[Brucella titers in subclinical infections due to Yersinia enterocolitica serotype O:9 in a pig-breeding farm (author's transl)].

According to the Federal German Veterinary Public Health Regulations part of the stock of a pig-breeding farm in Lower Franconia (South Germany) had to be destroyed due to the findings of positive serological titers against Brucella. B. suis was not isolated from various specimens examined by the local veterinary public health authorities, but the authors found Yersinia enterocolitica serotype O:9 in 15 of 117 pigs investigated (12.8%). The organisms were cultured from 6 out of 117 specimens of fecal material (5.1%), and from 10 out of 55 pharyngeal tonsils (18.2%). The examination of 45 mesenteric and 2 submandibular lymphnodes remained negative. In 9 out of 93 sera titers against B. abortus between 1:20 and 1:40 were detected in tube agglutination but not in complement fixation tests. These sera and an additional serum specimen gave simultaneous reactions against Y. enterocolitica serotype O:9 ranging from 1:40 to 1:640 (Table 2). By cross-absorption antibodies to Brucella were completely removed, but to Yersinia titers between 1:10 and 1:320 remained detectable in 7 sera. It may be concluded that the Brucella titers observed in the animals were caused by subclinical infections with Y. enterocolitica serotype O:9 which is known to give rise to marked serological cross-reactions with various Brucella antigens. The importance of the above findings will be discussed in view of the current veterinary public health regulations.