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Economics of trypanosomiasis control: Research implications

P. Itty

Department of Agricultural Economics,
Swiss Federal Institute of Technology,
ETH Zentrum SOL, 8092 Zurich, Switzerland


Introduction
Development of research programmes
Implementation of the research programme
Evaluation of the research programme
Profitability of trypanosomiasis control
Outcome of the research programme
References


Summary

The paper reviews past research on the economics of tsetse and trypanosomiasis control in rural cattle production systems in tsetse-infested areas of Africa. A comparison is made of the trypanosomiasis control methods using trypanotolerant cattle and/or chemotherapy in Ethiopia, The Gambia, Kenya, Côte d'Ivoire, Zaire and Togo. The trypanosomiasis control methods were distinguished according to the level of investment high initial capital investment (aerial and ground spraying sterile insect technique, and importation of trypanotolerant livestock); and high recurrent cost methods (traps and screens, deltamethrin treatment of cattle, trypanocidal drugs and indigenous trypanotolerant cattle). The second set of methods were found to be less risky and more flexible as costs and benefits flow in parallel and operations can be implemented by the local population.

Introduction

The disease and its impact

Trypanosomiasis is evident in roughly 10 million km² in 37 African countries and is a major constraint to the development of livestock production and mixed farming. Estimates indicate increases of 16% and 14% in meat and milk production, respectively, following trypanosomiasis control (Jahnke et al, 1988). The tsetse-infested area covers one-third of the land area in eastern and southern Africa (Table 1). The threat posed by the disease in the region is of concern particularly in the subhumid zone, which has the greatest potential for agricultural development. The extent of the infested area often increases and trypanosomiasis-related problems are severely exacerbated in countries that are torn by war or civil strife, as bush and vegetation thrives on land left fallow during disturbances. This often leads to a vigorous advance of the fly, threatening established human and livestock populations. The expansion of the tsetse belt has also been reported in the case of Zambia (Putt et al, 1988).

Table 1. Tsetse infested area in continental eastern and southern Africa.


Land area ('000 ha)

Tsetse infested area ('000 ha)

Share of tsetse infested land

Eastern Africa

355512

103936

29.2%

Burundi

2565

2560

99.8%

Ethiopia

122190

10997

9.0%

Kenya

56969

9628

16.9%

Rwanda

2495

2490

99.8%

Somalia

67734

2886

4.6%

Tanzania

88604

64061

72.3%

Uganda

19955

11314

56.7%

Southern Africa

381945

135997

35.8%

Angola

124670

37650

30.2%

Botswana

56673

2380

4.2%

Lesotho

3035

na

na

Malawi

9408

811

8.5%

Mozambique

78188

58250

74.5%

Swaziland

1720

na

na

Zambia

74339

30107

40.5%

Zimbabwe

38687

8999

18.1%

Eastern and Southern Africa¹

737457

239933

32.5%

1. Excluding Lesotho and Swaziland.
na = not available.

Source: FAO (1989); ILCA (1991).

Control methods

Control methods can either be directed against the vector, the tsetse fly, or against the parasite itself, the trypanosome. Vector-control methods include ground and aerial spraying of insecticides, the Sterile Insect Technique (SIT), traps and targets and the use of deltamethrin acaricide treatment for cattle. Parasite control methods include trypanocidal drug treatment and the use of trypanotolerant livestock. Avoidance of the areas infested also constitutes a means of dealing with the disease, as does the destruction of the natural habitat of the fly when land is cleared for settlement in response to increasing human population pressure.

The term trypanotolerant in livestock is generally applied to small populations of cattle, sheep and goats found in West and central Africa which possess some degree of resistance to trypanosomiasis (Trail et al, 1989). Trypanotolerance in indigenous eastern and southern African breeds should be further investigated if these are to receive the same recognition (see ODA/KETRI, 1991). In the eastern and southern African region, control operations have been undertaken since colonial times and important efforts are being currently deployed in a regional programme covering Zimbabwe, Zambia, Malawi, Botswana, Angola and Mozambique.

Previous research

In the past, the prevailing idea was that livestock losses attributable to trypanosomiasis were so great that any control effort was justified (Jahnke, 1974). This could explain (but not necessarily justify) why studies on the economics of trypanosomiasis control are recent and scarce as compared with the vast amount of literature on biological aspects of the disease. Allocation of resources has nevertheless made it essential to have economic appraisals. Table 2 presents an overview of major publications on the subject. The following points summarise the literature review by Itty (1991):

· Nearly 20 years after Jahnke's pioneering work in 1974, literature on the economics of trypanosomiasis control remains scarce.

