dieldrin and Trypanosomiasis--African

During an outbreak of Rhodesian sleeping sickness in the Lambwe Valley in 1980 initial tsetse control measures consisted of applications of dieldrin to the periphery of the Ruma National Park. This activity had a marked effect on the prevalence of sleeping sickness. Concern about the use of dieldrin caused the cessation of this programme and justified an aerial spray programme using endosulfan. Although the Lambwe Valley did not appear to be a good candidate for aerial spray, the endosulfan had a marked effect on tsetse fly levels and on the prevalence of sleeping sickness. Sleeping sickness cases were detected in decreasing numbers for eight months following the endosulfan programme, but the subsequent five months yielded no cases of sleeping sickness in the area. Some flies persisted, however, and they had regained high levels in about a year. As the prevalence of sleeping sickness increased another aerial spray programme was initiated in 1983, using pyrethrum as insecticide. The pyrethrum aerial spray programme did not make significant reductions in the Glossina pallidipes population or in the prevalence of sleeping sickness. A subsequent ground control programme using insecticides (dieldrin and cypermethrin) and bush clearing, conducted primarily within the National Park, has subsequently limited the prevalence of sleeping sickness to low levels.

Topics: Aerosols; Animals; Chrysanthemum cinerariifolium; Dieldrin; Disease Outbreaks; Endosulfan; Humans; Insect Control; Insecticides; Kenya; Prevalence; Pyrethrins; Trypanosoma brucei brucei; Trypanosomiasis, African; Tsetse Flies

The main events in the spread of Rhodesian sleeping sickness around the eastern shores of Lake Victoria during the 1930s and 1940s are summarized and the history of the disease in the Lambwe Valley area of western Kenya is described since its appearance there in 1959. The area was very receptive to the introduction and dispersal of T. rhodesiense on account of a close association between human communities and their domestic livestock, a large tsetse (Glossina pallidipes) population, and game animals. The possible origins of the first Lambwe Valley disease focus and the epidemiological significance of the main elements of the Lambwe environment (man, tsetse, game animals) are discussed in relation to the consolidation and spread of the disease throughout the area.Between 1968 and 1971 there was a marked decline in the incidence of the disease, probably as a result of tsetse-control operations that included ground and aerial application of insecticides, bush clearance, and the efforts of the Kenya Game Department to enforce the by-laws of the Lambwe Valley Game Reserve. However, it is considered that the situation remains potentially dangerous, mainly because populations of tsetse are recovering from the effects of aerial spraying and because there is evidence that the tsetse habitats are encroaching on farming land.

Topics: Animals; Animals, Domestic; Cattle; Dieldrin; Disease Outbreaks; Disease Reservoirs; Disease Vectors; Geography; Humans; Insect Vectors; Kenya; Mammals; Population Control; Rural Population; Transients and Migrants; Trypanosoma; Trypanosoma brucei brucei; Trypanosomiasis, African; Tsetse Flies; Weather; Zimbabwe

Topics: Animals; Cattle; Dieldrin; Humans; Insect Control; Kenya; Trypanosomiasis, African; Trypanosomiasis, Bovine; Tsetse Flies