Serodiagnosis of African sleeping sickness in vervet monkeys by detection of parasite antigens

Sera of vervet monkeys experimentally infected with T. b. rhodesiense were examined using a double antibody sandwich ELISA and Procyclic Agglutination Trypanosomiasis Test (PATT) for the presence of circulating trypanosomal antigens and anti-procyclic surface antibodies, respectively. Trypanosomal antigens were detected at 7 days post infection and remained at a detectable level thereafter during the infection. Antigens were not detected in sera prior to experimental infection or at 26 days after trypanocidal drug treatment. Although both the PATT and the sandwich ELISA results correlated with the infection status of the animals, the sandwich ELISA gave a better indication of the disease progression than the PATT, especially during trypanocidal drug therapy. The results illustrate the potential utility of the double antibody sandwich ELISA for diagnosis of African sleeping sickness.