Brucella abortus in wildlife on selected cattle farms in Alabama

Two studies of brucellosis in wildlife on farms where the brucellosis infection prevalence in cattle was known are reported. On a research farm, 233 feral animals of 22 mammalian species and 12 of seven avian species were trapped during three time periods. Sixty were studied before cattle were introduced, 128 were studied while 501 cattle infected with Brucella abortus were calving and aborting, and 60 specimens were collected 20 mo after the last infected cow calved. Selected tissues from 229 wild animals were cultured and sera from 138 were examined using the brucellosis card, standard tube agglutination (STA), 2-mercaptoethanol (2-ME) and rivanol (RIV) tests. Brucella abortus was not recovered from any animals sampled prior to cattle being introduced and all sera collected were negative. Brucella abortus was isolated from four opossums (Didelphis virginiana) and one raccoon (Procyon lotor) in the group of animals trapped during the calving period. Three serums were tested and had STA titers ranging from 1:100 to 1:200. Of 68 sera only one had antibodies. Brucella were not isolated from 59 animals trapped after the calving period and only one of 42 serums had antibodies. On regional cattle farms, 243 wild animals were trapped. Brucellae were not isolated from 223 animals which were cultured. No serums had significant titers. The data from this study suggest opossums and raccoons can be infected from cattle but are unlikely to maintain the infection.