Brucellosis Surveillance - United States, 2010-2024.

Problem/Condition: Brucellosis is a zoonotic disease caused by bacteria of the Brucella genus, and humans can acquire the disease from infected animals or their by-products. This report on U.S. brucellosis cases is the first since the adoption of the 2010 Council of State and Territorial Epidemiologists' (CSTE) brucellosis case definition. Period Covered: 2010-2024. Description of System: Data from the National Notifiable Diseases Surveillance System (NNDSS), information from supplemental case report forms (CRFs), and data from analyses of clinical specimen testing by CDC during 2010-2024 were analyzed. The 2010 CSTE brucellosis case definition was used to determine case status using supplemental CRFs submitted for cases reported through NNDSS. Results: During 2010-2024, a total of 1,796 confirmed and probable cases of brucellosis were reported to CDC through NNDSS. A total of 878 of 1,796 (49%) cases also had a supplemental CRF submitted. Of these, 503 (57%) cases met the 2010 CSTE brucellosis confirmed or probable case definition on the basis of clinical and laboratory data submitted on the supplemental CRF; 383 cases (76%) were confirmed and 120 (24%) were probable. Among persons with brucellosis cases meeting the CSTE definition, 308 (61%) reported any travel, and of those, 245 (80%) reported only international travel during the 6 months before symptom onset. The most frequently reported exposures among persons with international travel were consumption of unpasteurized dairy products or undercooked meat (n = 195 [73%]). Among persons without international travel, the most frequently reported exposures were animal contact (n = 116 [62%]), particularly skinning and slaughtering wild animals (n = 47 [41%]) and hunting wild animals (n = 46 [40%]). Interpretation: The lack of adequate clinical or laboratory data led to the exclusion of nearly half of the supplemental CRFs from this analysis. However, the following recognized exposures to Brucella were identified in cases with adequate information: 1) consumption of unpasteurized dairy products or undercooked meat, particularly those produced outside the United States or meat from wild animals, and 2) animal contact, especially skinning and slaughtering of wild animals. Findings suggest ongoing public health messaging to reduce exposures from unpasteurized dairy products and undercooked meat, and to promote safe field dressing practices among hunters. For hunters and other persons who skin or slaughter wild animals, safe field dressing practices might help reduce infection risk. Public Health Action: Increasing brucellosis awareness among populations at risk for infection, health care providers, and public health officials will strengthen prevention and surveillance efforts and ultimately improve patient outcomes.