Abstract：On August 11, 2022, Tongxiang Center for Disease Control detected a case of brucellosis, and the case was not engaged in related work. Case finding and risk factor investigation were immediately conducted to trace the source of infection. It was revealed that the case sold aquatic products at a farmer's market and frequently picked up goods at a seafood warehouse adjacent to a lamb slaughtering site. There was a potential risk of infection due to indirect contact with slaughtered lambs or contaminants. Serological tests were conducted on 9 employees of the slaughtering site and 48 residents nearby, and the brucellosis cases diagnosed in hospitals in the same area were searched. A total of 11 brucellosis cases were identified, including 9 confirmed cases and 2 asymptomatic infections. There were 2 cases of slaughtering workers and 9 cases of non-occupational individuals from the surrounding area of the slaughtering site. Brucella melitensis biovar 3 were isolated from a slaughtering worker and a non-occupational individual. The slaughtered lambs primarily came from northern regions such as Inner Mongolia and Heilongjiang. It was concluded that it was a cluster caused by Brucella melitensis biovar 3 and spread through direct or indirect contact with imported infected lambs or contaminated environments from a lamb slaughtering site. It is suggested to strengthen the quarantine of imported sheep, legally shut down non-compliant lamb slaughtering sites, implement designated slaughtering and enhance occupational protection.
