The influence of serum concentration on the sensitivity and specificity of the microscopic aglutination test, using the L. biflexa, Buenos Aires strain, as antigen for diagnosing swine leptospirosis

Abstract

The influence of serum concentration on the results of the microscopic agglutination test (MAT), using the L. biflexa strain Buenos Aires as antigen, was investigated in three experimental groups of swines.
The group "A" composed of nine animals was the control. The group "B" composed of ten animals had its water supply contaminated with the L. biflexa strain during the first three experimental days. The group "C" composed of ten animals was inoculated with a virulent strain of L. interrogans serovar pomona by the intraperitonial route. The blood collections were obtained on the experimental days 5th , 15th , 30th ,
39th and 51st . The serum dilutions tested were: 1:10; 1:20; 1:40; 1:80 and 1:100. The amounts of negative results in group "A" represented the specificity of the test and the amounts of positive results in group
"C" the sensitivity. The results showed that when the concentration of the serum increases there was also an increase in its sensitivity but there was a decrease in its specificity. The best results of both of these characteristics were 60% at the serum dilution of 1 :20