Detection of circulating trypanosomal antigens in Trypanosoma evansi-infected animals using a T. brucei group-specific monoclonal antibody.

An antigen-detection enzyme immunoassay based on a T. brucei group-specific monoclonal antibody was used for the detection of circulating antigens in several animal species experimentally infected with T. evansi stocks from Sudan, Indonesia, Thailand and South America. Circulating antigens were detected as early as 6 days after infection, and they persisted throughout the observation period of up to 60 days postinfection. In an analysis of sera from naturally infected water buffaloes from Thailand, the test identified all the animals with positive parasitological findings, and 3 additional cases that had not been diagnosed by parasitological techniques. In an analysis of sera from pigs on a farm in Thailand suspected of a T. evansi outbreak, the assay detected "antigenaemia" in 66.7% of the animals, with antigen titres ranging from 1:2 to 1.512.