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Fluorescent conjugates were prepared from the sera of calves immunized with four Vibrio fetus strains and one Vibrio bubulus strain. The fluorescent antibody technique (FAT) was then used to detect vibrio organisms in preputial fluid collected from 67 bulls belonging to a Canadian artificial insemination (AI) unit. The V. fetus conjugates reacted with both V. fetus var venerealis and V. fetus var intestinalis. V. fetus was found in 20 animals (29.9%), 13 of which also harboured V. bubulus. In two cases, the FAT failed to detect V. fetus which was isolated by concurrent bacteriological examinations. It was concluded that the FAT can be a rapid method of detecting some carrier bulls but more reliable results are obtained when a combination of FAT and bacteriological methods is employed. It was found that a single sample giving negative results is inconclusive and additional tests are required before making a final diagnosis. The FAT can also be used to differentiate V. fetus isolates from V. bubulus.

The results of a survey which included the testing of 21,275 blood samples collected at various slaughter houses are described.Sixty-three herds had a single reactor with a titre of 1:100 or higher to a tube or plate agglutination test. Investigations in forty-five of these herds failed to detect the presence of brucellosis in the remaining mature swine.The prompt slaughter of the reactors may have eliminated possible sources of infection.

Complement-fixation (CF) and tube agglutination (TA) tests for demonstration of Vibrio fetus antibodies were conducted on the sera of three groups of ten heifers. One group was vaccinated subcutaneously with a commercial V. fetus var venerealis bacterin and challenged intra-utero, at the external os cervicus one month later; the second was infected only and the third vaccinated only. The vaccinated cattle developed high CF serum titers, but no such increase was observed in animals infected only. A moderate increase in serum antibody titers was demonstrated by the TA test following either infection or vaccination; although titers observed were not higher than those observed in the sera of some apparently normal uninfected animals. The group receiving both vaccine and challenge was the only one in which significant serum antibody titers were demonstrable by the TA test. The sera of these animals also had significant titers in the CF tests. The CF and TA tests detected serum antibodies produced by the parenteral inoculation of V. fetus antigen. These two tests were of limited value in detecting serum antibodies from animals with genital V. fetus var venerealis infection, although the formation of local antibodies was demonstrable by the vaginal mucus agglutination test.