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Sleeping sickness in the Lambwe Valley in 1978
B T Wellde1, D A Chumo, W T Hockmeyer
1Walter Reed Project, Veterinary Research Laboratory, Ministry of Agriculture and Livestock Development, Kabete, Kenya.
Annals of Tropical Medicine and Parasitology
|August 1, 1989
Summary
Rhodesian sleeping sickness prevalence remained low in Lambwe Valley after control measures ceased. A 1978 survey found low disease rates, with few individuals developing the illness by 1985.
Area of Science:
- Medical Entomology
- Tropical Medicine
- Epidemiology
Background:
- Tsetse control measures in Lambwe Valley were halted in 1974.
- Post-control surveillance is crucial for understanding disease dynamics.
Purpose of the Study:
- To assess the long-term prevalence of Rhodesian sleeping sickness after control cessation.
- To evaluate the incidence of disease in individuals previously found negative.
- To assess the utility of serological tests in disease monitoring.
Main Methods:
- A 1978 survey to determine disease prevalence.
- Longitudinal follow-up of individuals negative for sleeping sickness in 1978.
- Use of Indirect Fluorescent Antibody Test (IFAT) and Complement Fixation Test (CFT) for serological assessment.
Main Results:
- Rhodesian sleeping sickness prevalence was low (0.1%) in 1978.
- Only 0.97% of individuals negative in 1978 developed the disease by 1985.
- Individuals with moderate IFAT titres remained well, with some converting to negative.
- CFT showed limited diagnostic utility.
Conclusions:
- Rhodesian sleeping sickness remained at low endemic levels in Lambwe Valley post-control.
- Long-term follow-up indicates a low risk of disease development in seronegative individuals.
- IFAT shows potential for monitoring exposure, while CFT is less useful diagnostically.