Sleeping sickness in the Lambwe Valley in 1978.

Even though tsetse control measures were discontinued in the Lambwe Valley in 1974 the prevalence of Rhodesian sleeping sickness remained at low levels. A survey conducted in 1978 verified a low prevalence of disease (0.1%). Thirty-four per cent of the individuals tested were positive for malaria with the highest prevalence (44%) in children aged 0-9 years. Thirteen of 1340 individuals (0.97%) tested and found negative for sleeping sickness in 1978 developed the disease by 1985. Fourteen individuals with moderate titres (2+) in the IFAT but who showed no evidence of disease were traced and found to be alive and well seven years later. Three of these patients still had positive titres but the others had converted to negative. Sera from four patients infected and treated in 1978 were also positive, but only one of five patients treated in 1977 reacted in the test. The CFT as described did not appear useful as a diagnostic test.