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Use of attractive devices for tsetse survey and control

Chapter 8: Economics and management of control

General principles

Whilst the discussion that follows is mainly concerned with animal Trypanosomosis, much of it can be applied to control of the human disease. Given the restricted financial situation of many government departments, any measures that can improve public health will reduce the burden on overstretched medical facilities. Until recently, the high cost of tsetse control has largely restricted its use to where external funds are available. All too often such funding has been in response to crises and very rarely have the control measures been sustained once the crisis is over. Nevertheless, in many instances the short-term benefits achieved may be economically justified. If long term control is to be achieved it cannot depend indefinitely on external support.

If control of any pest is to be worthwhile, then the costs of that control must be less than the benefits. In an economic analysis, these costs and benefits are expressed in monetary terms over a period of time. A benefit-cost ratio can then be calculated, if that ratio is less than one, the costs are greater than the benefits; if it is greater than one, the benefits exceed the costs. Obviously, the higher the benefit-cost ratio, the better.

The direct costs of a tsetse control operation are relatively easy to estimate. For a trap/target operation executed by a government department, they would include costs for headquarters and administrative overheads, survey and planning, field camp establishment and operation, development of access roads, materials and chemicals for the targets and costs for deploying and servicing targets. They would also include both manpower and transport costs for these various activities.

Benefits are much more difficult to estimate, and for control of human Trypanosomosis, methods are usually compared on the basis of costs alone. For animal Trypanosomosis it is difficult, though not impossible, to estimate the benefits in monetary terms.

These benefits can be divided into direct and indirect benefits.


(a) Direct benefits
These result from a reduction in the deaths of livestock caused by the disease, mortality, and in its chronic effects, such as poor growth rates and abortion, morbidity. In addition if livestock are already being kept in the area on drug regimes, there will be a direct reduction in drug costs.

(b) Indirect benefits
The main indirect benefit of tsetse control is that it allows more land to be used for agriculture. Sometimes tsetse prevent susceptible animals from being kept in an area at all; in other areas they restrict access to important dry season grazing grounds. In the latter case if the constraint is removed productivity will increase because nutrition is improved.

Such benefits will only materialise if the land is not overstocked; if it is, productivity will decline again and all benefits of tsetse control may be lost. Traditional methods of rangeland use, e.g. pastoralism, are probably better adapted to semi-arid rangeland conditions than ranches with fixed stocking levels, and great care must be taken when introducing tsetse control that appropriate mechanisms of range management are in place.

Another very significant indirect benefit is that tsetse control may allow oxen to be used for traction in arable farming. In some parts of Africa, this can constitute one of the major economic benefits of tsetse control. Within a predominantly arable farming system, cattle can also be zero-grazed, fed on crop residues in an enclosure. Whilst a third benefit may be the protection of cleared and productive areas from tsetse reinvasion.


Economics of control versus eradication

Various studies have been done to compare the economics of control versus eradication. A benefit-cost study was carried out on a successful eradication programme, using residual insecticides, in northern Nigeria. Both at local and national level the benefit-cost ratios were very high (2-7), mainly as a result of the extra meat produced. The operation was still highly profitable even if it was assumed that one of the species, G.m. submorsitans, would have died out anyway as a result of increasing population pressure.

The above example refers to a situation in which isolated fly belts are eliminated near the edge of the tsetse flies' natural distribution. The situation is rather different over much of Africa where sustainable eradication is not feasible, and barriers have to be maintained. A detailed study has been carried out, in Burkina Faso, comparing local eradication by helicopter application of residual insecticides, or the sterile insect technique supported by barriers, with control using insecticide-impregnated biconical traps or chemotherapy.

Chemotherapy was more profitable at low challenge levels but chemoprophylaxis was not an economic alternative to tsetse control in medium and high challenge situations. Comparing the different tsetse control strategies, the sterile insect technique was always less profitable than the other two methods. The trap control method was more profitable over a 5-10 year period, but for longer periods local eradication with insecticides was slightly more profitable.