· Studies on the economics of trypanosomiasis control for small ruminant production are almost non-existent; those undertaken (Griffin and Allonby, 1979; Kanyari et al, 1983; Morkramer et al, 1988) offer only limited information.

· Although results stricto senso are site and time specific, implications can be drawn for other regions, at other times. Research is therefore applied as widely relevant.

· The costs of control methods have most often been well accounted for, whereas benefits have been incompletely assessed. In almost all cases, quantitative data on cattle production were not available and the empirical quality of benefits fell short of costs. Indirect benefits following control (mixed farming development) were only assessed in the case of Nigeria (Putt et al, 1980; Shaw, 1986).

· The economics of the use of trypanotolerant cattle and trypanocidal drugs were not satisfactorily evaluated (Brand!, 1988) and hence comparison of methods were not complete.

· Adequate appraisal of dynamic biological systems with generation intervals of longer than one year requires some form of simulation model but only a few studies (Straw, 1986; Brandl, 1988; Itty et al, 1988) accounted for the dynamics of livestock production systems.

Table 2. Overview of literature on economics of tsetse and trypanosomiasis control for cattle production.

Various studies suffered from methodological shortcomings in applying a cost-benefit analysis. Except for Jahnke (1974), no scientist performed a rigorous social-level analysis using shadow prices to examine costs and benefits to the national economy. Since costs and benefits differ according to the participant whose perspective is examined, social-level analysis using shadow prices¹ is an important complement to producer-level (private-level) analysis using market prices.

1 Shadow prices are used to set the true values of items to the overall economy. They basically eliminate distortions due to market imperfections and missing markets for certain inputs and outputs. Such distortions appear in market prices and include elements such as taxes, subsidies, currency overvaluation etc which are often found in developing countries. (See Itty and Bidaux (1991) for an introduction to the subject of cost-benefit analysis or Gittinger (1982) for a more comprehensive coverage).

Development of research programmes

Conception of the research programme

The study is part of a wider research project undertaken by the African Trypanotolerant Livestock Network (ATLN). Its aim is to provide baseline data for livestock development in tsetse-infested areas and to evaluate different methods for controlling trypanosomiasis. The network, initiated after a survey of trypanotolerant livestock (ILCA/FAO/UNEP, 1979), is coordinated by ILCA with the close involvement of ILRAD. Biological data collection and field work are largely carried out by scientists working for national agricultural research systems (NARS), often with support from donor agencies. ATLN collaborates with national governments and ministries of nine countries in which sites have been established since 1983. These sites were selected on the basis of livestock breed, level of tsetse infestation, level of trypanosomiasis risk, management strategy (ranch, station and village) and collaboration with national governments and research organisations (Trail et al, 1989). Data were collected on tsetse flies and animal health and productivity parameters.²

2 Additional information about the Network and biological data collection are given in the paper by G. d'Ieteren on trypanotolerance and in d'Ieteren and Trail (1988).

In 1987, it was decided that, with the increased availability of cattle productivity data, an economic component could be added to the biological study, which encompassed entomology, livestock production, veterinary science and genetics. Between 1988 and 1991, case studies on the economics of village cattle production in tsetse-affected areas of Africa were undertaken in seven sites (Itty, 1991). At the two East African sites of Ghibe in Ethiopia and Muhaka in Kenya, the cattle production systems used susceptible East African Zebus under trypanocidal drug coverage. The traditional use of trypanotolerant cattle was illustrated in three West African sites: Gunjur and Keneba in The Gambia and Boundiali in Côte d'Ivoire. The introduction of cattle production systems using trypanotolerant cattle in regions devoid of bovines was examined through the cases of Avetonou in Togo and Idiofa in Zaire. A total of 50 herds or herd groups were examined (small herds had to be merged into herd groups for the purpose of biological analysis).

Objectives of the research programme

Five main objectives were fixed (Itty, 1991):

· The application of an appropriate methodology to evaluate the economies of livestock production systems and disease control. Various authors including Grindle (1985) and McInerney (1988) have reported that the application of economic theory and appropriate methodologies for veterinary economics has suffered from serious shortcomings. The approach proposed attempts to move a step further from relatively narrowly defined cost-benefit studies or a mechanistic application of prices to physical quantities (Grindle, 1985).

· Calculation of returns to scale factors of production in the use of trypanotolerant cattle and trypanocidal drugs for cattle meat and milk production.

· Investigation on the effects of social and private analyses on the extent of the adoption or improvement of cattle production systems using trypanotolerant cattle or trypanocides.

