Detection of Trypanosoma brucei, T. congolense and T. vivax infections in cattle, sheep and goats using latex agglutination.

A monoclonal antibody-based latex agglutination test for detection of circulating trypanosome antigens in animal serum was evaluated for the ability to detect natural T. brucei, T. congolense and T. vivax infections in cattle, sheep and goats in Ghana. The test detected antigens in 180/422 (42.7%) of cattle, 27/131 (20.6%) of sheep and 14/79 (17.7%) of the goats. By comparison, the microplate-based antigen-ELISA gave similar results (P > 0.01), detecting trypanosome antigens in 41.7% of the cattle, 19.8% of the sheep and 17.7% of the goats. Trypanosomes were demonstrated in the blood of 30 (7.2%) cattle, 7 (5.3%) sheep and 3 (3.8%) goats using the buffy coat technique (BCT). Of these, 26 cattle (86.7%), 6 sheep (85.7%) and all 3 goats (100%) were antigenaemic. The most prevalent single infection in all 3 animal species involved T. vivax, and the most common mixed infection involved all 3 trypanosome species in cattle and sheep. There was no mixed infection in goats. Compared with the antigen-ELISA, the sensitivity of the latex agglutination test was 98.3% in cattle and 100% in both sheep and goats, whilst the specificity was 97.2% in cattle, 99% in sheep and 100% in goats. False positivity with the latex agglutination test was 3.9% in cattle and 3.7% in sheep. There were no false-positive reactions with the test in goats. The latex agglutination assay promises to be ideal for testing small numbers of animals under field conditions.