Validation of a polymerase chain reaction assay for monitoring the therapeutic efficacy of diminazene aceturate in trypanosome-infected sheep

The diagnostic performance of a polymerase chain reaction assay (PCR) for m onitoring the effectiveness of aceturate diminazene treatment was compared with those of an antibody-detection ELISA test and the buffy-coat technique using sheep experimentally infected with either savannah-type or forest-ty pe Trypanosama congolense or I: vivax. Within the period of infection, the PCR using specific savannah-type I congolense primers showed a significant higher diagnostic sensitivity (p < 0.05) than the buffy-coat technique. Bot h techniques gave closed results for detecting forest-type T. congolense or T. vivax infections. Following trypanocidal treatment, the PCR showed that specific product disappeared definitively 1 or 2 days later in animals in which a decrease of the antibody level and a significant improvement of the red packed cell volume were observed. The occurrence of relapse infection was detected by the PCR in one animal infected by T. vivax on day 19 post-t reatment and confirmed by the persistence and increasing antibody level whe reas the huffy-coat technique detected parasites 42 days later. Then, the P CR signals remained positive on several occasions while parasitaemia was de tected only two times. The application of PCR combined with the antibody detection appeared to pro vide a useful tool as compared to the buffy-coat technique for monitoring t he effectiveness of trypanocidal treatment. (C) 2001 Elsevier Science B.V. All rights reserved.