R. Allsopp
CURRENT CONTROL METHODS
1. The direct control of trypanosomiasis is well documented and methods have changed relatively little over the past 40 years (Murray et al 1991). Antigenic variation remains a major obstacle to the development of a much needed vaccine although efforts continue to outwit this intractable parasite. Berenil and samorin remain the stalwarts of chemotherapeutic control and there is no signs of replacements. Their use is usually subject to Government legislation but this is often abused by farmers who underdose to reduce costs. Drug resistance is epidemic and the probability of major problems in the future, as with malaria, cannot be ignored.
2. Trypanotolerant cattle remain an important option but they have not been widely used beyond the geographical boundaries within which breeds like the N'dama are endemic. (d'Iteren and Trail 1988; Murray and Trail 1983)
3. Tsetse control methods are also well established and thoroughly documented. Aerial and ground spraying, odour baited traps and targets (with or without insecticidal impregnation), the sterile insect technique, application of insecticides - by dipping or pour-on formulations - to cattle have been reviewed many times over the past few years (e.g. Alsop 1993; Allsopp, 1992; Hursey 1985; Mulder 1989; Wall and Langley 1991). Of these, ground spraying has probably cleared more areas from tsetse infestation than any other and aerial spraying has the proven capability to rapidly reduce tsetse densities over huge areas. Both have caused concern because they apply large volumes of insecticide directly into the environment. They have, however, been subjected to comprehensive monitoring and although neither was shown to have lasting non-target effects (Douthwaite 1992; Douthwaite and Tingle in press, SEMG 1993) their use has declined almost to non existence.
4. Odour bait techniques have been adopted enthusiastically by control authorities and donors on the strength of their flexibility, low unit cost, reduced usage of insecticide and suitability for local community management. As they proliferate and become more routine it is increasingly apparent that their dependence on access roads has environmental implications, the length of time needed to effect significant reductions in tsetse density increases the cost and eradication seems no more likely than with any other technique (Mohamed-Ahmed et al 1992, Cuisance et al 1992). Traps and targets can be damaged by fire, wind and wild animals although the most common operational problem appears to be theft. Involving the local community to reduce theft and particularly in a management role is generally more complex than anticipated (Laveissiere and Meda 1992; Locks 1993).
5. There are many reasons why control is not sustainable and it is seldom due to intrinsic limitations of the technique. Successfully cleared areas have often become reinfested through reduced national capability to fund large scale operations or maintain effective barriers. Without international financial support this would undoubtedly have been even worse.
6. Unfortunately this support is usually conditional. Declining national capability can be compounded by limitations imposed by donors responding to 'global environmental concern' and this is not necessarily rational or scientifically sound. Control authorities have, for instance, reduced their dependence on chemical control techniques using inexpensive chlorinated hydrocarbon insecticides. Rightly or wrongly, this has limited their control options and the most notable effect in recent years has been the shift from ground and aerial spraying to the use of traps and targets.
7. This has not resulted in major reductions in disease distribution. In spite of huge expenditure over many years on operational control, research and training, trypanosomiasis is not decreasing, nor is the distribution of tsetse (Rogers and Randolph 1986). There are areas where they continue to persist despite long term, continuous efforts to eliminate them (Kenya's Lambwe Valley, Botswana's Okavango Delta, Cameroun's Adamoua Highlands, the Busoga area of Uganda). Others where they continue to advance (Ivory Coast, Nigeria, Togo, Zambia) or where past successes are slowly but inexorably eroding. (Uganda, Zimbabwe, Cameroun, Botswana, probably Somalia). There are vast areas in Zaire, Angola, Tanzania and Mozambique where we have little or no idea about current distributions; only the certain knowledge that they prevent resettlement, constrain national agricultural production and continue to threaten that of their neighbours.
