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. Brucella is a group of bacteria that infect domestic and wild animals. Humans can become infected if they have contact with an infected animal. Brucella have been frequently detected in deer, but the species Brucella abortus has never been reported to be transmitted from deer to humans. In this study, we report two patients from one family that were infected with Brucella abortus. We found that both had been in contact with a sick sika deer with no other possible sources of infection. This may be the first report that Brucella abortus can be transmitted from deer to humans. People who come into contact with deer or other animals should be aware of this potential risk.