A survey of Western Australian sheep, cattle and kangaroos to determine the prevalence of Coxiella burnetii

The objective of this study was to investigate the prevalence of Coxiella burnetii in two domestic ruminant species (cattle and sheep) and the western grey kangaroo (Macropus fuliginosus) in Western Australia (WA). The IDEXX CHEKiT Q Fever ELISA and CFT were used to test sera from 50 sheep and 329 head of cattle for anti-C. burnetii antibodies and 343 kangaroo sera were tested using an indirect ELISA developed specifically for this study. Faecal or urine samples collected from the same animals were tested with two PCR assays to identify active shedding of C. burnetii in excreta. Only two of the 379 ruminant sera had detectable levels of anti-C. burnetii antibodies according to the ELISA while the CFT did not detect any positive samples. In contrast 115 of the 343 western grey kangaroo serum samples were positive when tested with the antibody-ELISA. The first qPCR assay, targeting the IS1111a element, identified 41 of 379 ruminant and 42 of 343 kangaroo DNA samples as positive for C. burnetii DNA. The second qPCR, targeting the JB153-3 gene, identified nine C. burnetii DNA-positive ruminant samples and six positive kangaroo samples. Sequence comparisons showed high degrees of identity with C. burnetii. Isolation of C. burnetii from faeces was also attempted but was not successful. From the results presented here it appears that domestic ruminants may not be the most significant reservoir of C. burnetii in WA and that kangaroos may pose a significant threat for zoonotic transfer of this pathogen.