Epidemiology of Brucellosis in California, 1993-2017: A Continuing Foodborne Disease Risk for Older Latinos

Abstract

Background: Brucellosis is a severe occupational or foodborne zoonosis throughout much of the world. Although eradicated from domestic cattle in the United States, brucellosis remains a disease risk to people through acquisition and consumption of animal products from endemic countries.

Methods: Cases of human brucellosis reported through the California public health disease surveillance network were reviewed for 1993 to 2017.

Results: From 1993 to 2017, 492 cases of brucellosis were reported in California residents. Persons aged >65 years represented less than 20% of cases, but incidence in this age group (0.94 cases per 1 000 000 population per year) was more than twice the incidence in persons aged <19 years (0.44). Incidence was 10 to 20 times greater among Latinos compared with non-Latinos across all age groups and both sexes. Brucella melitensis was identified in 80% of patients for whom cultured Brucella were identified to the species level. Of 187 case patients who reported consuming specifically unpasteurized dairy products, more than 90% reported acquiring these products from outside of the United States, most commonly from Mexico. In the latter half of the study period (2006-2017), 73% of Latino case patients who reported consuming dairy products mentioned specifically Mexican-style soft cheese (queso fresco).

Conclusions: This study underscores the continuing serious health threat of brucellosis for Latinos in California, particularly older men, and the need for targeted public health messaging on preventing the risk presented by importation and consumption of unpasteurized dairy products from outside of the United States, principally Mexico.

Keywords: Brucella; brucellosis; foodborne illness; milk products; unpasteurized.