The role of dogs in the transmission of Coxiella burnetii to humans is uncertain, and extensive seroprevalence studies of dogs have not been previously conducted in Australia. This study determined C. burnetii exposure in four diverse canine subpopulations by adapting, verifying and comparing an indirect immunofluoresence assay (IFA) and an enzyme-linked immunosorbent assay (ELISA) used to detect anti-C. burnetii antibodies in humans. Canine serum samples (n = 1223) were tested with IFA from four subpopulations [breeding establishments; household pets; free-roaming dogs in Aboriginal communities; shelter dogs]. The proportions of seropositive dogs were as follows: breeding (7/309, 2.3%), household pets (10/328, 3%), Aboriginal communities (21/321, 6.5%) and shelters (5/265, 1.9%). Dogs from Aboriginal communities were 2.8 times (CI 1.5-5.1; P < 0.001) more likely to be seropositive than dogs from other populations. The ELISA was used on 86 of 1223 sera tested with IFA, and a Cohen's Kappa coefficient of 0.60 (CI 0.43-0.78) indicated good agreement between the two assays. This study has established that Australian dogs within all four subpopulations have been exposed to C. burnetii and that a higher seroprevalence was observed amongst free-roaming dogs associated with Aboriginal communities. As C. burnetii recrudesces during pregnancy and birth products contain the highest concentration of organism, individuals assisting at the time of parturition, those handling pups shortly after birth as well as those residing in the vicinity of whelping dogs are potentially at risk of developing Q fever. However, the identification of active antigen shed in excreta from seropositive dogs is required in order to accurately define and quantify the public health risk.

The potential role of cats in transmitting Coxiella burnetii to humans was highlighted in a Q fever outbreak, linked to a caesarean section in a breeding queen, in an Australian small animal veterinary hospital. The objectives of this study were to evaluate the C burnetii seroreactivity of the breeding queen and other cats residing at the same breeding cattery (n = 27) and to evaluate C burnetii infection of the breeding queen by molecular and histological methods. Three assays [complement fixation test (CFT), indirect immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA)] were used for serological evaluation. Additionally, uterine and ovarian samples collected from the breeding queen 11 weeks post-parturition were assessed by routine and specialised histological methods and polymerase chain reaction. The breeding queen showed strong seropositivity using CFT (titre 1/32), IFA (titre phase I 1/8192 and phase II 1/8192) and ELISA; however, the reproductive tract showed no evidence of pathology or C burnetii infection. A number of cattery-confined cats were identified as seropositive to phase II and/or phase I C burnetii. Serological detection of C burnetii in a breeding cattery linked to a Q fever outbreak indicates likely infection by this bacterium in Australian feline populations, re-confirming the relevance of this zoonosis.

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The discovery of antibodies against Coxiella burnetii in cattery-confined breeding cats indicating prior or current exposure (Shapiro et al., 2015) prompted an investigation into possible sources of infection. One hypothesis was that raw meat diets containing reservoir species may provide a source of C. burnetii transmission. The aim of this pilot study was to determine whether C. burnetii DNA was present in raw meat sold exclusively for companion animal consumption. The sample population consisted of raw meat packages (n = 58) of primarily kangaroo origin, with three to four aliquots (50-120 mg) randomly selected from each package. Genomic DNA was extracted from whole tissue in each of these aliquots using a modified protocol.Three quantitative PCR assays were used for the detection of C. burnetii targeting the IS1111 gene, the heat shock operon htpAB and the C. burnetii outer membrane protein-coding gene, com1. Coxiella burnetii DNA was detected in 25/58 samples (43%) using the IS1111, htpAB and/or com1 PCR assays and confirmed by DNA sequencing.All samples amplifying a product in the com1 assay also amplified a product in the htpAB and IS1111 assays. A total of 17/58 (29%) packets were positive with all three genes, 4/58 (7%) were positive with two genes (IS1111 and htpAB) and 4/58 (7%) were positive with the IS1111 gene only. Coxiella burnetii DNA was five times more likely to be found in offal than skeletal muscle meat samples. All meat samples in which C. burnetii DNA was found were from kangaroo tissues, while samples labelled as non-kangaroo meat (n = 4) were negative. Multi-locus variable number of tandem repeat analysis (MLVA) identified three different genotypes of C. burnetii that have all been identified previously from Australian human clinical Q fever cases. Further investigations are required to determine the potential role of certain raw meats in the transmission of C. burnetii to cats and humans. K E Y W O R D Scats and dogs, Coxiella burnetii, kangaroo, pet food, Q fever, quantitative Polymerase Chain Reaction (qPCR), raw meat

BackgroundVector-borne diseases of dogs in Australian Aboriginal communities are relatively unexplored. These dogs represent a unique group with variable ecto- and endo-parasitic burdens, nutritional stresses and a general lack of veterinary intervention. We investigated haemoprotozoal and bacterial pathogen prevalences in relation to erythrocyte and platelet numbers in dogs from North-West New South Wales (N-W NSW) and the Northern Territory (NT; Central Australia).MethodsReal-time PCR (qPCR) amplification of Anaplasma platys, Babesia vogeli, Mycoplasma haemocanis, Candidatus Mycoplasma haematoparvum and Bartonella spp., serological screening for Coxiella burnetii, and Bartonella spp. and haematological analyses were performed on dogs from the two cohorts (96 dogs in total). Brucella suis serology was determined additionally for the N-W NSW cohort.Results Anaplasma platys (n = 26 dogs), Babesia vogeli (n = 7), Candidatus Mycoplasma haematoparvum (n = 10 dogs), and Mycoplasma haemocanis (n = 14) were detected in the sample population (n = 96) using qPCR. There were significant associations between (i) A. platys and anaemia (OR 8.7, CI 2.4–31.7; P < 0.001), thrombocytopenia (OR 12.1, CI 3.4–43.2; P < 0.001) and breed (OR 16.1, CI 2.1–121.5; P = 0.007), and (ii) between B. vogeli and anaemia (OR 11.8, CI 2.3–61.6; P = 0.003). Neither protozoal nor bacterial DNA loads, estimated using qPCR, were positively correlated with anaemia or thrombocytopenia. Haemotropic mycoplasmas were not associated with any haematologic abnormality. Four dogs from the NT were seropositive for Coxiella burnetii, while no dogs were seropositive for Brucella suis or to a panel of Bartonella spp. antigens. Despite directed efforts, Bartonella DNA was not detected in blood from any of the cohorts studied. A sample of dogs from the NT recruited specifically for Bartonella α-proteobacteria growth medium enrichment blood culture were also Bartonella PCR negative.ConclusionsVector-borne pathogens occur in dogs free ranging near Aboriginal communities, with higher detection rates in NT than N-W NSW. The preponderant haematologic abnormalities were anaemia and thrombocytopenia, likely attributable to A. platys and B. vogeli infections, but also probably affected by nutritional, parasitic, lactational and environmental stressors. The absence of Bartonella spp. is of importance to the Australian setting, and work needs to be extended to tropical coastal communities where fleas are present as well as ticks. Dogs living in and around Aboriginal communities may provide valuable sentinel information on disease infection status of human public health significance.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-017-1169-2) contains supplementary material, which is available to authorized users.