Emergence of Brucella suis in dogs in New South Wales, Australia: clinical findings and implications for zoonotic transmission

Abstract

BackgroundAnimal reservoirs of brucellosis constitute an ongoing threat to human health globally, with foodborne, occupational and recreational exposures creating opportunities for transmission. In Australia and the United States, hunting of feral pigs has been identified as the principal risk factor for human brucellosis due to Brucella suis. Following increased reports of canine B. suis infection, we undertook a review of case notification data and veterinary records to address knowledge gaps about transmission, clinical presentation, and zoonotic risks arising from infected dogs.ResultsBetween 2011 and 2015, there was a 17-fold increase in the number of cases identified (74 in total) in New South Wales, Australia. Spatial distribution of cases largely overlapped with high feral pig densities in the north of the state. Ninety per cent of dogs had participated directly in pig hunting; feeding of raw feral pig meat and cohabitation with cases in the same household were other putative modes of transmission. Dogs with confirmed brucellosis presented with reproductive tract signs (33 %), back pain (13 %) or lameness (10 %); sub-clinical infection was also common (40 %). Opportunities for dog-to-human transmission in household and occupational environments were identified, highlighting potential public health risks associated with canine B. suis infection.ConclusionsBrucellosis due to B. suis is an emerging disease of dogs in Australia. Veterinarians should consider this diagnosis in any dog that presents with reproductive tract signs, back pain or lameness, particularly if the dog has a history of feral pig exposure. Moreover, all people in close contact with these dogs such as hunters, household contacts and veterinary personnel should take precautions to prevent zoonotic transmission.

Clinical management ofBrucella suisinfection in dogs and implications for public health

“…Brucellosis referable to Brucella suis is a notifiable disease in New South Wales (NSW) and has recently emerged in dogs in this state . Brucellosis ( B. suis ) occurs in dogs in Queensland (QLD) and likely elsewhere in Australia, although little is published in the veterinary literature.…”

Prevalence, risk factors, and geographical distribution of zoonotic pathogens carried by peri-urban wild dogs

“…However, the emergence of either ABLV or Hendra within the wild dog population would have substantial consequences and it reiterates the need for effective surveillance of emerging or potentially emerging diseases in wildlife populations. Pathogens such as Brucella suis were of significant interest due to the recent discovery of several pig-hunting dogs in NSW presenting with the disease (Mor et al, 2016). Although testing was performed for B. suis, the limited number of serum samples that were collected and sample quality significantly limited our ability to detect the pathogen within the wild dog populations.…”

“…Hunting dogs are likely to become infected through blood borne contact with infected swine, although ingestion of offal, tissue or foetal material is also a possible cause of infection. Between 2011 and 2015, there has been a 17 fold increase in the reporting of hunting dogs that have been diagnosed with B. suis biovar 1 infection in NSW (Mor et al, 2016).…”

“…Recently, trends in canine B. suis infection have been documented in association with feral pig hunting (Mor et al, 2016;Ramamoorthy et al, 2011). Hunting dogs are likely to become infected through blood borne contact with infected swine, although ingestion of offal, tissue or foetal material is also a possible cause of infection.…”

“…Hence, it is reasonable to suggest that the population of wild dogs may also be infected. The risk to humans residing in a household with an infected dog remains unknown (Woldemeskel, 2013), although plausible according to Mor et al (2016). Similarly, the public health impact from an infected wild dog in peri-urban regions is unknown.…”