Comparison of indirect fluorescent antibody test and the modified agglutination test for the detection of Toxoplasma gondii antibodies in stray dogs from Southern Brazil

The aim of the present study was to determine the prevalence of antibodies to Toxoplasma gondii by two serological techniques in sera of 364 stray dogs from Brazil by immunofluorescence antibody test (IFAT, cut off point 1:16) and to the modified agglutination test (MAT, cut-off points 1:25 and 1:50). A total of 175/364 (48.07%) sera were positive by IFAT, and 108/364 (29.67%) and 85/364 (23.35%) were positive by MAT with cutoff points 1:25 and 1:50, respectively were positive by MAT. Cohen's Kappa Coefficient between IFAT and MAT was 0.81 (excellent) and 0.66 (substantial) with cutoff points 1:25 and 1:50, respectively. Using IFAT as gold standard, MAT sensitivity and specificity were 78% and 99% for 1:25 and 61% and 99% for 1:50, respectively. The results document of the usefulness of MAT for serological diagnosis because it does not require species-specific conjugate.