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Economic implications of the control of East Coast fever in eastern, central and southern Africa

A.W. Mukhebi and B.D. Perry

International Laboratory for Research on Animal Diseases (ILRAD)
P.O. Box 30709, Nairobi, Kenya


Introduction
Control costs
Treatment
Government expenditures on ECF control
Other indirect losses
Estimates of regional economic losses due to ECF
Limitations of current methods of ECF control
New methods of ECF control
Assessing the economics of the infection and treatment method
Limitations of the infection and treatment method
Policy issues
References


Summary

Considerable economic losses in the eastern, central and southern Africa region are caused by East Coast fever. Annual estimates are US$ 168 million including a mortality of 1.1 million cattle. The disease is conventionally controlled by acaricides and chemotherapy, however, these methods of control have become less reliable, acceptable and sustainable for a variety of reasons. These include the high cost of acaricides and drugs paid for in foreign currency, poor maintenance of dips or spray races, water shortages, acaricide resistance, illegal cattle movements, contamination of the environment or food with toxic residues and alternative tick hosts.

New, safer, cheaper and more sustainable methods based upon immunisation are being developed. At present, the only available method of immunisation is the infection and treatment method. It is currently being applied in many countries of the region, albeit on a pilot basis.

This method shows considerable advantage over the current control methods and appears to be economically viable. Individual countries need to assess the efficacy of and appropriate policies for more widespread use of the method. ILRAD provides technical backup and collaborative socio-economic assessments of the application of the method in the affected region.

Introduction

East Coast fever Cause and distribution

East Coast fever (ECF) is a form of theileriosis caused by the parasite Theileria parva transmitted by the tick Rhipicephalus appendiculatus (Norval et al, 1992). It is a major disease of cattle in 11 countries in eastern, central and southern Africa. The affected countries are Burundi, Kenya, Malawi, Mozambique, Rwanda, Sudan, Tanzania, Uganda, Zaire, Zambia and Zimbabwe. The estimated land area and cattle population affected by ECF in the region are provided in Table 1.

Table 1. Land area and cattle population affected by East Coast lever in 11 African countries, 1988.

Item

11 ECF countries

% of Africa

Human population (million)

175

29

Total land area (million ha)

835

28

Land under theileriosis (million ha)

156


Land under theileriosis of total (%)

19

5

Total cattle population (million)

63

35

Cattle under theileriosis (million)

24


Cattle under theileriosis of total (%)

38

13

Source: Mukhebi et al (1992).

Economic losses due to East Coast fever

East Coast fever causes economic losses to individual farmers and governments. Such losses can be classified into direct and indirect production losses, losses through costs incurred for controlling the disease and costs for providing research, training and extension services pertaining to the disease. Such economic losses vary widely within and among countries in both time and space, due to differences in livestock production systems, cattle types, level of disease risk, disease control policies and programmes cost and price structures.

However, due to the paucity of data on the occurrence and productivity effects of ECF, these losses are at present difficult to estimate accurately.

Direct production losses. Direct production losses can be attributed to the presence of the disease in the cattle herd through morbidity and mortality. Cattle which become severely infected usually die unless treated. Taurine (Bos taurus) cattle, their crosses and improved zebu or Sanga (Bos indicus) cattle which originate in non-endemic areas are most severely affected (Morzaria et al, 1988). Indigenous breeds are also at risk in situations where they are subjected to intensive tick control, or when they are moved from disease-free to endemic areas. Mortality rates under endemically stable conditions occur mostly in calves and vary from zero to 50% (Steak, 1981; Moll et al, 1984; Berkvens et al, 1989). Where endemic instability exists, mortality may be as high as 80 to 100% (Cunningham, 1977; Hooke, 1981; Julla 1985; Lawrence, 1992). However, these figures often are derived from localised studies and may not reflect the actual rates in larger populations.

Although mortality in indigenous cattle in endemic areas can be low, calf growth is often severely affected (Moll et al, 1985). However, controlled studies of the effects of these mild infections in cattle have not been carried out.

Animals which recover from ECF as a complication may suffer from weight loss, produce low milk yields, provide less draft power and could possibly suffer from reduced fertility and delays in reaching maturity. However, extensive studies on these types of production losses caused by the disease have not yet been undertaken. What should be kept in mind is that these animals also remain carriers and can spread infection (Lawrence and McCosker, 1981; Brown, 1985).

