A joint tsetse and trypanosomosis control program has been carried out along the Uganda-Kenya border since July 1991. A combination of tsetse trapping, pour-on and chemotherapy has been used. Different combinations of control strategies were tried in the project area divided into three zones (A, B and C). In zone A, large-scale applications of pour-on, tsetse trapping (8-10 traps/km2) and chemotherapy were used. In zone B, only tsetse trapping (8-10 traps/km2) and chemotherapy were used. In zone C, block treatment of cattle in the entire area with diminazene aceturate was carried out followed by less intensive tsetse trapping (4-5 traps/km2). During monitoring, 400 cattle in each zone were screened every three months and the tsetse apparent density determined every month. From July 1991 to March 1997 reductions in the prevalence of trypanosomosis and apparent tsetse density of 94 and 99.5% in zone A, 89 and 99.5% in zone B and 79 and 95% in zone C, respectively, were achieved and maintained. The predominant Trypanosoma species found
in cattle during the control period were: T. vivax in zone A, T. vivax and
T. congolense in zone B, and T. vivax, T. congolense and T. brucei in zone
C. Glossina fuscipes fuscipes was the only tsetse fly species caught. The most effective control strategy was an initial large-scale application of pour-on, followed by trapping and regular chemotherapy. However, control effectiveness seemed to be influenced by the level of trypanosome challenge, speed of initial reduction in tsetse density and sustainability of tsetse and trypanosomosis control inputs during the campaign.