The Testryp CATT (Card Agglutination Test for Trypanosomiasis): a field study on gambiense sleeping sickness in Liberia.

The inhabitants of three Liberian villages in a known gambiense sleeping sickness area with a low prevalence were examined comparatively with the haematocrit centrifugation technique (HCT), the miniature anion exchange centrifugation technique (m-AECT), the indirect fluorescent antibody test (IFAT) and the Testryp CATT (Card Agglutination Test for Trypanosomiasis). Among 418 persons examined was one individual from whom trypanosomes could be isolated with the HCT and m-AECT. This positive case and another 21 individuals had positive titres of 1:40 and more in the IFAT. The same number, but not the same individuals, showed positive reactions in the CATT in the 1:5 serum dilution. The 1:25 dilution of blood and serum was inferior to the corresponding 1:5 dilution and could therefore be omitted. The 'false positive' rate in the CATT was 5.0% in the serum, 10.1% in the blood, and 11.5% in blood or serum. The combination of HCT and m-AECT in the field did not achieve better results than the CATT or IFAT. Thus the CATT can be recommended as the preferable technique for screening of gambiense trypanosomiasis in the field.