Abstract
Brucella canis (B. canis) causes a zoonotic infection of dogs. It is primarily transmitted to humans via exposure to reproductive fluids, particularly from parturition and abortions. Human infections are rarely reported world-wide but could pose a serious risk for vulnerable individuals. Historically, UK B. canis cases have only been reported in imported dogs. In June 2020, a canine infected with B. canis was reported to Public Health England and an Incident Management Team convened. We aim to describe the outbreak and implications for the public health risk assessment. Self-reported information from the index and linked households, microchip database searches and site visits were used to identify humans and dogs potentially exposed to B. canis and assess ongoing risks. Humans and dogs were tested for B. canis serologically and cultures were performed on tissue samples from two dogs. Dogs were categorised as positive, non-infected or suspected for B. canis according to the long-term management plan. Nine households were potentially exposed to B. canis. There were nine canine abortions or stillbirths in the households in the preceding 18 months. Three humans had a single positive Rapid Slide Agglutination (RSA) test at 6 weeks, but negative results for subsequent samples. The positive results were determined to be of uncertain significance. Thethree patients were asymptomatic and did not receive treatment. 75% (27/36) of dogs tested were seropositive and both cultures grew B. canis. All seropositive dogs originated from the index household. Puppies born to seropositive parents were sold to a further six households and are being followed up. This outbreak of B. canis identified the first documented transmission of B. canis between dogs in the UK. Despite highrisk exposures over a prolonged period no humans developed symptoms of brucellosis during the investigation. Increased awareness is needed among dog owners, veterinarians and health professionals about the risks and prevention of transmission of B. canis.
