Abstract

Objectives: Brucellosis is one of the most common zoonoses worldwide. Most cases in the United States occur among travelers or immigrants from endemic regions, mostly Central America. In this study, we aimed at describing and comparing the epidemiology and clinical presentation of brucellosis in pediatric and adult patients at two large tertiary care centers in Houston, Texas.

Methods: We identified patients diagnosed as having brucellosis between January 2000 and December 2009 by searching electronic medical records and reviewing microbiology records for positive cultures. Cases were defined as those with a positive blood culture for Brucella sp, a serum agglutination titer ≥1:80 (or both positive blood culture and serum agglutination titer ≥1:80), along with an epidemiologic risk factor and clinical presentation that is consistent with brucellosis.

Results: Six adult and 12 pediatric cases were identified; 13 of 18 (72%) cases were immigrants, mostly from Central America. The median ages for adult and pediatric patients were 53 and 3 years old, respectively. Ingestion of unpasteurized milk products was frequently reported. Common clinical features included fever (83%), arthralgias or arthritis (67%), and hepatosplenomegaly (61%). Positive blood cultures were more frequently reported among children than adults (83% vs 33%, P = 0.03). The most common laboratory finding was mildly elevated transaminases. Three adults (50%) but no children developed thrombocytopenia (P = 0.02). Relapsed infection was a frequent occurrence.

Conclusions: In the southern United States, brucellosis is an important consideration in the differential diagnosis of immigrants presenting with undifferentiated fever and joint complaints. A careful history often reveals an epidemiologic risk factor such as ingestion of unpasteurized dairy products.