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Aims:  To determine the optimal DNA extraction method for the detection of Coxiella burnetii including the small‐cell variant (SCV) by real‐time PCR (qPCR) in clinical samples. Methods and Results:  A duplex qPCR detecting two Coxiella burnetii gene targets (com1 and IS1111a genes) was developed. Each target in this PCR had a sensitivity of one copy number per reaction. DNA extraction methods were compared on spiked negative samples and included a silica column kit, a chloroform separation prior to a silica column method and a chloroform/phenol separation and DNA precipitation method. Conclusions:  The silica column extraction method was more efficient at recovering C. burnetii DNA, from large‐cell and small‐cell variants, than a chloroform or chloroform/phenol method. The silica column method was useful on spiked human samples including serum, buffy coat and bone marrow samples. Significance and impact of study:  This study demonstrated that a simple column kit method is efficient to use for the detection of C. burnetii in clinical samples including the SCV.

We investigated the role of the western grey kangaroo (Macropus fuliginosus) in the maintenance and transmission of Coxiella burnetii in Western Australia. Sera from 1,017 kangaroos were tested using an indirect enzyme-linked immunosorbent assay (ELISA) for the presence of C. burnetii antibodies. The overall antibody prevalence across 12 locations throughout mid- to southwestern Western Australia was 24.1% (95% CI: 21.6-26.8). Feces from 990 of the same animals were tested using PCR to identify active shedding of C. burnetii in excreta. Coxiella burnetii DNA was detected in 4.1% (95% CI: 3.1-5.6) of samples. Our results suggest that kangaroos are reservoirs for C. burnetii in Western Australia and may contribute to transmission of the organism to domestic livestock and humans.

The aim of this work is to investigate the presence of Coxiella burnetii in Perameles bougainville and their ticks on two islands off Western Australia. Haemaphysalis humerosa, Haemaphysalis ratti, and Haemaphysalis lagostrophi were collected from P. bougainville on Bernier and Dorre Islands from 2005 to 2007; only Amblyomma limbatum was collected from humans over the same interval. One of 13 tick samples and 1 of 12 P. bougainville fecal samples were positive for C. burnetii DNA using quantitative polymerase chain reaction. DNA fragments had >99% similarity to published C. burnetii sequences. Three of 35 P. bougainville sera tested positive for anti-C. burnetii antibodies using enzyme-linked immunosorbent assay. C. burnetii was found in P. bougainville feces and a H. humerosa tick on Dorre Island and Bernier Island, respectively. This is the first reported use of enzyme-linked immunosorbent assay for screening of P. bougainville sera. The risk of zoonotic Q fever infection for human visitors to these islands is considered relatively low, however, appropriate precautions should be taken when handling western barred bandicoots, their feces and their ticks on Bernier and Dorre Islands.

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