effected with the short-cycle species, in particular pigs and poultry. Currently, large numbers of scavenging pigs and chickens are an indispensable part of life in villages in many African countries. The survival of these animals is crucial to their owners, to whom they represent household food security and, in the case of pigs, a mobile bank to meet unexpected expenses. Scavenging systems require no input from the owners and serve additional useful purposes such as environmental cleaning, but production is generally very low and mortality unacceptably high from causes unrelated to disease, such as road accidents, predation, malnutrition, and eradication because of damaged crops. The productive potential of pigs is such that relatively small inputs can result in sizeable gains. Convincing owners to change from extensive to more intensive production systems should therefore be relatively easy, particularly if local ‘champions’ can be identified who, by precept and example, can convince other owners of the profitability of improved enterprises.

The inherent resistance of indigenous breeds of domestic livestock diseases endemic to the region should not be under-estimated as a means for disease control.¹² Much research is still needed in this field. However, upgrading production systems by the wholesale introduction of animals of exotic breeds that are not suited to African production systems and are highly susceptible to the diseases that are endemic in the region, is a recipe for disaster. Such animals can usually only be successful in artificial systems where complete protection from vectors and diseases, and an appropriate level of nutrition and management can be achieved. Retaining and improving the genetic resources that exist in the region is vital for improving production and control of livestock diseases in sub-Saharan Africa.

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