8. Tsetse and trypanosomiasis control methods are clearly not working as well as they should, research and training is not having the desired effect and donor support is perhaps, at best, of short term value. As human and livestock densities continue to rise, and both utilise areas of marginal agricultural value or higher epidemiological risk, the threat from tsetse and trypanosomiasis will inevitably increase.
9. We cannot expect any major new developments in the near future and the methods we have for tsetse control and chemotherapy, though far from perfect, will remain the first line of defence for the foreseeable future. Realistically, therefore, we must seek to improve the effectiveness and sustainability of these existing methods. This will involve better use of resources, for instance, by pooling regional manpower, facilities and international support. It will also require increased understanding of the problem, building on historical experience through greater interchange of information and more effective targeting of research and training.
10. Many of these points were noted by previous FAO Expert Panels and by the Commission on African Animal Trypanosomiasis which voice the collective concerns and aspirations of 35 nations directly affected by the disease. The recommendations of these two bodies provide guidelines within which efforts to improve efficiency and sustainability should be applied.
BRIEF REVIEW OF RECOMMENDATIONS OF THE COMMISSION, THE PANEL OF EXPERTS AND THE INTER-SECRETARIAT COORDINATING GROUP ON AFRICAN ANIMAL TRYPANOSOMIASIS AND RELATED DEVELOPMENT (1991)
11. Sustainability agricultural production and tsetse control were the underlying themes of these meetings. The role of FAO in coordinating activities to meet these objectives was stressed throughout.
12. The former theme was reflected in the title of the Panel of Experts meeting which addressed the problems of 'trypanosomiasis control as an element of sustainable agricultural production'. This acknowledged that trypanosomiasis is only one of many constraints to productivity, should not be viewed or treated in isolation and should be controlled within the context of land use planning.
13. Sustainability of trypanosomiasis control has obvious implications for national control authorities and for allaying donor fatigue. Strategies must be realistic, appropriate and not dependent upon open ended international support as reflected in references to institutional strengthening, community participation and cost recovery schemes.
14. The meetings reiterated many general points which still apply. For instance, the need to exploit trypanotolerant cattle; the continuing, widespread reliance on drugs to combat trypanosomiasis and thus the need for effective infrastructural support, field diagnostic techniques and reliable drug supplies. The importance of institutional links, information dissemination and training.
15. There was a shift in the attitude to environmental monitoring; accepting that the direct effects of insecticidal treatments had been throughly monitored and that priority should now be given to the indirect or land-use implication of control including socio-economic evaluation.
16. The value of retaining a range of viable tsetse control methods, including chemical control and SIT, was accepted and the need to adapt these to specific situations was given greater priority than the search for new methods. The potential of odour bait technologies was highlighted.
17. Apart from greater emphasis on community participation and land use, few radically different issues were raised. It is increasingly accepted that eradication will not easily be achieved and that realistic targets must be set. The value of computerised techniques and satellite data to clarify our vision of extensive and intricate epidemiological situations was recognised; the importance of regional collaboration stressed.
18. The Second Meeting of the Inter-Secretariat Coordinating Group (1991) recommended that FAO should:
* play an active and strengthened role in the promotion and coordination of tsetse/trypanosomiasis control activities;
* become more involved in data collection, analysis and dissemination to Governments, promoting trypanosomiasis control as an element within a multi-disciplinary approach to rural development.
* should seek long term funding, for a well justified (operational research) programme and raise the profile of the Trypanosomiasis Control Programme.
PRACTICAL CONSIDERATIONS RELATING TO SUSTAINABLE TRYPANOSOMIASIS CONTROL AND AGRICULTURAL PRODUCTIVITY.
19. There are many researchers, control authorities and donors seeking to overcome national or regional problems in what they, with all sincerity and commitment, feel is an appropriate manner. A vast amount of information is generated by these various participants but it is disparate and not easily accessible.
20. Computerisation must be central to the 'development of a systematic approach to tsetse and trypanosomiasis control'. It will require specific research and training. If its full potential is exploited to understand the magnitude and ramifications of trypanosomiasis and the farming systems it constrains, it could, together with improved tactical use of existing control methods, provide added impetus to the lumbering trypanosomiasis control machinery which seems to be losing its way.