The analysis also considered non-monetary aspects, such as the sustainability of the barriers, ease of technology transfer to the local people and environmental effects. In these respects the trapping approach was clearly superior, local eradication was only economical if the barriers could be maintained. Trapping used a much lower level of technology and caused no pollution. Overall, control by trapping was viewed as the most favourable option, and if eradication could be achieved by this method, the economics would be even more favourable.

The conclusions of this study do not necessarily apply in all situations, and more studies need to be carried out. However, it does indicate that with the use of traps and targets either local eradication or long term control of tsetse can be economically viable, as they can using other techniques, and that the choice really depends on operational factors such as the ability to maintain effective barriers and on technical considerations.

When making comparisons between techniques the effectiveness of each over a period of time must also be considered, for example, control may require sustained efforts over many years and in some instances the initial short term higher cost of eradication may prove more profitable.


Costs of trap/target operations

The costs of some trap/target operations have been quantified in recent years, and two examples where this has been done will now be examined.

In Zimbabwe targets have been used for local eradication of G. morsitans and G. pallidipes in both flat and rugged terrain. Costs have been estimated for targets and odours, vehicle and manpower costs for deployment and servicing, and construction and maintenance of unsurfaced access roads. In this analysis other costs were omitted, including those for survey and monitoring, planning and mapping, establishment and running of field base camps, administrative overheads at headquarters and staff training. This was done on the basis that all tsetse methods have these same overheads, although this of course is only true for government managed operations.

The cost per target per year for materials and odour baits is shown in Table 8.1. The annual costs for materials are based on their initial cost divided by the number of years they may be expected to last. The overall cost included a foreign exchange component of just over 50%. The 10% loss factor was included to allow for damage by wild animals, fire and theft.

Table 8.1 Costs per target per year in Zimbabwe at 1988 prices (originally quoted in Zimbabwe dollars and converted to US$ at rate of 1 US$ = 2 Z$)
Source:Barrett, J.C. (1991)


Vehicle and manpower costs for deployment and servicing the targets were then added to this. A target team comprising about 24 staff was estimated to cost about $22,500 per annum for wages and other allowances. Transport for this team comprising a lorry and a landrover was $8000 per annum, giving a total of $30,500 per target team. The costs per target per year depended on the number of targets that could be deployed and serviced each year by a team, and on how frequently targets required servicing.

The costs per square kilometre were then estimated on the theoretical basis of 1 target/km2 for eradication of G. pallidipes and the practical basis of 4 targets/km2 for G. morsitans. The indirect costs for the construction and maintenance of access roads, estimated at $15-30/km2 for flat terrain and $100-150/km2 for rugged terrain, were then added to these to give the total costs shown in Table 8.2. Costs for aerial spraying (SAT) and ground spraying are also given for comparison. However a comparison of the technical effectiveness of the methods to achieve eradication has not been considered.

Table 8.2 Comparative costs of targets versus aerial and ground spraying in Zimbabwe at 1988 prices (originally quoted in Zimbabwe dollars and converted to US$ at rate of 1 US$ = 2 Z$)
Source:Barrett, J.C. (1991)


For comparison with community-based programmes, the costs of central management would need to be included, such as field camps, planning and survey, training and overheads. These are likely to be very considerable, but no estimates are available. It must be emphasised, however, that these are costs for local eradication over about a two year period. If eradication is achieved then of course all costs cease except those that may be required to prevent reinvasion. Although the annual costs are higher than those of a control campaign of less intensity, taken over a longer time they could be considerably cheaper, thus, every situation must be considered on its own merit and comparisons between differing situations and technical approaches become complicated.

The second example is a cost analysis for a community-based control operation directed against G. pallidipes over an area of about 500-1000 km2 in Kenya. The situation here is quite different, and the analysis includes all management costs except those for training. These would be high for just one community, but if staff in many communities were being trained during the year by central government, the costs would be much lower.

Tsetse eradication is not feasible in the area because of reinvasion pressures. This analysis assumes tsetse control to a sufficiently low level that drug costs would be negligible.

Costs for trap materials and odour baits are given in Table 8.3. Supports are made from locally cut wood, and labour costs for these are included in staff expenses. Acetone is purchased locally, but the other odour, cow urine, is free. At an average trap density of 2/km2, the cost of these materials is $15/km2 per annum

Table 8.3 Costs per trap per year in Kenya at 1991 prices (originally in Kenya shillings and converted to US$ at rate of 1 US$ = 29 Kshs)
Source:Olkiramatian and Shompole Community Development Project (1991) (Unpublished Report).

