title: Mapping the benefit-cost ratios of interventions against bovine trypanosomosis in Eastern Africa.
abstract: This study builds upon earlier work mapping the potential benefits from bovine trypanosomosis control and analysing the costs of different approaches. Updated costs were derived for five intervention techniques: trypanocides, targets, insecticide-treated cattle, aerial spraying and the release of sterile males. Two strategies were considered: continuous control and elimination. For mapping the costs, cattle densities, environmental constraints, and the presence of savannah or riverine tsetse species were taken into account. These were combined with maps of potential benefits to produce maps of benefit-cost ratios. The results illustrate a diverse picture, and they clearly indicate that no single technique or strategy is universally profitable. For control using trypanocide prophylaxis, returns are modest, even without accounting for the risk of drug resistance but, in areas of low cattle densities, this is the only approach that yields a positive return. Where cattle densities are sufficient to support it, the use of insecticide-treated cattle stands out as the most consistently profitable technique, widely achieving benefit-cost ratios above 5. In parts of the high-potential areas such as the mixed farming, high-oxen-use zones of western Ethiopia, the fertile crescent north of Lake Victoria and the dairy production areas in western and central Kenya, all tsetse control strategies achieve benefit-cost ratios from 2 to over 15, and for elimination strategies, ratios from 5 to over 20. By contrast, in some areas, notably where cattle densities are below 20per km(2), the costs of interventions against tsetse match or even outweigh the benefits, especially for control scenarios using aerial spraying or the deployment of targets where both savannah and riverine flies are present. If the burden of human African trypanosomosis were factored in, the benefit-cost ratios of some of the low-return areas would be considerably increased. Comparatively, elimination strategies give rise to higher benefit-cost ratios than do those for continuous control. However, the costs calculated for elimination assume problem-free, large scale operations, and they rest on the outputs of entomological models that are difficult to validate in the field. Experience indicates that the conditions underlying successful and sustained elimination campaigns are seldom met. By choosing the most appropriate thresholds for benefit-cost ratios, decision-makers and planners can use the maps to define strategies, assist in prioritising areas for intervention, and help choose among intervention techniques and approaches. The methodology would have wider applicability in analysing other disease constraints with a strong spatial component.
authors.affiliation: Division of Pathway Medicine and Centre for Infectious Diseases, School of Biomedical Sciences, College of Medicine and Veterinary Medicine, The University of Edinburgh, Chancellor's Building, 49, Little France Crescent, Edinburgh, EH16 4SB and AP Consultants, 22, Walworth Enterprise Centre, Duke Close, Andover, SP10 5AP, United Kingdom. Electronic address: alex@apconsultants.co.uk.
authors.forename: A P M
authors.initials: AP
authors.lastname: Shaw
authors.affiliation: Environmental Research Group Oxford (ERGO), Department of Zoology, South Parks Road, Oxford, OX1 3PS, United Kingdom.
authors.forename: G R W
authors.initials: GR
authors.lastname: Wint
authors.affiliation: Food and Agriculture Organization of the United Nations (FAO), Sub-regional Office for Eastern Africa, CMC Road, P.O. Box 5536, Addis Ababa, Ethiopia(1).
authors.forename: G
authors.initials: G
authors.lastname: Cecchi
authors.affiliation: Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA and Warwick Medical School, The University of Warwick, Coventry, CV4 7AL, United Kingdom.
authors.forename: S J
authors.initials: SJ
authors.lastname: Torr
authors.affiliation: Food and Agriculture Organization of the United Nations (FAO), Animal Production and Health Division, Viale delle Terme di Caracalla, 00153 Rome, Italy(1).
authors.forename: R C
authors.initials: RC
authors.lastname: Mattioli
authors.affiliation: Livestock Systems and Environment, International Livestock Research Institute (ILRI), P.O. Box 30709, 00100 Nairobi, Kenya.
authors.forename: T P
authors.initials: TP
authors.lastname: Robinson
mesh_terms: D000351:Africa, Eastern; D000818:Animals; D000981:Antiprotozoal Agents / Q000008:administration & dosage / Q000191:economics*; D002417:Cattle; D003362:Cost-Benefit Analysis; D007300:Insect Control / Q000191:economics; D007306:Insecticides / Q000191:economics*; D010572:Pest Control, Biological / Q000191:economics*; D014354:Trypanosomiasis, Bovine / Q000188:drug therapy / Q000191:economics / Q000517:prevention & control*
chemical_list: D000981:Antiprotozoal Agents; D007306:Insecticides
keywords: African trypanosomosis; GIS; Tsetse; benefits; costs