Rebecca J. Traub

Description:Tropical climates in remote Aboriginal and Torres Strait Islander communities in northern Australia are conducive to the transmission of canine helminths such as hookworms, as well as ectoparasites such as fleas and ticks. In addition to their veterinary importance, these parasites may present a zoonotic risk either directly, or as potential vectors for bacterial pathogens. These factors necessitate efficacious and effective antiparasitic treatment programs for community dogs. A cluster-randomised trial was performed on three islands in the Torres Strait to examine the short-term efficacy and medium-term effectiveness of three treatment programs. Treatments administered included oral oxibendazole/praziquantel (Paragard®) and oral afoxolaner (Nexgard®); topical moxidectin/imidacloprid (Advocate®) and imidacloprid/flumethrin collars (Seresto®); and off-label oral ivermectin (Bomectin®). Canine faecal samples were collected and examined for endoparasites by faecal flotation and real-time PCR at baseline, 7-11 days after treatment and 6 months later. The proportion of dogs positive for Ancylostoma caninum at baseline and negative at day 7-11 was 9% (95% CI 4.4-17.4) for dogs treated with oxibendazole, 56.4% (95% CI 41-70.7) for moxidectin, and 89.7% (95% CI 73.6-96.4) for ivermectin. Faecal flotation results showed a greater than 90% egg reduction in 29.2% (95% CI 19.9-40.5) of dogs treated with oxibendazole, 79.4% (95% CI 63.2-89.7) for moxidectin, and 95% (95% CI 76.4-99.1) for off-label ivermectin. Elimination of ectoparasite infestation was observed at day 7-11 in 69.9% (95% CI 56.7-80.1) of dogs treated with afoxolaner, 80% (95% CI 60.9-91.1) with imidacloprid/flumethrin collars, and 0% (95% CI 0-11.7) for off-label ivermectin. Mixed effects modelling revealed only treatment group to be significantly associated with outcome measures. Based on these study results, the poor efficacy of oxibendazole against A. caninum renders it inept for treatment, while ivermectin and moxidectin were suitable. Ivermectin was unsuitable for ectoparasite treatment due to its poor efficacy, while afoxolaner and imidacloprid/flumethrin collars appear suitable.

Description:Quantitative polymerase chain reaction (qPCR) is an increasingly recognized diagnostic tool for soil-transmitted helminths (STHs), overcoming limitations of microscopy. We compared qPCR with Kato-Katz (KK) and sodium nitrate flotation (SNF; specific gravities 1.2 and 1.3) in determining STH prevalence and infection intensity using samples from a community survey of 351 people in Dak Lak province, Vietnam. Established correlation formulas were used to convert qPCR cycle threshold values to eggs per gram to compare infection intensity. Sensitivity, specificity, and agreement between methods were also investigated. Hookworm was the predominant STH detected, with prevalences of 70.3% (95% CI: 63.6-76.9) by qPCR, 59.1% (95% CI: 46.3-72.4) by 1.2SNF, 56.5% (95% CI: 43.2-69.4) by 1.3SNF, and 47.8% (95% CI: 34.6-57.6) by KK. Detection of Ascaris lumbricoides and Trichuris trichiura was low across methods. Prevalences of zoonotic hookworm Ancylostoma ceylanicum and Strongyloides species by qPCR were 3.0% (95% CI: 1.3-6.4) and 17.3% (95% CI: 8.1-22.3), respectively. qPCR detected higher prevalence of moderate- (8.3% versus <2%) and heavy-intensity (9.4% versus 0%) infections than microscopy. The sensitivities of microscopy methods were 81.0% (1.2SNF), 75.8% (1.3SNF), and 67.4% (KK). Diagnostic agreement for hookworm was moderate between qPCR and KK and between qPCR and 1.3SNF, and it was good between qPCR and 1.2SNF. The superior performance of qPCR in detecting hookworm coupled with the capacity to differentiate hookworm species and detect Strongyloides spp. supports the role of qPCR to inform control strategies, particularly for zoonotic reservoirs and use of macrocyclic lactones.

