Which Brucella species is least virulent to humans?

Brucella canis is considered the least virulent species in relation to human infections. It primarily affects dogs and can occasionally transmit to humans, but the incidence and severity of disease caused by B. canis are significantly lower compared to other Brucella species such as B. melitensis, B. abortus, and B. suis.

B. melitensis is known for causing the majority of human cases globally and is highly virulent; B. abortus is associated with cattle and also poses a significant risk to humans; likewise, B. suis can lead to severe infections in humans and is particularly virulent.

In contrast, while B. canis infections in humans can occur, they typically result in milder clinical manifestations and a lower risk of severe complications. Thus, B. canis stands out as having lower virulence when evaluating the risk of infection and severity of disease in humans. This understanding is vital for both clinical management and preventive measures in the context of zoonotic diseases like brucellosis.