Antibodies against Leptospira biflexa serotypes patoc and são paulo in pigs: possible occurrence and importance for the intracutaneous test for leptospirosis.

Leptospirin for the diagnosis of leptospirosis by an intracutaneous test contains antigenic material from 5 pathogenic Leptospira serotypes (10). During experiments with rabbits and pigs, leptospirin was injected into 6 pigs which had been infected artificially with apathogenic Leptospira biflexa serotypes patoc and são paulo. Three out of the 6 pigs showed a positive leptospirin reaction (11). This interfering reaction in animals having been infected with apathogenic L. biflexa was the reason to investigate the occurrence of biflexa antibodies in pigs from different areas in Germany by the microscopic agglutination. None of the 854 pigs showed biflexa antibodies producing a 50% agglutination at a serum dilution of 1:100. If at all, pigs may become infected naturally by L. biflexa; this apparently seems to be a rare incident. An impairment of the diagnostic value of leptospirin by L. biflexa antibodies can be excluded.