· Determination of the factors that influence social and private profitability of the production systems on the basis of inter-herd and inter-site variations.

· Comparison of tsetse and trypanosomiasis control methods, leading to a choice of strategies.

Implementation of the research programme

The study is centred around a cost-benefit analysis enhanced by a dynamic herd simulation model and rapid rural appraisal (RRA). A social-level economic analysis was conducted to evaluate the benefits and costs of the herds to the overall economy of the countries examined. A private-level financial analysis was conducted to examine the financial profits to cattle producers. Since a trypanosomiasis control programme involves several major participants (the state, the livestock development authority, producers, herdsmen traders, consumers etc) who share the costs and benefits, interest was focused on the returns to the overall economy. On the micro-level, success of a control programme rests primarily on the performance of cattle owners who are the main beneficiaries, hence the justification of the private-level analysis.

Costs and benefits were projected for a 10-year period using the ILCA Bio-Economic Herd Model for Microcomputer. The ILCA model is a deterministic dynamic model which simulates herd evolution, production and economic performance over a 10-year period from base parameters on herd structure, productivity and economic phenomena (von Kaufmann et al, 1990).3 Data collected monthly over three to four years by the ATLN were used to derive baseline biological data for each herd (milk off-take was an exception as data were recorded daily). An economic survey and an RRA conducted once at each site provided the economic data and qualitative information on the cattle systems. The focus is on returns derived from milk and meat, although it is recognised that other functions, socio-economic aspects and products of cattle are also very important, but they could only be covered qualitatively through the RRA. For the RRA information was collected from three sources: secondary data, group interviews with farmers (using a semi-structured questionnaire) and discussions with key informants. The information was cross-checked and pooled in a triangulation process (McCracken et al, 1988).

3 Correspondence concerning the model and its acquisition should be addressed to: The Head, Livestock Economics Division, ILCA, P O Box 5689 Addis Ababa, Ethiopia.

Implementation

The economic component was conducted by the author after the literature review was completed and after the methodology had been determined and the questionnaire tested. Prior to data collection, information on the planned work was sent to the ATLN field staff. One month was spent in each country for collection of economic data and socio-economic information. Economic data included the type and quantity of inputs used, information on veterinary services and market and shadow prices. For the latter, information had to be collected from ministries and resident economists (World Bank, ILCA, Harvard Institute for International Development etc), usually located in capitals, and from the literature. For the interviews, interpreters were made available by the ATLN field project. Access to local authorities, extension agents, veterinarians and other resource persons was greatly facilitated by ATLN staff.

Upon completion of the field work the herd model was adapted and finalised and the initial analysis was carried out at ILCA headquarters. Close contacts and discussions with colleagues in ILCA's Livestock Economics Division and at the ATLN coordinating office were most useful as methodological improvements were made and biological data re-analysed to correspond to the needs of the economic analysis. This resulted in delays in the final analyses, which were carried out in Switzerland. However, the quality of results was considerably enhanced.

Evaluation of the research programme

Collaboration and local institutions

The research programme benefited considerably from being carried out under the auspices of ATLN and at ILCA. Collaboration with field staff was extremely helpful in obtaining the information required and the use of local ATLN infrastructure (computer at some sites, vehicle, office) permitted smooth operation. Discussions with NARS, government officials and extension services, ATLN field staff and ILCA staff etc were most fruitful at all stages. The main problem was that the economic component was grafted onto the main biological research project and basically limited to one man's work. The lack of provision for training of local scientists in the collection and analysis of economic data was apparent. These problems need to be addressed in future.

Methodology

Through application of a herd model, proper phasing of costs and benefits could be accounted for. The period simulated by the model (10 years) was sufficient to reveal the dynamic effects of the production system, yet not too long to risk making certain assumptions. In a corresponding study, Jahnke (1974) used a 30-year projection to examine the economics of introducing trypanotolerant cattle into the Central African Republic. Changes in socio-economic environment and technical developments outdated control methods and modified expected benefits. In this case, the assumptions turned out to be far from reality: instead of the 128,000 head of trypanotolerant cattle projected for 1985, the population actually dropped to 7400 head by 1984 (Straw and Hoste, 1987). The political chaos in the country was mainly responsible for this. At the same time there was, however, a considerable influx of pastoralists with zebu cattle (under trypanocidal coverage) (Straw and Hoste, 1987).

