A family cluster of Brucella abortus infections possibly due to contact with a sika deer in Northeast China

Brucellosis is one of the most common zoonotic diseases worldwide. Although deer are reportedly infected by Brucella spp., deer-associated brucellosis cases have been rare. In this study, two patients in Heilongjiang Province, Northeast China, were diagnosed with brucellosis. They have contacted a sick sika deer before onset which was bought from another province, but have no contact with other infection sources. Molecular genotyping indicated that both were infected with Brucella abortus. This might be the first human cases caused by deer-associated B. abortus strains despite the frequent reports of B. abortus in deer. The role of deer in the transmission of B. abortus should be taken into consideration.