Import Risk Analysis - Biosecurity New Zealand

8. Canine Brucellosis (Brucella spp.)
8.1. HAZARD IDENTIFICATION
8.1.1. Aetiological agent
The Brucella genus is comprised of six classical species based on host preference (Greene &
Carmichael 2006). Brucella canis, B. abortus and B. suis are on the preliminary hazard list.
8.1.2. OIE List
Bovine (B. abortus) and porcine (B. suis) brucellosis are listed.
8.1.3. New Zealand’s status
B. canis, B. abortus and B. suis are listed as unwanted, notifiable organisms (Ministry of
Agriculture & Forestry 2008).
8.1.4. Epidemiology
B. canis is probably found throughout most of the world and has been reported from the
United States, Canada, Central and South America, some European and African countries,
China and Asia. Some island nations such as Australia and New Zealand have been able to
maintain freedom (The Center for Food Security & Public Health 2007).
B. canis has a natural host range that is limited to species of Canidae. It is zoonotic but
humans are rarely infected. Cats have been infected experimentally and may develop a
transient bacteraemia but are considered highly resistant to natural infection.
The dog is the natural reservoir host for B. canis. However, clinical signs are generally
restricted to intact dogs and bitches and there are minimal clinical signs associated with
infection in neutered animals, despite a persistent bacteraemia. Neutered dogs are rarely
febrile although they may have mild generalised lymphadenopathy. Reproductively intact
male dogs develop epididymal swelling and testicular atrophy. In bitches, chronic intracellular
infection may be re-activated during pregnancy. Intact bitches may show infertility, abortion,
or give birth to stillborn or weak pups. Chronic bacteraemia may lead to clinical illness
dependent on where embolic organisms localise. This may cause uveitis, meningitis or
discospondylitis (Greene & Carmichael 2006).
Dogs are also susceptible to infection with B. suis, B. abortus and B. melitensis from
contacting infected tissues and secretions of farm animals. However, dogs are not important in
20 • Import risk analysis: Cats, dogs and canine semen MAF Biosecurity New Zealand