21. Some practical considerations which will enhance ‘the development of a systematic approach to tsetse and trypanosomiasis control’ are listed below for different levels of intervention.
(a) Strategic considerations:
Computerisation to define and quantify trypanosomiasis distribution and its effect on agricultural production systems.
22. Recent improvements in computer technology has provided the facility for storing and accessing huge amounts of information at prices which are now well within the reach of third world countries. Also, satellite remote sensing, which gives a visual image of ‘real time’ vegetation distribution over large areas is widely available and affordable. Pioneering work at Oxford University uses both to define potential tsetse habitats and by correlating with human and livestock distributions quantifies epidemiological risk.
23. The use of remote sensing to define tsetse distributions is in its early stages but the facility to redraw and continuously update tsetse distribution maps will be of enormous value. Although highly specialised inputs are required initially, reliable tsetse distribution and epidemiological risk mapping is ultimately dependent on ground validation and will require local involvement. National archives will provide the life blood of any in-country, regional or international data set and these will be most effective if (a) based on standard computer technology and (b) centrally coordinated.
24. Remote sensing can also be used to define land use patterns which in turn are the frameworks of farming or production systems. Geographical information systems (GIS) provide the ideal vehicle for overlaying these and other layers of spatial and temporal information including vegetation, climate, topography, human, livestock and (other animal) disease distributions; in effect the very parameters which characterise production systems. These ‘layers of data’ can then be correlated to reveal how land use patterns change over time, how natural resources such as woodlands and wetlands are affected by changes in agricultural practice and how land use changes are affected by tsetse control. Ground validation and in-country inputs will again be essential.
25. Computerisation and computer literacy underpin the facilities which now exists to quantify and better understand epidemiological risk, to define and analyse farming systems and the factors which constrain their productivity, to measure the socio-economic and environmental impact of tsetse control. They do not, however, provide a magic or even easy solution to the problems of trypanosomiasis.
26. To focus computer technologies on trypanosomiasis problems and develop operational skills in Africa will require a concerted international effort. It will initially require international research institutions such as ILRAD, Oxford University, CIRAD and NRI to develop systems in collaboration with national institutions and control authorities and eventually to transfer these to in-country users. It will require these users to be equipped with the hardware, software and skills. It will require adequate funding and skilful coordination. Specific research in the fields of environmental science, data management and socio-economics will need to be instigated or expanded with training for senior managers in similar fields plus training for technicians to create and manage the systems. This training will probably be in addition to that already carried out in support of tsetse and trypanosomiasis control.
27. FAO have the mandate to coordinate trypanosomiasis research and control. If the Animal Production and Health Division is to promote a systematic approach to tsetse and trypanosomiasis control it will need to improve its own data management system and develop the capability to provide guidance to the member states. This will require dedicated technical staff.
28. An international programme of this magnitude will not succeed without adequate financial support and FAO should begin by submitting a costed proposal to donors, particularly those institutions represented on the Coordinating Group e.g. the EC, UNDP and World Bank.
29 Technical support should be provided by a committee of international research institutions, under the chairmanship of FAO. This should assess data management systems, the current state of remote sensing and GIS research relating to tsetse/trypanosomiasis and identify specific research and training requirements. This committee should then provide technical back-stopping for the programme. UNDP might be approached as an appropriate source of funding.
(b) National/regional considerations:
In-country data management and regional data exchange to understand farming systems and the role of testse/trypanosomiasis control in land-use planning.
30. In-country data management and regional data exchange can also provide a firm platform for sustainable tsetse and trypanosomiasis control.
