EN
The diagnosis of brucellosis in pigs is based almost entirely on serological assays. None of the tests has been shown to be reliable in routine diagnosis in individual pigs. The biggest problem are false positive serological reactions (FPSRs) caused primarily by Yersinia enterocolitica O:9. The OPS component of the sLPS of Brucella is almost identical with that of Y. enterocolitica O:9. Thus no routinely used serological tests based on this antigen can distinguish between antibodies raised to these two infections. This paper presents the results of the examinations of 6 batches of pigs (total of 452 serum samples) traded between countries and causing major diagnostic problems. Positive reactions in RBT, SAT, CFT and I-ELISA were observed in all these batches of animals. Additionally 2 out of 21 samples from one of the batches were positive in 2-Me. FPSRs in the diagnosis of pigs for brucellosis seem to be a growing problem in international trade. The absence of provisions explicitly regulating the problem of FPSRs may have serious consequences, such as the slaughter of animals or even international repercussions. Clear guidelines for dealing with such cases should therefore be formulated.