The geographical distribution and the biology of the different species of tsetse fly are closely connected with the vegetation. Any modification in the vegetation cover may therefore change, in one way or another, the dynamics of tsetse populations and, consequently, influence the transmission of trypanosamiasis. Irrigation and rural development programmes which often drastically change the natural vegetation of vast areas will therefore result in major changes in the incidence, epidemiology and epizootiology of trypanosomiasis.

Only very limited studies have been carried out on this important problem and it is very difficult, if not impossible, to make a review of this subject as the data available are very fragmentary and often relate to specific situations.

The main purpose of this article is not only to review the data and information available at present, but also to identify and stress our lack of knowledge and the need for further research.

The problems created by establishment of irrigation and rural development programmes, industrial scale plantations, irrigated cultivations, livestock rearing centres are highlighted without neglecting the sociological and medical aspects of population transfers connected with these development programmes.

The conclusions attempt to identify the research which should be carried out in the field and propose some recommendations drawing attention to both the health services and to those responsible for planning and establishing irrigation and rural development programmes.