[The use of nonpathogenic leptospira as diagnostic antigens for the diagnosis of leptospira infections in cattle].

The seroprevalence of leptospira antibodies was determined in 4377 bovine sera by microagglutination assay using 11 Leptospira interrogans serovars. In 10% (439 samples) of the sera, a positive reaction was detected. These included 275 sera (62.6%) with reaction to L. grippotyphosa, 159 (36.2%) to L. saxkoebing and 5 (1.1%) sera with reactions to other serovars. Multiple reactions were found in 9.8% of the 439 positive sera, whereby the Sejroe group dominated (65%) within the possible combinations of crossreactions. To determine the suitability of nonpathogenic strains as polyvalent diagnostic antigens, two L. biflexa serovar patoc strains were compared with the above-mentioned 11 L. interrogans serovars in microagglutination testing of 1995 screen sera. The sensitivity of the test was found to be 0.3% and the specificity was 80.3%. Using the two L. patoc strains, all of the 415 positive field sera and 11 positive control sera yielded negative reactions. Based on these results, the use of L. biflexa serovar patoc cannot be recommended as polyvalent antigen in the diagnosis of bovine leptospirosis by microagglutination.