Indirect production losses. Indirect production losses occur when the disease acts as a constraint on the use of improved cattle. In the affected areas, farmers face a substantial risk if they try to keep Taurine or crossbred cattle due to their high susceptibility to the disease. Many farmers are therefore constrained or prohibited from utilising improved genotypes and improving livestock productivity and efficiency (Callow, 1983).

Control costs

Tick control

East Coast fever is conventionally checked by the control of the vector ticks through the application of acaricides to the surface of an animal by dipping, spraying or hand-washing to kill the tick. In areas of heavy tick infestation, cattle are treated with acaricides as often as twice a week.

In many smallholder areas, the dipping service is provided by the government through public dip tanks, either free of charge or at a highly subsidised cost. Dipping is usually compulsory at stated intervals to achieve more effective and widespread control. Even though the majority of farmers have access to this assistance, there is a significant private sector of commercial farmers, both small-and large-scale, who bear the full cost of the fight to prevent the disease.

Depending on the frequency of applications, annual costs of acaricide to farmers who are financially responsible for the purchase of these drugs ranges from US$ 2 to US$ 20 per animal (Lawrence and McCosker, 1981; de Leeuw and Pasha, 1988; Young et al, 1988; Young et al, 1990; Perry et al, 1990). To the farmers who use public dip tanks, the real cost of tick control includes loss of animal traction time and human labour for the period spent in trekking animals to and from the dip tanks, often several kilometres away from the farm.

Losses are also incurred whilst driving animals through dip tanks from stress-induced abortions, drowning and physical injury.

In addition, the constant trekking of animals to dip tanks often creates gullies and the frequent concentration of animals around the tanks leads to overgrazing, both of which cause erosion and environmental degradation.

There are further indirect economic losses which can be attributed to tick control. The application of acaricides on vector ticks through dipping, spraying or hand-washing animals contributes to the pollution of the environment and may endanger human health. This arises from direct contact, spilled or misused acaricides and also from consumption of products derived from animals treated with acaricides (Keating, 1987; Young et al, 1988). In addition, the occurrence of ticks and their control cause worry and anxiety to the farmers who have to deal with the problem on a daily basis.

Treatment

Effective treatment of ECF requires identification of the disease through surveillance and diagnosis followed by treatment of infected animals with drugs.

In much of the affected region this service is provided by governments, often free or at subsidised charges, through veterinary investigation laboratories and the veterinary extension service. Farmers who pay for the service can spend as much as US$ 10 to 20 per animal per treatment (Mutugi et al, 1988; Young et al, 1988). The relatively high cost of treatment coupled with the poor veterinary services available especially to smallholder farmers imply that only a small proportion of infected animals have access to treatment.

Government expenditures on ECF control

By providing curative and tick control services to farmers free or at highly subsidised charges, governments spend substantial sums of money annually, especially in foreign exchange, for the importation of drugs and acaricides. For instance, Kenya spent about US$ 10 million in 1987 (Young et al, 1988) and Zimbabwe spent an estimated US$ 9 million during the 1988/89 financial year (Perry et al, 1990). Even though these cost estimates include costs of tick control against all tick-borne diseases, ECF is the major disease prompting the use of acaricidal applications in much of the region (Cunningham, 1977).

Governments also spend considerable funds on research, training and extension services related to the control of ECF. In addition private firms and international organisations invest large sums of money on research aimed at developing new acaricides, treatment drugs, vaccines and other improved control methods.

Other indirect losses

There are other indirect losses which can be attributed to ECF. For instance, the depletion of scarce foreign exchange arising from expenditure for importing livestock products in short supply. In addition, losses in beef, milk and hides due to disease which reduces the supply of these products as raw materials and thereby retards the development of the livestock product processing industry. Furthermore, the 1088 of beef and milk diminishes the supply of food protein and consequently impoverishes household nutrition.

Estimates of regional economic losses due to ECF

Estimates of farm level losses from tick control and treatment have been discussed above. Country levels or regional estimates of ECF losses are few. Miller et al (1977) estimated that ECF caused half a million cattle deaths per year in Kenya, Tanzania and Uganda (Young et al, 1988).

Most recently, Mukhebi et al (1992) calculated annual economic losses due to ECF in the 11 affected countries in the region. The estimates indicate that the total direct 1088 (in beef, milk, traction and manure, in treatment, acaricide, research and extension costs) caused by the disease in the region is US$ 168 million a year (Table 2), including an estimated mortality of 1.1 million cattle. The reduction in milk production represented the greatest financial loss, followed by the cost of acaricides, traction and beef in that order.

