Epidemiological studies on the animal reservoir of gambiense sleeping sickness. Part II. Parasitological and immunodiagnostic examination of the human population.

The prevalence of the disease was determined in the population (n = 3402) of a highly endemic sleeping sickness area in the Ivory Coast and an area of recent low endemicity in southwestern Upper Volta by using parasitological techniques supplemented by the determination of trypanosome specific antibodies and serum macroglobulins (IgM). 62 cases of trypanosomiasis were diagnosed parasitologically in the sleeping sickness focus in the Ivory Coast. 30 Trypanozoon stocks were established for their behavioural and biochemical characterization. The percentage of specific antibody carriers. 26% and 10% obtained with the enzyme-linked immunosorbent assay (ELISA) in both areas, respectively, was compared to that obtained for raised IgM levels. False negative diagnosis resulted in 24% with the ELISA, 12% with the indirect immunofluorescent test (IFT) and 19% with the radial immunodiffusion (RID). Considering IFT and IgM levels together, the proportion of false negative results fell to 8%. Possible reasons for low sensitivities, especially of the ELISA are discussed.