Immune trypanolysis test with blood spotted on filter paper for epidemiological surveillance of sleeping sickness.

Objectives: The immune trypanolysis test (TL) is an accurate sero-diagnostic tool increasingly implemented for sleeping sickness medical surveillance, but it is restricted to the reference laboratories. To facilitate storage and transport of the test specimen, we developed a protocol for the examination of blood spotted on filter paper (TL-fp) that can be stored and shipped at ambient temperature. We compared its performance with the classical TL on plasma (TL-pl) that needs to be kept frozen until use.

Methods: The study was conducted in active foci of the Republic of Guinea. In total, 438 specimens from treated and untreated sleeping sickness patients and serological suspects were tested with both methods.

Result: TL-fp gave significantly less positive results than TL-pl, but all the confirmed sleeping sickness cases were positive with the TL-fp protocol.

Conclusion: TL-fp appears to offer a good compromise between feasibility and sensitivity to detect currently infected subjects who play a role in the transmission of Trypanosoma brucei gambiense and is useful for contributing to the elimination of gambiense sleeping sickness.