31. Data management at this level differs, but is complementary to that described in (a) above, in that it is more concerned with understanding specific farming system dynamics, previous control activities and, where applicable, why they failed. Veterinary departments throughout Africa already collect this data but it is kept in many disparate forms, usually printed reports and maps. Unfortunately the amount of data collected in inversely proportional to its usefulness if it is not readily accessible. Computerisation of veterinary departments records and the use of systems such as GIS would again enable control authorities to utilise information in a much more constructive manner and develop sound, repeatable strategies.
32. Standardisation would enable national authorities to exchange data and would greatly facilitate regional collaboration. Programmes such as the RTTCP were instigated for this very reason.
33. Efforts should be made to raise the computer literacy and improve the data management of veterinary departments throughout Africa. National or regional research and training will again require additional inputs to specifically address this objective. Socio-economics research is particularly pertinent to increasing agricultural production, senior staff will need to understand the system and utilise the outputs, technicians will need to be trained to manage the systems.
34. The responsibility for developing veterinary epidemiology units ultimately lies with national authorities but bi-lateral and multi-lateral donors will inevitable be more inclined to support if these help to (a) define the full economic cost of trypanosomiasis and (b) formulate realistic multi-disciplinary control strategies.
35. Dissemination would be greatly improved if these computerised data could be collected, analysed and redistributed by a central coordinating body; again this should ideally be FAO/AGAH. Regional programmes might also be encouraged to give higher priority to data management and to become more closely aligned with the Expert Panel and Commission recommendations through a second committee of major or regional operational control programme representatives. This would advise on regional management and strategic planning at a technical level.
36. Regional tsetse and trypanosomiasis control programmes currently obtain most support from the EC and, in the southern Africa (RTTCP) programme at least, the EC strongly emphasises land use and rural development. The EC might therefore be approached to fund this technical committee.
(c) Operational considerations:
37. Computerised techniques and a systematic approach will increase our understanding of trypanosomiasis, how it effects land use and how its control can be integrated into strategies aimed more broadly at increased agricultural production. Ultimately this ‘control’ still depends upon the techniques used and as discussed above these are not working too well. In practical terms there is a need to pre-empt declining interest in odour bait technologies which continue to proliferate without significant lasting success, to rejuvenate established chemical control methods which have become prematurely redundant, to improve the efficiency of chemotherapy in the face of increasing drug resistance and little hope of replacements.
38. Recommendations aimed at improving this particular situation include making better use of established methods through adaptive research, aiming for control rather than eradication, involving the local community.
(i) The use of realistic, achievable control objectives based on established control techniques,
39. Land use plans are designed to increase productivity by making the best use of the resource available, improving agricultural practices, putting marginal lands to good use etc.. Social, economic and environmental awareness is essential if the outputs from these activities are to be sustained. The balance that has to be achieved is that the total cost of alleviating constraints to production (including trypanosomiasis and indirect costs resulting from any negative impact of its control) does not exceed the beneficial value. This should dictate the expenditure on trypanosomiasis control and it probably does where the system is self sustaining; perhaps depending on chemotherapy or trypanotolerant animals. This has seldom been the case where there has been government or international intervention to control tsetse flies.
40. Most large scale tsetse control operations have tended to aim for eradication which is understandable if this is considered an end in itself but eradication is difficult to achieve with any certainty with any single technique (Allsopp 1992). If the disease is accepted as one of many constraints to agricultural production and its control consequently integrated with other disease controls, improved livestock nutrition, crop protection etc. i.e. as part of a land use plan, then eradication need not be the aim.
41. The cost of virtually all tsetse control methods could be significantly reduced if designed to reduces rather than eradicate tsetse populations. SAT, odour bait technologies and cattle dipping are especially well suited for limited control rather than eradication; particularly if used in a truly integrated way. Aerial spraying has effectively been discarded, largely on the grounds of expense, despite its capability to reduce tsetse populations to the verge of extinction within three months. The known capabilities of these techniques could be used with much greater certainty if not aimed at eradication.