Two small field camps are used, consisting of a metal hut in each for storage purposes. These cost about $790 each and last about 10 years, giving a cost of about $160 per annum. Together with fencing and maintenance this comes to about $200 per annum or $0.4 per km2 per annum.

For five regular staff, salaries come to $4140 per annum plus about $1000 per annum for casual staff, giving a total of $5140. This gives a cost of about $10.3 per km 2 per annum. Staff duties include survey, monitoring, track cutting, trap deployment and servicing.

Transport is provided by a Suzuki jeep at $13,800 (duty paid). Assuming a lifespan of 5 years, depreciation costs come to $2760 per annum, with running costs of $2500 per annum. Total for transport is therefore $5260 per annum or $10.5 per km2 per annum.

Adding these various costs together, the total comes to $36.2 per km2 per annum. Of this total, 29% is comprised of transport. In the area described a motorised vehicle is essential because the human population distribution is dynamic being determined by rainfall, and the high densities of game animals, including buffalo and lion. In other areas, bicycles or motor bikes would greatly reduce the cost.

There are about 15,000 cattle being grazed in the area for all or part of the year. Chemotherapy is widely if erratically practised, and it is estimated that an average of 2-4 chemotherapeutic doses are administered annually to each animal, more in high challenge areas, less in low challenge areas. At an average cost per treatment of $0.5, this gives a total cost of $15,000-30,000 per annum or $30-60 per km 2 per annum.

Hence annual tsetse control costs will not exceed present annual chemotherapy costs, and may well be much lower. Despite the present chemotherapy, losses are still high at times of drought when the animals are stressed and productivity is much reduced. Further benefits will come indirectly by making present high challenge areas available for grazing during drought years.

These two examples are sufficient to demonstrate that traps and targets are no more expensive than other forms of tsetse control, and if organised on a community basis may be made cheaper.


Costs of insecticide-treated livestock operations

There is as yet little published data on the costs of insecticide-treated livestock for tsetse control operations. Reported costs have been very low at only $27/km2 for dipping with deltamethrin (Decatix(R)), where a dipping infrastructure already existed, and $70/km2 for pour-on at 10 head of cattle per km2. Cases of Trypanosomosis declined to zero after about a year. However, no costs of application were included as the cattle were already being dipped for tick control.

Trials in other countries have generally been carried out over much smaller areas, with all the associated problems of tsetse reinvasion. Studies carried out over 50 km2 on Galana Ranch, Kenya, using pour-on did reduce the incidence of Trypanosomosis and increase live weight gain of treated animals. An economic analysis suggested a positive benefit-cost ratio of about 1.2; a sensitivity analysis suggested that only a small increase in the cost of the pour-on would reduce this to 1, but did not include the additional benefits derived from simultaneous control of tick borne diseases. Further field trials and technique assessment are needed to evaluate its potential for eradication and to determine the number of treated animals required per unit area to produce a result.


Management systems and community involvement

The traditional approach
In the past most tsetse control in Africa has been managed and carried out by Central Government through a Tsetse Control Branch. The main exceptions are a few large commercial ranches, but even there, chemotherapy or chemoprophylaxis has generally been used against the disease rather than tsetse control.

If eradication is feasible, then such centralized management is the only viable approach, especially since eradication may involve regional cooperation. The new techniques, however, offer possibilities for new management approaches. This is already underway in several countries.

In most situations the use of traps or targets require, at the very least, a high degree of community education to reduce theft of traps and targets. Such community awareness can be extended further to community participation, involvement of local people in control activities, and even community-based systems, management and finance by the local community, and these aspects will now be covered.

Community awareness
If traps or targets are to be deployed, it is essential that an effective community education programme is carried out, whether or not the community is to be actively involved in the operation.

There are various ways in which this can be done:

(a) Holding of meetings with local people
Within a relatively small or sparsely populated area the best way to inform the local people about the intended activities is to visit them individually. In practice, however, this is rarely possible, and the next best means is to hold group meetings. Ideally this should be done by local leaders who know their area and the local language or dialect.