Description:: The southern brown bandicoot (Isoodon obesulus obesulus) is a small, endangered, Australian, ground-dwelling marsupial. Apart from isolated necropsy reports, there has not been a systematic investigation into the health and causes of death for this species. Objective: To investigate and document the causes of death and the parasites of free-ranging populations of southern brown bandicoots in southern, central Victoria, Australia. Methods: Gross necropsy, histopathology and identification of ectoparasites and endoparasites were performed on 62 dead southern brown bandicoots opportunistically collected from July 2011 to January 2018. Molecular methods were used to detect and genetically characterise the presence of Toxoplasma gondii in select tissues. Results: The vast majority of animals died as a result of either motor vehicle trauma or predation (45/62). A further seven bandicoots died from varying causes with either diagnostic gross or microscopic evidence of pathology, and there were five ejected pouch young. The cause of death was undetermined in another five cases. Toxoplasma gondii was detected in one southern brown bandicoot, which demonstrated polymorphisms in the B1 and SAG3 genes. This is the first definitively documented case of T. gondii infection in this species in Victoria. All of the identified parasites have previously been reported in southern brown bandicoots, apart from a metastrongyloid lungworm, which is reported here for the first time. Conclusions: Motor vehicle trauma and predation are highlighted as causes of fatality that likely threaten these populations of southern brown bandicoots. Further investigation into the role that disease, particularly toxoplasmosis, may be playing in southern brown bandicoot population decline is recommended.

Description:Zoonotic canine parasites and the vector-borne diseases they may carry can cause high morbidity and mortality in dogs and people. Many remote Indigenous communities in northern Australia have numerous free-roaming dogs, tropical climates favouring parasite development, and limited access to veterinary care, which can promote high prevalence of zoonotic parasites. To successfully combat parasites, treatment programs are needed, which are effective in reducing parasite burden and prevalence as well as being cost-effective and feasible. We compared canine parasite treatments in a Torres Strait Islander community setting, including oxibendazole/praziquantel tablets (OXI), moxidectin/imidacloprid spot-on (MOX), off-label oral ivermectin (IVM), afoxolaner chews (AFO), and flumethrin/imidacloprid collars (FLU). Cost surveys estimated the total annual and per-dog cost of each program. Markov modelling determined the cost per dog free of infection for each program using a government payer perspective over six-month and four-year time horizons. The annual cost per dog treated was $54.53 for OXI, $95.44 for MOX, $22.85 for IVM, $219.79 for AFO and $133.95 for FLU. IVM was less costly and more effective than other treatments against hookworm. FLU dominated in ectoparasite treatment. Sensitivity analyses supported these results. This study contributes cost-effectiveness data to inform parasite treatment program policy with aims of significant reductions in zoonotic canine parasite prevalence and subsequent reductions in environmental contamination with infectious parasite stages.

Description:The diversity and prevalence of canine vector-borne pathogens (VBPs) in Bhutan have to date remained unexplored, whilst recent epidemiological surveys in other South Asian nations have found diseases caused by VBPs to be rife in local dog populations. Importantly, many of such VBPs can infect people as well, with a building body of evidence identifying potentially zoonotic rickettsial organisms infecting humans in Bhutan. Given the lack of data on canine pathogens in Bhutan we employed a suite of deep-sequencing metabarcoding methods using Oxford Nanopore Technologies' MinION™ device to holistically characterise the bacterial, apicomplexan and filarial worm blood-borne pathogens of dogs in the country's south. Of the 95 stray, owned and community dogs sampled 78% (95% CI = 69%-85%) were infected with at least one VBP. Pathogen species detected were highly diverse including the bacteria Mycoplasma haemocanis in 16% (95% CI: 10-24%), Ehrlichia canis in 4% (95% CI: 2-10%), Anaplasma platys in 2% (95% CI: 0.5-7%) of dogs as well as the zoonotic species Bartonella clarridgeiae in 1% (95% CI: 0.1-6%), a potentially novel Bartonella spp. and an Ehrlichia chaffeensis-like bacterium, both in 1% (95% CI: 0.1-6%) of dogs. The apicomplexan haemoparasites Hepatozoon canis in 62% (95% CI: 52-71%), Babesia gibsoni in 45% (95% CI: 36-55%) and Babesia vogeli in 3% (95% CI: 1-9%) of dogs were also detected. Finally, 5% (95% CI: 2-12%) of dogs were found to be infected with the filarioid Acanthocheilonema reconditum and 1% (95% CI: 0.1-6%) with zoonotic Dirofilaria sp. hongkongensis. One canine was found positive to the filarioid Setaria tundra, a species normally found infecting cervids. The elucidated diversity of VBP communities highlights the strength of assumption-free diagnostics, such as metabarcoding, in detecting rare, novel, and unexpected pathogens. This approach to identifying pathogen diversity is of critical importance when investigating regions and populations that have thus far been neglected, with the findings aiding the development of future One Health informed strategies for disease control.