42. It can be argued that if targets works why bother with SAT in the first place. This arguments holds if they do work and fairly quickly. The same argument could also apply to SIT where the high cost of rearing colonies of sterlite flies is defrayed by knocking down the tsetse populations by SAT. The determining factor of any such combined approach is the total cost, over whatever period of time it takes to achieve the objective. Economic analysis is therefore clearly important.
43. The point here is not to compare the merits of the various techniques; they all have their advantages and disadvantages. It is to highlight the potential value of combining proven techniques in a synergistic manner and with the ultimate objective of acheiving a level of control which ceases to be a major constraint. If the result is increased agricultural production, the recurrent cost could be absorbed accordingly, perhaps as a local community expenditure.
44. This approach would require field testing. It would probably involve a government or institutional input if ground or aerial spraying were used to make the initial reduction; although this could be undertaken by the private sector. Local community management of the ‘mopping up’ or containment could be encouraged. It would need to be carefully evaluated with particular emphasis on social and economic monitoring. It would require a considerable amount of organisation in this trial stage and would perhaps be most appropriate where a large, flexible control programme is already underway. The Busoga area of Uganda or Kabwe area of Zambia would be ideal sites for such a trial.
45. The acid test of such an approach is whether it can ultimately be maintained, either partially or fully, from the production system's own resources i.e. by the local community.
(ii) The role of the private sector in tsetse/trypanosomiasis control.
46. Community participation is perhaps a misnomer. It tends to refer to relatively small trapping operations managed at the farmer or village level. What actually need to be considered is how (or if) responsibility for tsetse and trypanosomiasis control can be switched partially or wholly from government or donor support to the private sector. In this context the private sector includes resource poor farmers on communal farming lands, commercial farmers and private industry which does, or would like to, provide a control service.
47. In the long term, sustainable agricultural productions will depend on the stability and effective use of resources in production systems. FAO and WHO mounted a major operational research programme on trypanosomiasis in the Lambwe Valley in the 1970s. Since then there have been numerous other efforts, using a variety of techniques, to eliminate the disease from this relatively small area but it still exists. GTZ supported years of helicopter spraying in Cameroun, they no longer do and tsetse have returned. Zimbabwe has 70,000 targets deployed as their first line of defence to protect areas cleared of tsetse after years of successful chemical control. The goverment run operation is currently dependent on EC support and even with this combined effort, tsetse are slowly filtering back.
48. Perhaps the most important policy change needed in trypanosomiasis infested Africa is to transfer the responsibility for control from government to the private sector. There will always be a government role and inputs from international donors will always be valued but sustainable agricultural production and trypanosomiasis control should not remain for ever depend on either.
49. Clearly this is not a short term objective nor is it likely or essential that it be adopted universally but based on sound economics, epidemiological understanding and land use practice i.e. based on the results of (a) and (b) above it is a realistic long term policy.
50. Countries wishing to promote private sector involvement in trypanosomiasis control could be encouraged to register their interest in an international ‘restructuring’ programme. which should again be coordinated by FAO, and which the World Bank could perhaps be persuaded to support.
51. The programme would involve the identification of veterinary and tsetse control practices currently within the public sector which are appropriate for privatisation; with particular emphasis on the residual role of public sector institutions and how these should be strengthened. The concept of privatisation and its socio-economic implications would need to be clearly defined, evaluated and aligned with individual government policies. Specific research and training could then be targeted at different intervention levels. Thus social scientists would play a greater role in developing farmer participation and extension workers should be trained to support communal and commercial farmers. Trainers would need to be trained. Technical and probably financial inputs would be required to help the private sector develop an operational control capability.
52. A third committee with a strong social science and economics flavour might usefully advise FAO and government policy makers on privatisation, cost recovery schemes, appropriate institutional stregthening, farmer participation etc.. This committee would initially help FAO define a programme perhaps entitled ‘private sector development of sustainable agriculture in marginal, tsetse infested, areas’. It would again provide back-stopping support should the programme attract support and be put into implementation.
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