Screening for Trypanosoma brucei gambiense antibodies with the Indirect Fluorescent Antibody Test (IFAT). Effect of age and previous treatment.

This paper reports on some of the findings of a longitudinal multi-round investigation into the predictive power of early signs and symptoms of human African trypanosomiasis caused by T.b. gambiense, in the Rural Health Zone of Kasongo (Maniema, Zaire). It assesses the importance of the effect of age and a history of previously treated sleeping sickness on serological positivity as measured by the Indirect Fluorescent Antibody Test (IFAT), used as a screening test. The impact of including age and a history of previous sleeping sickness as part of the screening process is discussed in terms of sensitivity and positive predictive value. Including weak serological positivity among the screening criteria does not appear to improve the sensitivity of the IFAT test in this setting.