A non-invasive tool for assessing pathogen prevalence in koala (Phascolarctos cinereus) populations: detection of Chlamydia pecorum and koala retrovirus (KoRV) DNA in genetic material sourced from scats

Pathogenic diseases may threaten the viability of wild animal populations, especially when already vulnerable. The mitigation of risks associated with pathogenic infections in populations is an important factor in conservation strategies. Koalas are of conservation concern across the north of their range and are affected by two main pathogens; Chlamydia pecorum and the koala retrovirus (KoRV). This study tested whether DNA from C. pecorum and KoRV could be detected in genetic material isolated from koala scats. Detection of C. pecorum in scat isolated DNA samples was compared with results obtained from urogenital swabs collected from the same individuals as part of an independent study. The ability to detect KoRV in scats from both northern and southern regions of the koala’s range was also assessed. There was a high level of concordance (5/6) between the detection of C. pecorum in DNA isolated from scats and urogenital swabs from the same individual. In positive samples, C. pecorum ompA genotypes were identical between DNA from scats and urogenital swabs in two out of three cases. In samples from the south of the koala’s range, KoRV copy number was higher in DNA isolated from scats compared to DNA isolated from ear tissue, potentially indicating the detection of horizontally acquired infections. Our results demonstrate the ability to detect C. pecorum and KoRV in DNA isolated from koala scats. This method will be useful for studying the prevalence, transmission and impact of these pathogens in wild populations which may subsequently inform conservation management strategies.