One of the significant asymmetries between farmers and pastoralists is that the capital of the latter is tied up in living animals which are subject to catastrophic declines through disease. An epizootic can eliminate an entire herd well before the veterinary services reach the area. Historically, this has had two consequences: pastoral herds never became very large, and herders developed elaborate systems of loans and animal exchange to reduce the risk caused by this type of disaster. It seems fairly clear that there were no effective remedies against major epizootics such as rinderpest, anthrax, contagious bovine pleuropneumonia (CBPP), etc. in the pre-modern era. The rinderpest epidemics that swept through Africa in the 1890s devastated pastoral herds throughout the continent and brought whole herding systems to an end. Major epizootics that could wipe out whole herds, and even debilitating diseases such as brucellosis, were virtually untreatable. The principal response to trypanosomiasis was simply to avoid vast swathes of the continent, while rinderpest could only be combated by taking the entire herd into a remote area.
A consequence of this has been that, after an initial period of suspicion, pastoralists have generally adopted modern veterinary medicine with enthusiasm. The result has been a major socio-economic transformation that essentially sabotages the notion of a "traditional" pastoralist. Vaccinations and drugs allow pastoralists to increase the size of their herds and to expand into regions that were previously closed to them (see Boutrais, 1986, 1995; Blench, 1994 for documentation of the movement of herds into subhumid regions of West Africa). By the 1930s, the Navaho had accumulated extremely large sheep herds because of the level of services available to them (Hoover, 1931). Fixed veterinary services have reduced pastoralists' flexibility to move their herds, placing greater stress on areas near where services are provided (Bovin and Manger, 1990). Unprecedented pressure was placed on feed and water resources, and stock that would have died in previous conditions was kept alive, creating large herds of poorly fed animals that often harboured subclinical pathogens.
A major problem has been that, when internationally organized campaigns against epizootics have ended, the normal veterinary infrastructure has been unable to supply a service of similar quality, and pastoralists have then become desperate for medicines. This usually stimulates the development of an extensive black market in drugs, many of which have expired and some of which are blatant fakes, and this can cause havoc with pastoral herds. Nonetheless, over recent years there have been considerable improvements in the techniques of reaching remote pastoral communities with veterinary services. The most important of these is the training of "paravets" who can treat minor ailments, recognize epizootic conditions and major traumas and alert the veterinary authorities. Such programmes are in operation in Ethiopia, Kenya, Somalia, Uganda, Chad, the Central African Republic and Mali, where they are achieving varying degrees of success (Catley and Walker, 1997). In addition, in some countries, traders and private vets are making drugs available in remote areas and treating animals; this has the advantage of providing some service where the government may provide none, but the obvious drawback is that there is no control over the quality and dosage of drugs. Pastoralists are increasingly taking control of the medication of their herds and are thus forced to make choices based on a very concrete appreciation of the economics of using drugs versus the value of an individual animal.
However, there is another, longer-term consideration. Just as the labour-intensive nature of traditional water points limited the use that could be made of them - and thus the potential for pasture degradation - so the limited effectiveness of traditional veterinary systems kept down herd size and, thus, pressure on resources. Veterinary programmes are usually initiated without any consideration being taken of their consequences for overall animal production (Konczacki, 1978). The medical aspect simply takes precedence, as it does in human medicine, and programmes are often self-perpetuating. When the impact on environmental resources is considered, there is usually also the hope that pastoralists will voluntarily destock, since their animals now have higher survival rates. The introduction of modern veterinary medicine demands a whole new management system, as the nature of a major threat - disease - is thereby radically changed (Bernus, 1983). Herd maximization is justified by the argument that, if there are more animals to begin with, the impact of shock events will not be so devastating. However, when resource availability becomes the single most important factor that limits herd size, this argument breaks down: the more the animals, the greater the shock.
Pastoralists are usually highly knowledgeable about the behaviour and physiology of their animals and, in many places, have developed traditional remedies for some complaints, especially chronic pathogens, before gaining access to modern veterinary medicine. This is not always the case; for example, among the Luri of the Islamic Republic of Iran there is marked disinterest in the health of animals and only a limited interest in modern remedies, reflecting an underlying low investment in the health of individual animals (Black-Michaud, 1986: 50). The study of this "ethnoveterinary" knowledge of animal health and indigenous remedies has now accumulated a considerable literature (see e.g. McCorkle, 1986; Mathias-Mundy and McCorkle, 1989).
Essentially there are two views about this type of ethnoveterinary practice: that it is of limited value and only useful when modern remedies are not available, and that it is a grossly underutilized resource that has been displaced as a result of the machinations of drug companies. Prior to the colonial era, the ability of livestock producers to deal with viral diseases and pathogens other than ticks or worms is believed to have been extremely limited. This view is somewhat controversial; an alternative is that ethnoveterinary techniques were widespread and more effective than they appear to be in hindsight. What is certainly true is that local remedies remain in use and pastoralists will continue to resort to them while the supply infrastructure and the cost of modern veterinary drugs remain out of reach. Failures in the delivery of veterinary services have a damaging effect on pastoralists' trust in the State and are often responsible for the diffusion of iatrogenic diseases, notably when animals gather for vaccinations that fail to arrive, thereby increasing transmission of the very pathogen that the exercise is intended to protect against.
