Evaluation of an antigen detection-ELISA test for the diagnosis of trypanosomiasis in naturally infected cattle.

The sensitivity and the specificity of the antigen detection ELISA proposed by Nantulya and Lindqvist (1989) for the diagnosis of African Animal Trypanosomiasis have been assessed in naturally-occurring infections. 1633 cattle were sampled in trypanosomiasis endemic area and examined for trypanosomes by darkground/phase contrast buffy-coat method described by Murray et al. (1977) and for circulating antigen by ELISA. Fifty sera from Markoye, a tsetse free area in north of Burkina Faso, and 49 sera from Germany were also tested. In trypanosomiasis infested area, BCT detected 144 (8.8%) positive animals while Ag-ELISA revealed 65.8% of positive. Out of the 144 BCT-parasite-positive, Ag-ELISA enable to detect 75% of positive. The predominant trypanosomes identified by BCT was Trypanosoma vivax followed by T. congolense while Ag-ELISA indicated T. congolense followed by T. brucei. Ag-ELISA detected 76.5% out of the 51 T. congolense-BCT-positive and only 17% of all T. vivax BCT-positive. Cattle carring mixed infection involving two or three trypanosomes, particularly those with T. brucei and T. congolense are the most frequent. In tsetse free area, Ag-ELISA detected one positive cattle carring T. brucei and T. congolense and showed an apparent specificity of 98%. No serum from Germany was detected positive. This study suggests the joint use of Ag-ELISA and BCT for the diagnosis of trypanosomiasis particularly in epidemiological study in endemic area.