This was the first economic study on the subject based on empirical quantitative data on livestock productivity. These data were in fact quite unique for African village conditions, regardless of the focus on trypanosomiasis. The long period over which biological data had been collected using standardised research techniques has culminated into a large data base that is extensive enough to generate a means applicability for individual herds or herd groups, thus allowing a comparison of inter-herd variation. The collection period was long enough (three to four years) to obtain meaningful estimates of reproduction and lactation yields, which are often poorly documented, if at all (e.g. previous estimates of lactation yields in The Gambia were as much as four times lower than those actually recorded). The mean actual milk off-take in the two Gambian sites was 373 kg for Gunjur and 413 kg for Keneba (Itty et al, 1992), whereas earlier estimates were 69.3 kg (high trypanosomiasis risk) and 98.9 kg (low risk) (Clifford, 1977). Some previous studies examined only liveweight gains (Wilson et al, 1975 and 1986; Logan et al, 1984), which is justified in the case of beef ranches Results show that the value of milk accruing to the relevant participant (state or producer) appears to largely determine the level of returns. In any case, the majority of the producers sell animals when cash is needed and not after a certain period of fattening. This questions the relevance of liveweight gains to such producers.

Rigorous application of social-level analysis using shadow prices and private-level analysis using market prices revealed major constraints, as illustrated by The Gambian case study of Keneba. The difference in social and private value of herd labour and milk were principally responsible for the wide divergence in results. The internal rate of return was 46% in the social analysis, compared with 26% in the private analysis. Herding costs appeared to be an important factor in increasing private profitability, as a large share of the milk went to the herders as part of their remuneration. A possible explanation for the high remuneration is offered by information collected during the RRA; this indicated that cattle owners were crop farmers, who are less knowledgeable about cattle than the Peul herders. The share contract provided the herders with incentives as they had a stake in the system (risk sharing) and they reduced supervision costs (time consuming and difficult because of the limited expertise of owners). Share contracts were widespread and similar arrangements were practiced at the other Gambian site, in Côte d'Ivoire and also in Kenya. Identification of such major constraints was only feasible through on-farm research in villages

The use of a shadow exchange rate to account for a possible overvaluation of the local currency was very important when comparing tsetse and trypanosomiasis control methods. If the overvaluation was not accounted for, methods requiring large amounts of foreign exchange (e.g. aerial spraying) appeared too cheap relative to methods requiring more local inputs (labour intensive ground spraying or traps and targets).

Since socio-economic criteria were not included in the selection of the herds or in the experimental design, test herds may therefore not necessarily be representative for the site as they were generally larger than average and, in the case of Côte d'Ivoire, often belonged to affluent absentee owners. Furthermore, a socio-economic protocol was not established from the beginning of the network. Limitations appeared as there were no time series of inputs used and prices; hence price variations or trends based on historical data and sensitivity analysis using standard errors could not be simulated. Biological data were limited to milk and meat although in Ghibe (Ethiopia), for instance, the principal purpose of keeping cattle was for animal traction. In many other sites crop livestock interactions are of prime importance. These indirect benefits of trypanosomiasis control could not be quantified because data collection was not planned; investigation of these aspects needs urgent attention. Valuable information will be shortly available in Zimbabwe (J. Barrett, Natural Resources Institute, Chatham Maritime, 1992, personal communication).

In the case of trypanotolerant cattle, the lack of historical records meant that the costs of importation and multiplication could not be accounted for in Zaire or Togo. Hence, results were limited to the economies of the ongoing production systems. In addition, further research is also required on the reasons why farmers often prefer zebus to the smaller trypanotolerant breeds when disease risk is not too high.

Profitability of trypanosomiasis control

The results provide estimates of returns to capital invested in cattle production systems using trypanotolerant cattle and/or trypanocidal drugs. On the basis of the site averages, both methods were economically and financially profitable: social rates of return ranged from 15 to 53% and private rates from 10 to 29%. Output was low but the profits were attractive as all the systems required few inputs. However, due to the growing drug resistance of trypanosomes, future application of this method is severely limited. The results also show that the disease is only one of the constraints (albeit an important one) that cattle producers face in regions with low to medium trypanosomiasis risk. To improve the production systems, information is required on other biological constraints such as feed and diseases and on the operational socio-economic context and the management of the herd. This approach would put trypanosomiasis control in a global perspective. However, a comparison of trypanosomiasis control methods can be drawn in broad terms on the basis of our results and of those of previous studies (Itty, 1991).

