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In Insect Transgenesis (Handler, A. and James, A., eds), pp. 271–287, CRC Press 48 Vreysen, M.J. et al. (2000) Glossina austeni (Diptera: Glossinidae) eradicated on the Island of Unguga, Zanzibar, using the sterile insect technique. J. Econ. Entomol. 93, 123–135 49 Shahid, M.A. and Curtis, C.F. (1987) Radiation sterilization and cytoplasmic incompatibility in a “tropicalized” strain of the Culex pipiens complex (Diptera: Culicidae). J. Med. Entomol. 24, 273–274 TRENDS in Parasitology Vol.17 No.1 January 2001 http://parasites.trends.com 1471-4922/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S1471-4922(00)01852-4 35 Review Historically, African animal trypanosomosis (AAT) has profoundly affected settlement and economic development in much of the African continent, and remains a major constraint to increased livestock production 1 . Moreover, tsetse infestations, by transmitting AAT, prevent the successful integration of crop and ruminant production 2 . Apart from the impact of the disease itself, it is argued that the mere presence of tsetse alters the distribution of susceptible livestock over vast areas and thus influences the type and number of animals kept, as well as the use of oxen for draught power, manure as crop fertilizer, and crop-residues and by-products as cattle feed 1,3 . Geographical information systems (GIS) are problem-solving tools that allow users to process and analyse spatial data layers in a multidisciplinary context. A GIS should thus be ideal for display, analysis and interpretation of the various factors affecting the epidemiology of AAT and its impact on people and their agriculture including: (1) the spatial patterns in tsetse challenge; (2) trypanosomosis risk; (3) clinical disease; (4) livestock biomass; (5) breed distribution; (6) farming systems; and (7) land use. GIS-related research activities discussed here can be divided into two groups: first, the development of improved methods to build reliable individual data layers; and second, the multilayer spatial analysis needed for improved decision making. The use of geographical information systems (GIS) in the management of African animal trypanosomosis in sub-Saharan Africa offers potential in assisting decisions on allocation of resources, prioritization of control areas, and planning and management of field operations. Here, Guy Hendrickx and colleagues review approaches being used to develop reliable data-layers and to incorporate these data into GIS models. They argue that techniques should be further refined to produce more-detailed data layers and to include a dynamic element, a problem rarely addressed until now. Spatial trypanosomosis management: from data-layers to decision making Guy Hendrickx, Stéphane de La Rocque, Robin Reid and Willy Wint