Researchers looking into how authorities might respond to a rabies outbreak in Australian dogs have found that on its own, the removal of dogs would not be an effective control strategy, according to a University of New England academic.
Dr Wendy Brown from the School of Environmental and Rural Science says Australia is currently free from rabies but an incursion from nearby Indonesia, where the virus is endemic, is a feasible threat.
“The study looked at how the disease would spread and how effective dog culling and vaccination strategies would be in Australia’s different dog populations. What the models highlighted is that killing dogs as a sole strategy doesn’t work. As demonstrated in other parts of the world, culling has the potential to create a vacuum where new dogs move into that space and bring the rabies virus with them. In the case of domestic pet dogs, when people have heard authorities are culling, they may hide or transport the dogs to another area, taking the disease with them, so it just doesn’t work,” Dr Brown said.
UNE PhD student Jessica Sparkes spent three years in the field tracking dog movements and their interactions as part of a joint UNE-NSW DPI-Invasive Animals CRC project. Computer-generated models using the field data collected were used to simulate rabies incursion scenarios within three dog populations, including free-roaming domestic dogs from a remote indigenous community in Australia’s north, and free-roaming domestic and wild dogs in north-east New South Wales.
“Through undertaking this research, we found that a blanket management approach to controlling a rabies outbreak would not work, because there are such distinct dog groups in Australia that would react very differently to an incursion,” according to Jessica Sparkes.
One scenario considered by the research team looked at an incursion via an Indonesian fishing boat into an indigenous community in the Tiwi Islands. Because 90% of the dog population in these communities are free roaming, the infectious intruder is able to transmit the rabies virus to community dogs quickly and easily.
The second scenario looked at an infected dog brought into the port of Ballina in north-east NSW, from Indonesia on a yacht. In this scenario, the virus is transmitted to local wild and domestic dogs through direct contact with the infective introduced dog, via an aggressive confrontation.
“We found that free-roaming domestic dogs residing in the remote indigenous community in northern Australia were at highest risk of contracting and spreading rabies. For that group, the disease spread rapidly through the population because dogs are free to roam, due largely to a lack of fencing for containment.
“In contrast, it appears that in the wild dog population in north-east NSW, rabies would spread more slowly, and may go undetected for some time. The consequence of this scenario is that rabies could become established by the time it is detected,” said Jessica Sparkes.
Dr Brown says their models suggest that 70% of the dog population would need to be vaccinated to effectively control an outbreak in Australia.
“This poses some challenges for dogs living in the wild. In wild dog populations a combination of culling and oral vaccination baits was considered the best strategy.”
Dr Brown recommends a consolidated research approach together with improved dog management, including de-sexing and vaccination campaigns targeted in high risk areas, such as free-roaming domestic dog populations in remote northern Australia. This should be partnered with education and dog health programs in the island communities north of Australia to help mitigate the spread of rabies before it reaches mainland Australia.
The paper Rabies disease dynamics in naïve dog populations in Australia, was published in the Preventative Veterinary Medicine Journal.