Immunization against Brucella infection. 7. Immunological and epidemiological studies in Cordoba, Spain.

The author describes a study, carried out in the Province of Córdoba, Spain, to test the efficacy of a live vaccine prepared from the Rev I strain of Brucella melitensis against caprine brucellosis and to determine the extent of natural infection in goats and humans in the Province.It was found that the vaccine significantly increased the resistance of the goats to infection without inducing a carrier state of the vaccine strain and that the immunity persisted for at least 15 months-the period of test.Serum agglutination tests, milk ring tests, and milk culture tests on goats showed that approximately 16-29% of the individual animals examined would be considered infective on the basis of one or other of the tests. Of the 118 herds tested, 111 were discovered to be harbouring infected animals.Serum agglutination tests on humans revealed that 25 of the 880 people tested (2.8%) had titres of 160 International Units (IU) or above and that, on the basis of a diagnostic titre of 80 IU or above, 7% of the population would be regarded as showing evidence of a past or present infection.