A trap or target of the design to be used should be taken to the meetings, and set up for people to see. Several small meetings are always better than one big one, so that people feel free to ask questions. Meetings should be held at times to allow people in paid employment to attend.

(b) Talks to schools, women's groups etc.
It is important to reach all sectors of the community, not only men, since it may be the women or children who have most contact with the traps when fetching water, firewood or herding cattle. Talks to local schools or women's groups may succeed better in this respect than general meetings.

Schools are always grateful for any educational materials, especially if it helps with teaching their normal syllabus. Trap-making competitions are always popular, as are models, posters, and work books. T shirts, badges or baseball caps with pictures, logos or simple messages, are popular and help spread the message. Any means of involving people in maintaining or running the control can help. Where people are settled, advantage should be taken of existing groups to help maintain and protect the traps/targets.


(c) Production of posters
Meetings and talks can be very effective within a relatively closed community. If, however, other people are regularly passing through, they will not have attended the meetings and will not know what the traps or targets are for. Here, posters can be helpful, although they have to be very carefully produced.

As far as possible the message should be put over using pictures, any text should be in both the local and national languages. Poster designs should be checked with local people before large numbers are produced. Posters should be produced in materials that will survive the weather and displayed at various meeting places including markets, shops, schools, churches and water sources.

(d) Use of the media
For large-scale programmes, it may be necessary to use the mass media, especially the radio, to reach enough people. Even in rural areas many of the community will own a radio. Interviews in the field are more interesting than ones conducted in the studio.

Community participation
In many control operations, the government maintains responsibility for management and encourages the community to become actively involved, either through trap manufacture, deployment or servicing. This for success requires more than education, it also demands community motivation.

The situation and the approach differs in human and animal Trypanosomosis foci. Where human Trypanosomosis is prevalent, everybody is a potential participant, but even in outbreak areas it is likely that only a small percentage of the people will have suffered from the disease, or have family members or friends who are affected. Moreover, there is no immediate direct financial benefit from participating. Hence considerable community education and motivation is required.

In the case of animal Trypanosomosis, only livestock owners will usually be prepared to participate. If they constitute the majority of the population, there is no problem, as they will probably be immediately enthusiastic in order to gain personal financial benefits. Alternatively if many people are arable farmers they may be neutral, or even hostile, to tsetse control. This hostility may derive from feelings that livestock owners will take over their land if tsetse are controlled.

Community participation is also much more successful if human populations are sedentary rather than migratory, and if they own their land and thus have the incentive of directly benefitting from the activities. In regions where migratory seasonal movements occur considerable theft and damage may result as migrants will not appreciate the purpose of control or obtain any personal gain from the results.

Community participation is sometimes viewed as a source of free or cheap labour. This is not a good approach. If local involvement is to be secured and sustained the benefits must be convincing to the participants and exceed the value of labour and other inputs.

It is best if some people in the community are given paid employment in the control operations, in addition to any self-help component. This will not only provide employment, but will enable those employed to be trained in more depth on the approach. They can then spearhead community motivation, and act as a focus for these activities.


Community-based systems
Rather than just participating in tsetse control, there is considerable scope for communities to take over the management of these activities. In this situation, governments may have a vital facilitating role in providing education and technical training, whilst the donor role becomes one of providing initial capital investment. Tsetse control rather than eradication is more viable for this approach, since the initial investment required is likely to be much lower and the technological demands reduced.

Clearly, all of what has been said previously about community education and motivation also applies here. In addition, some management structure is required, depending on the situation. If people are buying their own traps/targets and operating them on their own farms, then a fairly loose structure based on voluntary inputs may suffice.

As well as requiring a management structure, any community would also have to have a means of generating income to pay for the tsetse control. Even if investment were provided initially by external sources sooner or later the operation would have to be sustainable from local resources.



The sustainability of control depends critically on the cost-effectiveness of the approach. Do the benefits really exceed the costs? If they do, then the operation is inherently viable but may still fail, especially if the direct beneficiaries are not contributing significantly to the cost of the operation or are not convinced of the personal benefits.


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