CHANGING TRENDS IN THE EPIDEMIOLOGY OF HUMAN BRUCELLOSIS IN CALIFORNIA FROM 1973 TO 1992 - A SHIFT TOWARD FOODBORNE TRANSMISSION

From 1973 through 1992, 426 cases of human brucellosis were reported i n California, of which 98% were laboratory confirmed. Brucella meliten sis was identified in 185 cases (78.7% of the bacteriologically typed cases). Hispanics accounted for 81% of the cases from 1983 to 1992 com pared with 65% during the previous decade (P < .01). The population-ad justed average annual incidence was higher in Hispanics, especially in children and teenagers, compared with non-Hispanic whites and African Americans. Slaughterhouse cases decreased from 25% during 1973-1982 t o <3% during the following decade. Changes in case distribution were c haracterized by a decreasing incidence in the Central Valley and an in creasing incidence in the San Francisco Bay area and the southern Coas t Range. Hispanics were more likely to report being infected by consum ption of milk and cheese in Mexico during 1983-1992 than during the pr evious 10 years (relative risk, 1.45). Between 1973 and 1992, human br ucellosis in California evolved from an occupational to a foodborne il lness.