The impact of expanded brucellosis surveillance in beef cattle on human brucellosis in Korea: An interrupted time-series analysis

Background: Korean surveillance program for bovine brucellosis was improved by extending it to beef slaughterhouses and by pre-movement testing of bulls on May 2005 (Intervention 1). The bovine brucellosis surveillance program was further extended to beef cattle farms with more than 10 heads of cattle on June 2006 (Intervention 2). Methods: To quantify the temporal relationship between bovine and human brucellosis, a time-series analysis was conducted using Korean national notification data reported between January 2004 and December 2014. Results: Our findings indicate that while during the pre-intervention phase (January 2004 to March 2005) there was no significant temporal relationship between the incidences of bovine and human brucellosis, significant temporal relationships were observed after Intervention 1 (June 2005 to June 2006, no lag, β = 0.57, p = 0.04), and Intervention 2 (July 2006 to June 2007, 1-month lag, β = 0.65, p = 0.03). Furthermore, significant changes in incidence in human were observed after Intervention 1 (β = - 0.17 per 10 million-people, p = 0.03) and Intervention 2 (β = - 0.19 per 10 million-people, p = 0.04). Conclusions: These findings indicated the changes of a nationwide comprehensive surveillance programme targeting all cattle is required for effective reduction in the human population.