The use of an antigen-detection ELISA for the diagnosis of trypanosome infections in N'dama cattle in Gambia

An antigen-detection enzyme-linked immunosorbent assay (Ag-ELISA) for the detection of circulating trypanosomal antigens was evaluated for use in the diagnosis of trypanosomiasis in N'dama cattle in Gambia. Initial evaluation was carried out in cattle kept in areas of low or high tsetse challenge. Overall, approximately 12% of samples were parasite, but 67% showed presence of circulating antigens. The overall apparent sensitivity of the Ag-ELISA was 75%. In a separate experiment, the effects of treatment of antigenaemic N'dama cattle on weight gain and packed cell volume (PCV) was determined in animals kept under low level natural tsetse challenge. No differences were found in PCVs between drug treated and untreated animals but there was a significant weight gain in the drug treated group. Comparison of the same parameters in cattle in which parasites were detected by buffy coat technique (BCT), cattle which were Ag-ELISA positive but BCT negative, and cattle which were Ag-ELISA negative and BCT negative revealed little differences in weight, but PCVs were significantly lower in animals with a patent parasitaemia. (author). 4 refs, 4 figs, 3 tabs