Molecular Epidemiological Study of a Human Brucellosis Outbreak - Weihai City, Shandong Province, China, 2022

What is already known about this topic? Brucellosis, mainly caused by Brucella melitensis ( B. melitensis ), is regarded as a significant zoonotic disease in China. In Weihai, located at the eastern end of the Shandong Peninsula, brucellosis has been in a low epidemic phase for the past five years. What is added by this report? This was the initial report of a brucellosis outbreak in the last five years. Strains of B. melitensis bv. 3 from Weihai and other cities showed a close genetic relationship, suggesting a potential common ancestry. What are the implications for public health practice? Epidemiological investigations depend on standardized and effective molecular typing methods and analysis tools for public health laboratories to identify and trace outbreaks. Understanding the circulation patterns of livestock in free-range households in heavily affected areas is essential for controlling the spread of brucellosis.