Potential for transmission of zoonotic helminth infections among dingoes and dogs in the Wet Tropics of North Queensland, Australia

Wild dogs (dingoes, free-ranging domestic dogs and hybrids) have the potential to pose a threat to biodiversity conservation and the health of domestic animals, livestock and humans in the Wet Tropics bioregion of north Queensland. The increasing human population in the Wet Tropics will inevitably result in more frequent interactions between people and wild dogs. One potential interaction is the transmission or 'spillover' of diseases, including zoonotic parasites, from dingoes to the area's native fauna, livestock, domestic animals, human residents and visitors. Investigating all potential hosts and their interactions is hence necessary to understand and mitigate the possibility of 'spill-over' or 'spill-back' of zoonotic infection. Indigenous communities are at particular risk due to limited management of domestic dog health and the ability of community dogs to roam free, possibly contacting dingoes and their habitat and resources. Dogs remain an integral part of Indigenous community culture and the health and treatment of dogs is intrinsically linked to community health and well-being. Research was undertaken in and around rural and remote Indigenous communities to understand the disease status of dingoes and sympatric community dogs. Using various parasitological techniques, combined with radio telemetry to track the movements of dingoes and free-roaming domestic dogs, risks of transmission of infection from dingoes to dogs and then people in Indigenous communities, or vice versa, were examined. Faecal samples collected from tracked dingoes revealed 100% infection with the zoonotic hookworm Ancylostoma caninum, and one animal was infected with Ancylostoma ceylanicum; this is the first report of this parasite in dingoes. A similar result was found for necropsied dingoes; however, a much more elevated infection rate was seen in dingo scats. Those scats positively sequenced for hookworm, contained A. ceylanicum, A. caninum and A. braziliense, with A. ceylanicum the dominant species in Mount Windsor National Park, with a prevalence of 100%, but decreasing to 68% and 30.8% in scats collected from northern and southern rural suburbs of Cairns, respectively. I also observed, for the first time, the presence of A. ceylanicum infection in domestic dogs (21.7%) and soil (55.6%) in an Indigenous community and found it was present in soil samples from two out of the three popular tourist locations sampled. Due to the ability of A. ceylanicum to cause a patent infection in humans, the zoonotic risk arising from this wild dog reservoir to communities in the Wet Tropics is of concern. Domestic dogs also had a high prevalence of A. caninum with 100%, 96.4%, and 88.0% infection of tracked dogs, necropsied dogs and dog scats, respectively, but A. ceylanicum was not found. Similar levels of infection of the zoonotic roundworm Toxocara canis were found in dingoes and domestic dogs. However, whipworm Trichuris vulpis infection was far more prevalent in domestic dog necropsies (78.6%) than in dingo necropsies (3.7%). Dirofilaria immitis infection was found in high prevalence with 71% infection seen in dingoes in low density housing areas. This result highlights the importance of dingoes as reservoir hosts of heartworm disease and that the subsequent risk of infection to companion animals and humans depends on local factors such as housing density, possibly linked to chemotherapeutic heartworm control in domestic dogs and climate. Eleven dingoes and seven free-roaming domestic dogs were fitted with GPS collars and tracked over an extended period. Dingo home ranges almost completely overlapped those of the domestic dogs and dingoes spent a substantial amount of time in areas used by dogs. I found that dingoes and dogs appeared to avoid direct contact however this spatial overlap in resource use presents an opportunity for the indirect spill-over and spill-back of zoonotic parasites, facilitated by the parasite's ability to survive for longer periods in the Wet Tropic's warm and humid conditions. Tracking and camera trap deployment in the Yarrabah community showed that the community rubbish tip and animal carcasses provided concentrated anthropogenic food sources for dogs and dingoes, and transmission risk is elevated in these locations. Two dog health days were conducted in the Yarrabah Aboriginal community to provide free veterinary consultation for pets, provide community members with information about new dog laws and registration and to provide information about parasites infecting dogs and the possible public health risks associated with them. This resulted in the provision of treatment and veterinary consultation to 134 dogs and one cat along with the development of guidelines for domestic animal management which I prepared and presented to Yarrabah Council to assist in the introduction of registration of pets. By using a "One Health" approach that integrated the disciplines of veterinary parasitology, epidemiology and ecological analysis of canids' home range and resource use, I was able to establish the prevalence of parasitic pathogens and the current status of infection in dingoes and determine the pathways and mechanisms which lead to the potential risk of transmission of infections among dingoes, wildlife, domestic animals and humans. I determined that hot spots of infection transmission are likely to be sources of anthropogenic-derived food such as the rubbish tip, animal carcasses and public congregational areas such as school sporting grounds. Similar risks are likely to occur in other Indigenous communities in the Wet Tropics and warrant investigation and intervention. Through collaboration with local, experienced environmental health workers I was able to achieve the overall aim of this project which was to determine, and provide workable and sustainable animal and health management practices to reduce the risk of spill-over of parasitic infection from dingoes to domestic dogs (or vice-versa). Mitigation measures should include exclusion fencing of the rubbish tip, effective disposal of animal carcasses, public education to increase community awareness about local zoonotic diseases and their prevention, along with regular chemoprophylactic therapy of community dogs and improved management of dogs and their diseases in Indigenous communities