Document ID: chunk:federal_register_of_legislation:F2022L00555:body:0:p56
Version: federal_register_of_legislation:F2022L00555
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local population recovery (Beyer et al. 2018). Further research into novel approaches to human social behaviour on dog-Koala interactions (Rundle-Thiel et al. 2019) and Koala aversion training for dogs (David et al. 2019) may also provide some new tools for reducing mortality and trauma from dog attacks.

Disease prevalence in the Koala
Koalas carry a range of pathogens and parasites. Of concern are infections by the bacterium Chlamydia pecorum that leads to chlamydial disease and the Koala retrovirus (KoRV) (Bachmann et al. 2014; Fabijan et al. 2019; Grogan et al. 2017, 2018; McCallum et al. 2018; Quigley and Timms 2020). Also for consideration are Phascolarctid herpesviruses, associated with predisposition to disease in Koalas in Victoria, but for which no information exists in New South Wales (Kasimov et al. 2020; Stalder et al. 2015); Trypanosomes, some of which appear to exacerbate disease but for which no information exists outside of Queensland, and Sarcoptes scabeii, which causes sporadic epidemics of mange, particularly in Victoria.
Chlamydia causes conjunctivitis (pink eye) leading to blindness, urinary tract disorders (wet bottom/dirty tail), pneumonia and infertility in females (Phillips 1990; Polkinghorne et al. 2013; Fabijan et al. 2019). This bacterium is one major reason for admissions of Koalas for clinical care in some regions, the other being dog and vehicle trauma (this section) (Beyer et al. 2018; Gonzalez-Astudillo et al. 2019). Chlamydial infection is almost ubiquitous among Koala populations (McCallum et al. 2018; Polkinghorne et al. 2013; Quigley and Timms 2020). A review into the status of research into disease of the Koala found that Kangaroo Island (n=170) was the only region with no evidence of chlamydial disease (Fabijan et al. 2019), though there is evidence indicating there are some increasing Clamydia-free populations in New South Wales (such as Campbelltown, some areas of the Blue Mountains and potentially Mumbulla State Forest). Elsewhere, where more than five Koalas were tested in an area, prevalence of Chlamydia infection ranged from 21% to 88% (Quigley and Timms 2020).
Given it commonly causes infertility, chlamydial disease is considered a major cause of decline in many contemporary populations (Rhodes et al. 2011; Robbins et al. 2019) and can be expected to exist with minimal impact (as it does in much of Victoria); cause declines on its own or when predisposed to by other pressures; or add to, amplify, or limit recovery from impacts of other pressures. Along with harvesting, it likely contributed to the decimation of past Koala populations during 1887–89, 1900–03 and throughout the 1920s and 1930s, and was thought to be a component of the Koala's natural history (Phillips 1990), although recent genomic comparisons suggest that some Koala C. pecorum strains may originate from domestic livestock (Bachmann et al. 2014).