Tsetse and trypanosomiasis in the Lambwe Valley, Kenya

The Lambwe Valley is shared between wild animals in a national park and adjacent human settlements with domestic livestock. Thicket and woodland in the valley are heavily infested with Glossina pallidipes. Rhodesian sleeping sickness continues to be a major human health hazard and livestock losses from nagana seriously affect the local economy. Epidemiology is characterized by periods of quiescence and flare-up, reflecting intermittent vector control measures to reduce transmission. The situation has been aggravated in recent years by extension of tsetse habitat and encroachment of settlements to the park. In 1981, an attempt at tsetse eradication by insecticidal methods was unsuccessful, due to technical difficulties and for reasons to do with the resilience of a large, entrenched tsetse population living under environmental optimal conditions. The options for dealing with the disease are outlined, and some of the critical assessments which have to be made are elaborated upon.