Evaluation of Card Agglutination Test for T.evansi in Experimentally Infected Rabbits

Abstract

Improved diagnostic techniques for T. evansi are needed for diagnosis of cases and evaluation of chemotherapeutic efficacy of drug. This study was planned to evaluatethe Card Agglutination Test for Trypanosomosis (CATT) particularly developed for T.evansito correlate antibody to parasite detection in experimentally infected animals. Eight locally bred rabbits werepurchased from home-raised flocks. Six rabbits were inoculated on day 16 from purchase, by Trypanosome evansi isolate inter peritoneal (I/P) and 2 rabbit were left uninoculated as control. A direct card agglutination testfor detection of anti-trypanosome antibodies in serum or plasma of infected animal was used, the antigen consists of cloned bloodstream formtrypanosomes of RoTat 1.2; a predominant variable antigen type (VAT) of T.evansi. The test was conducted in sera collected from eight different rabbits, taken during different stages of pre, post infection and after treatment. In pre infection stage all rabbits werenegative. Sera collected during infection stage were positive in majority of inoculated rabbits, negative in uninoculated rabbit. Sera collected for30 days after treatment showed variable results as some rabbits were positive for some time while others became negative. Parasites were not detected after treatment with Cymelarsan. Death due to trypanosomosisis usually a result of severe anaemia, In this study the PCV, Hb & body weight of the infected Rabbits were lower than that of the negative uninfected Rabbits. It was concluded that CATT is highly sensitive in antibody detection but the results should be carefully evaluated because antibodies can persist after treatment. The possible way is to consider the low PCV, Hb and antibody titre for evaluation of the infection situation.