In the examination of the economics of trypanosomiasis control, phasing is particularly crucial because of the methodological element of discounting used in cost-benefit analysis.4

4 The underlying rationale for discounting is that a monetary unit received today is more valuable that the same cum in the future (time is money). This difference in value reflect" the opportunity cost of capital which is the foregone value of capital invested in its best alternative. Thus US$ 1 available today could be invested at the going interest rate of, say, 7%, so that in one year from now it would be worth (1 + 0.07) = US$ 1.07. By reversing this process, the value of a sum in year n can also be expressed in present-value term". The merit of the discounting procedure is that it allows payment" and receipts occurring at different times to be converted to a common standard in terms of their present value (Dillon and Hardaker, 1984; Itty and Bidaux, 1991).

One can broadly distinguish trypanosomiasis control methods according to the type of investment: those requiring heavy initial capital investment (aerial and ground spraying, the sterile insect technique and importation of trypanotolerant livestock) and those requiring more recurrent costs (traps and screens, deltamethrin treatment of cattle, trypanocidal drugs and trypanotolerant cattle when locally available). Basically, the second set of methods is less risky and more flexible as costs and benefits flow in parallel and operations can be stopped with lesser losses. An interruption could be envisaged if expected benefits were not realised or the switch to improved methods was desired. As lower initial investment and less foreign currency was required in the second set of methods it was more likely to be implemented by the local population with minimal external input (e.g. trypanocides are administered by cattle owners or by animal health assistants; community-based tsetse control can be implemented by traps as in Nguruman, Kenya (ODA/KETRI, 1991)).

It would then appear that the various techniques have specific contributions to make and that in practice a combination of control methods, determined by the prevailing conditions, might prove technically more appropriate and more profitable than the use of a single method. For instance, therapeutic drug treatments are suitable for very low risk situations with low cattle density and prophylactic treatments for cases under slightly higher risk (Itty et al, 1988). In view of drug resistance this method will be increasingly used for strategic purposes and in conjunction with other control techniques. Trypanotolerant cattle tend to be suited for situations with low to medium trypanosome prevalence as this presents few risks (no collapse of control operations). An assessment of the cost of importing trypanotolerant stock should be carefully conducted; indications suggest that this is not necessarily profitable (Itty, 1991). However, the role of trypanotolerant stock as a control method might be modified with decreasing trypanosomiasis risk due to human population pressure on land and better tsetse control techniques. Their uptake will depend on their comparative productivity once disease risk is reduced and on farmers' preference.

As the level of risk increases tsetse control tends to become the solution of choice but vector control can be undertaken in conjunction with drugs or tolerant livestock. Traps and screens seem the most profitable and promising solution, although other techniques could be of importance under specific conditions. Tsetse control is likely to be more profitable than drugs and trypanotolerant cattle, but is conditional on cleared land becoming available for cattle, a high carrying capacity, medium human and cattle population densities prior to the intervention (for cattle between 50% and 75% of the potential density (Jahnke, 1974)), and cattle having traditionally been kept by farmers who will use the land. These conditions would enable rapid establishment of both cattle and mixed farming. This rapidity ensures high benefits even when discounted and intensive or multipurpose cattle production implies an increased level of benefits (in the sites of Togo and Zaire, benefits were confined to meat which restricted revenues). Production of small ruminants might well be more profitable than cattle in sites producing only meat (Morkramer et al, 1988).

Outcome of the research programme

As the research programme has recently been completed and publications and findings are being currently submitted and presented, it is still premature to comment on implementation of recommendations and findings in trypanosomiasis control operations.

Additional and complementary work is being pursued by ATLN on the following points (B. Swallow, ILCA, Nairobi, 1992, personal communication):

· Cost-effectiveness, net pay off and riskiness of selected disease control and animal nutrition interventions;

· Economic risks and costs of trypanosomiasis in terms of its impacts on animal productivity;

· Willingness of the local community to contribute resources to tsetse control programmes; and

· Breeding practices, breed preferences and concept of the strengths and weaknesses of different breeds of cattle, sheep and goats.

References

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Barrett J C. 1989. Cost of analysis of odour baited targets used for tsetse control in Zimbabwe. In: International Scientific Council for Trypanosomiasis Research and Control, 20th meeting Mombasa, Kenya. OAU (Organisation of African Unity)/STRC (Scientific sad Technical Research Council) Nairobi, Kenya.

Brandl F E. 1988. Economics of trypanosomiasis control in cattle. Wissenschaftsverlag Vauk, Kiel, Germany.

Clifford D. 1977. An epidemiological study of trypanosomiasis in N'dama cattle in the Gambia. Paper presented at the 15th OAU/STRC (Organization of African Unity/Scientific and Technical Research Council) meeting held in Banjul 25-29 April 1977.

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