Predicted tsetse distributions

The tsetse fly (genus Glossina) is found throughout the continent of Africa and is the primary vector of human and animal sleeping sickness. It is of substantial significance to human health and, through its impact on livestock, the economic welfare of rural farmers and stockowners. It is estimated that eradicating the disease would lead to as much as a threefold increase in cattle numbers within the afflicted areas (see PAATIS for more details) and to economic benefits of billions of dollars per year.

As a result, the distributions of the various tsetse species are of significant interest to those concerned with rural poverty in developing Africa. Reliable assessments would permit planned disease prevention programmes through the suppression or control of the disease vector.

Though substantial efforts have gone into mapping tsetse distributions, much of the currently available information dates back to the late sixties and early seventies. Limited resources have prevented any systematic updating for the continent as a whole, although a significant number of sub-national surveys have been carried out.

Much of the widely available data on tsetse are in the form of presence or absence maps, and provide little information on the fly abundance which is more closely allied to disease risk. Unfortunately, the extensive collection of fly abundance figures is well beyond existing resources.

Two solutions present themselves: either to extrapolate from comparatively few, and small area abundance surveys, or to use alternative measures of fly population levels. Whilst the first is inappropriate for continental level predictions, the second is made more feasible by estimating the probability of presence, rather than just presence or absence. It may be reasonable to assume that fly abundance is related to the probability of fly presence, although it will be necessary eventually to test this assumption by careful field studies.

This site is being constructed by the Environmental Research Group Oxford (ERGO) drawn from work carried out by ERGO and the TALA Research Group, Department of Zoology, Oxford University, funded by the Animal Health Programme of the UK's Department for International Development and the Animal Health Service (AGAH) of the Food and Agriculture Organisation of the United Nations (FAO). Further information can be obtained from the authors, William Wint and David Rogers.

Methods ] Distributions ]