Molecular detection and characterization of Coxiella burnetii in Australian native wildlife species

Abstract

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii with domestic ruminants considered the main infection source for humans. Coxiella burnetii infection in Australian native wildlife (ANW) species has been demonstrated, however their role as reservoirs remains unclear. This study aimed to determine the prevalence of C. burnetii DNA in tissues, swabs, and secretions from ANW, (primarily marsupials from eastern Australia), and further understand the pathogenesis in these species by identifying tissues infected and potential shedding routes. The study utilized an optimized multiplex quantitative PCR assay targeting three C. burnetii genes and a stringent classification system that prioritized specificity to overcome false positives known to occur due to Coxiella-like endosymbiont species. Of the 141 animals examined, one eastern gray kangaroo cloacal swab tested positive for C. burnetii DNA (at ~11 genome equivalents per reaction) in all three genes. Four animals were classified as suspect with amplification in two genes at a lower copy number. Genotyping of the definitively positive animal returned a C. burnetii genotype previously associated with human Q fever cases, which underscores the importance of Q fever vaccination where available for individuals in contact with wildlife, given the potential severity of the disease in humans.

Keywords: Coxiella burnetii; Australia; Q fever; macropods, Australian native wildlife, multiplex qPCR.

Figure 1.

The geographical locations in NSW (Case studies 1a, 1c, and 2), the ACT (Case study 1b), and QLD (Case study 3), where wildlife samples were obtained and subsequently analysed for the presence of C. burnetii DNA.