The diminished value of beef and milk from cattle morbidity was estimated to be three times as high as that from mortality (Table 2). Similarly, the value of beef and milk losses was three times the cost of acaricide applications. Often it is the mortality and the acaricide cost that appears to receive the greatest attention and concern from those interested in controlling the disease. This may be due to the fact that mortality is more discernible than morbidity, and acaricide expense is a more direct cost than output reduction on beef and milk.

Table 2. Estimated regional losses in 1989 due to East Coast fever in 11 African countries affected by the disease.

Item

Quantity

Loss in US$ thousand

% of total loss

Beef loss, total (t)

19,428

20,607

12


- mortality loss (t)

16,246

17,232

-


- morbidity loss (t)

3,182

3.375

-

Milk loss, total (t)

97,482

78,697

47


- mortality loss (t)

9,284

7,495

-


- morbidity loss (t)

88,198

71,202

-

Animal traction loss (ha)

488,000

21,306

13

Manure loss (t)

701

66

0

Treatment

8,114

5

Acaricide application

3,008

20

Research and extension

6,550

4

Total loss, US$

168,402

100

ECF loss per cattle head

US$ 7.00


ECF loss per ha

US$ 1.10


Source: Mukhebi et al I (1992).

Sparse and insufficient data exist on how ECF affects livestock production. Therefore there is a need to improve estimates by conducting a survey of economic losses country by country taking into account differences in cattle types and production circumstances.

Limitations of current methods of ECF control

Although ECF is currently managed by the control of the vector ticks with acaricides and the use of drugs to treat infections, the widespread application of these methods in Africa has limitations. As discussed above, governments incur huge expenses in the provision of curative and tick control services.

In recent times, government budgets in most of the affected African countries have shrunk and the scarcity of foreign exchange for imports has grown more acute. As the competition for limited government resources has heightened from other pressing national development needs, the quantity and quality of animal health services and infrastructure has declined considerably (Haan and Nissen, 1985). The ability of govern meets to maintain dipping infrastructure, provide effective animal health extension service and import drugs and acaricides has been undermined.

The consequences of the control of ECF by currently available methods are therefore grim; extension staff generally do not have transport, most public dips are poorly managed and nonfunctional, the few operational ones are often dilute in acaricides concentration, drugs are not readily available to government veterinarians, and if they are available in local markets, they are too expensive for most smallholder farmers.

Other considerations which have rendered acaricide application a less reliable method include shortages of water for public dips, the development of resistance to acaricide by tick populations, uncontrolled cattle movements, civil unrest, contamination of the environment or food with toxic residues of acaricides and the existence of alternative hosts for ticks (mainly wild ungulates) in proximity to cattle (Young et al, 1988; Dolan, 1989).

Even when drugs for chemotherapy are readily available, their successful application requires diagnosis of the disease at its early stage of development. This specialisation is beyond the capacity of many smallholder farmers because of the poor state of the animal health service infrastructure. This factor, coupled with the high cost of drugs, implies that only a small proportion of animals which become infected with the disease receive treatment.

There is evidence that production losses due to tick infestation per se are too small to justify intensive acaricide application on economic grounds in zebu and Sanga cattle (Norval et al, 1988; Pegram et al, 1989). Furthermore, the existence of endemic stability in some areas implies that control can be selective, strategic and focused only on susceptible target cattle populations (Perry et al, 1990).

New methods of ECF control

The limitations associated with the current methods of ECF control and the opportunities for reducing reliance on intensive acaricide use in the region have prompted the search for new, safer, cheaper and more sustainable control strategies through immunisation.

At present, the only practical method of immunisation is by the infection and treatment method (Radley, 1981). This involves the inoculation of cattle with a previously characterised and potentially lethal dose of sporozoites of T. parva and simultaneous treatment with antibiotics. This confers life- long immunity to the animal.

The method has been shown to be technically efficacious in field trials carried out in different countries of the region (e.g. Robson et al, 1977; Morzaria et al, 1985; Musisi et al, 1989; Mutugi et al, 1989).