Trypanosomiasis is a disease complex associated with the tsetse fly Glossina spp., found throughout much of sub-Saharan Africa and affecting wildlife, humans and livestock (Bourn et al., 2000). In humans it is the cause of sleeping sickness, which is usually fatal in the strain typical of eastern and southern Africa. Wildlife vectors include antelope species, bush pigs and monitor lizards which often acquire long-term symptomless infections. Livestock are susceptible at varying degrees, and may undergo progressive debilitation leading to death or may develop partial or near-complete immunity. Tsetse flies inhabit almost all environments in Africa, except the extremely arid, but their presence is highly dependent on animal vectors and, in many cases, gallery forest. The drastic environmental changes of the twentieth century continue to affect the numbers and distribution of tsetse; monitoring it is thus an ongoing and continuous exercise.
The attempt to eliminate tsetse, and thereby trypanosomiasis, has been a major feature of international and national livestock policy in Africa since the 1920s, with the first conference on the topic held in London as early as 1907. It has been, and continues to be, a major focus of donor investment through the International Scientific Committee for Trypanosomiasis Research and Control (ISCTRC) and various national bodies in East and West Africa. Yet there are two very different narratives of the history of research and action in the control of tsetse and trypanosomiasis. It is instructive to contrast these as a way of illustrating how international bodies make policy for pastoralists with only limited regard for empirical data and scant concern for the very people they are attempting to assist.
In the first version, trypanosomiasis is seen as being responsible for human sleeping sickness and lowered animal production. More important, it keeps livestock out of much of the continent, thereby decreasing access to a reliable source of protein and income generation and, consequently, affecting nutrition and maintaining poverty. If the tsetse fly can be eliminated - or trypanosomiasis defeated chemically - livestock production would become more productive in its traditional locales and would spread to those where it is currently absent (Ford, 1971). The major beneficial consequences would be improved protein supply and more effective farming through animal power. Hence the launching of major long-term programmes to eliminate tsetse through chemical spraying or the release of sterile males and to develop effective trypanocides. Although these have been reported as successful in a series of annual and project reports, they have never solved the problem. Indeed, in 1995, the Programme Against African Trypanosomiasis (PAAT) - the coordinating body for international agencies - noted that "despite all the efforts and expenditure devoted to research on and control of African trypanosomiasis, it is generally accepted that in general terms the impact of the disease is as great today as it was 40 years ago" (quoted in Bourn et al., 2000). The conclusion is not, however, that something may be defective in the analysis of the problem, but that efforts must be redoubled with even larger and more extensive projects.
In the second version, trypanosomiasis is just one of many diseases that affect African livestock, and the patterns of production across the continent reflect human adaptation to its incidence. In areas where game is abundant, tsetse is abundant and livestock correspondingly rare; humans can thus hunt to supplement their diets. Hence also, although some species of ruminant have been adapted to high-humidity conditions and are kept by forest-dwelling communities, these are never in significant numbers and are usually kept as a prestige enterprise rather than for economic purposes. When hunting eliminates animal vectors and arable expansion tsetse habitats, livestock move in, making up the protein deficit caused by wildlife elimination. Pastoralists are well aware of the threats that high-humidity environments pose to their stock, and have developed intricate cross-breeding strategies to limit mortality in their herds. Blench (1998b, 1999a) describes the cross-breeding strategies of the Fulše which allow them to move into the derived savannah cleared by cultivators on the northern edge of the forest in West Africa. In a somewhat poignant incident, a government project in Nigeria imported at considerable cost a large number of supposedly trypanotolerant ndama cattle from the Gambia by air and settled them on a ranch in the humid zone. However, mortality was substantially higher among the ndama cattle than it was among the animals of pastoral herders who had adapted their "non-trypanotolerant" cattle to local conditions and transformed their enterprise to meat sales.
Tsetse programmes have proceeded in Africa in spite of a surprising lack of knowledge about both biology and infrastructural capacity. Glossina spp. are too diverse and too co-adapted to the African environment to be defeated by simple warfare analogies. The claimed victories in tsetse eradication have almost certainly been due to anthropic effects, the hunting out of vectors and habitat conversion rather than to the strategy itself (Bourn et al., 2000). It is probable that the success of campaigns in the area of human health, for example those against smallpox and yaws, have unduly influenced those planning for tsetse eradication. However, the human diseases were susceptible to single-shot vaccinations and there was large-scale international infrastructural support. The troubling persistence of malaria would perhaps be a better parallel with tsetse; highly polymorphous and habitat-dependent, it requires the sort of sustained attention on the part of national governments that it inevitably does not receive.
This story has no moral except that, once established, different narratives tend to survive. These parallel interpretations of the situation will continue into the future, and they illustrate how pastoralists' actual strategies are inevitably ignored in the rhetoric of national and international agencies, irrespective of how often the term "participatory" is repeated. In some ways there are ironic parallels with the foot-and-mouth epizootics that affected Europe in 2001. In much of the world, foot-and-mouth is accepted as a continuing pathogen and its effects are minimized. Systems that exclude it completely make themselves vulnerable to a rapid and devastating spread, resulting in massive losses of stock and disruption of the rural economy.