Yersinia enterocolitica O:9 infections were reported in Auvergne in 1988 to
1989, while brucellosis due to Brucella abortus was almost eliminated. The
serologic cross-reactions between the two bacteria complicated the diagnos
is of brucellosis cases. In 1996, human cases of Yersinia enterocolitica O:
9 infection were detected, with a peak incidence of 12 cases. Veterinary su
rveillance could have predicted the emergence of this disease in humans.