Immunisation through the infection and treatment method has been estimated to cost US$ 1.50-US$ 20.00 (Radley, 1981; Kiltz, 1985; Mukhebi et al, 1990), US$ 0.01-US$ 0.90 being the cost of producing one dose of the vaccine and the balance being the cost of delivering the vaccine to the animal in the field. The output will vary among countries depending on their policies regarding the production or procurement, delivery and pricing of the vaccine. Some countries conduct pilot immunisation programmes to provide data for the planning and implementation of widespread application of the infection and treatment method.

Assessing the economics of the infection and treatment method

There are few studies on the economic analysis of the infection and treatment method. Mukhebi et al (1989) showed that immunisation of beef cattle under farm conditions was extremely profitable. It yielded a marginal rate of return of up to 562% and it allowed a reduction in acaricide use from a frequency of twice a week to once every three weeks and even to the mere use of prolonged release acaricide-impregnated ear tags.

Perry et al (1990) used a cost-effective analysis to assess alternative tick and tick-borne disease control strategies in communal lands of Zimbabwe. The alternative control strategies, some of which the Department of Veterinary Services had started implementing, e.g. strategic dipping, would make less intensive use of expensive acaricides and rely more on controlled immunisation and the phased development of natural immunity to tick-borne diseases. The investigation revealed that alternative strategies were more cost effective than the previous intensive acaricide use practice and would reduce (save) the cost of tick and tick-borne disease control by up to 68% from the estimated amount of US$ 9 million annually.

Mukhebi et al (1992) assessed, ex-ante, the economics of immunisation by the infection and treatment method in the eastern, central and southern African region affected by ECF. The analysis showed high potential economic returns, with a benefit-cost ratio in the range of 9 to 17 under various assumptions.

However, the costs of the method and the economics of its application will obviously vary in time and space in each country depending on the cattle type and prevailing level of disease risk, the effect of immunisation on livestock productivity as well as the existing structure of costs and prices.

Limitations of the infection and treatment method

The infection and treatment method of immunisation, however, has some technical limitations. It does not eliminate the need for acaricide application due to the potential existence of other tick-borne diseases, although it allows considerable relaxation of acaricide use. In addition, the use of live parasites in the vaccine poses some safety drawbacks for large-scale immunisation purposes This is compounded by uncertainty about the spectrum of different species, strains and antigenic types of theileria parasites in different areas, variation in the sensitivity of different parasite isolates to therapeutic drugs and the development of a potentially infective carrier state in immunised animals. Furthermore, the application of the infection and treatment vaccine requires a liquid nitrogen system for cold storage and transportation and during the pilot application stage, an extended monitoring period post-immunisation to detect and treat any breakthrough infections. Both these aspects currently constitute high cost items in the delivery of the vaccine.

Research at the International Laboratory for Research on Animal Diseases (ILRAD) based in Kenya is continuing to further improve the safety and effectiveness of the infection and treatment vaccine and to develop genetically engineered safer vaccines that will avoid most of these drawbacks. In addition, ILRAD's socio-economics programme is conducting studies in several countries in the region to assess the epidemiological, economic, social and environmental impact of the method. These studies are aimed at generating further information that will be useful for the planning and implementation of widespread application of the method.

Policy issues

The current methods of ECF control are clearly beset with numerous limitations and are evidently inadequate and unsustainable. Prospects for developing new, safer, cheaper and more effective methods based upon immunisation are very promising. However, before a change in control strategy is adopted, certain policy issues must also be addressed if the new control strategies are to be sustainable. The decision for such change in the control strategy is often political. Politicians and government policy makers will therefore need to be convinced of not only the technical and economic feasibility of immunisation but also of its social, institutional and environmental soundness.

Policy issues regarding the production, delivery and financing of immunisation by the infection and treatment method would have to be addressed. For instance, how the production and delivery will be organised. Critical attention must be given to resource issues: what facilities, equipment, materials and manpower will be needed; where, when and how will they be procured and maintained; what institutions (national, regional and international) will be involved; what infrastructure (e.g. markets and extension) will need to be provided; who will pay what cost; and what will be the role of the public and private sectors. The control of other tick-borne diseases, other infections and constraints that will confound the control of ECF also needs to be considered. These and other questions require careful analysis if the benefits of ECF control by immunisation are to be maximised and their potential deleterious effects minimised.

Differences in livestock production systems and animal disease control strategies mean that individual countries will need to assess their own policy options to determine approaches compatible with optimal and sustainable application of new control strategies.

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