[Bovine brucellosis caused by Brucella melitensis in France]

Each Brucella species is known to have a definite host preference. In this respect, brucellosis in cattle is primarily due to B. abortus. As part of an investigation of the species and biovars responsible for bovine brucellosis in France, 312 strains have been examined since 1978 by the methods recommended by the Subcommittee on the Taxonomy of the genus Brucella. Of these, 264 (85%) were indeed classified as B. abortus members. However the 48 others (15%) had all the characteristics that define the species B. melitensis which usually affects small ruminants. Of these 48 strains, 43 (90%) came from the southern part of France in which B. melitensis infection in sheep and goats is enzootic and where the dissemination of this species by sheep flocks moving to mountain pastures most often accounted for cattle contamination. Evidence that B. melitensis infection in cattle traced to infected small ruminants was also strongly supported by biotyping. Of the 48 strains, 45 (94%) indeed were B. melitensis biovar 3 which is the most common in infected sheep and goats in France. B. melitensis infected cattle, which also constitutes a serious risk for public health, must therefore be considered by veterinary authorities because of epizootiologic implications in eradication and control programmes of sheep and goat brucellosis.