Document ID: chunk:federal_register_of_legislation:F2022L00555:body:0:p58
Version: federal_register_of_legislation:F2022L00555
Segment Type: other
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Character Range: 184568–187629

to cause cancers such as lymphosarcoma, which are common in Koalas (McEwen et al. 2021) and it is likely that deleterious insertions interfere with a range of immune and metabolic genes, though evidence for this is preliminary. Given its evolutionarily recent introduction (<50,000 years) (Ishida et al. 2015), these heritable insertions are not stable in the genome and it is likely that deleterious insertions can become concentrated and more strongly expressed in fragmented or inbred populations, in a fashion similar to recessive genetic defects. Association with a range of KoRV aspects have been associated with chlamydial disease (Fabijan et al. 2017; Ishida et al. 2015; Quigley et al. 2019), although evidence is somewhat equivocal, likely due to the multifactorial nature of disease and the complex nature of retroviral infection.
Control of these diseases in wild populations centres on managing other additive or amplifying threats and pressures to improve the resilience of populations and prevent introduction of novel strains of pathogen to populations. At very local scales, removal or treatment of diseased animals, or vaccination to reduce transmission, may be feasible but the latter is still in the clinical and field evaluation phase. There is a deficiency of field-based population-level disease studies across the geographical range that have examined the prevalence of chlamydia and the underlying cause of disease in Koala populations and its relative importance on Koala demography and individual fitness, population and regional-level dynamics (Grogan et al. 2017, 2018; McCallum et al. 2018; Narayan and Williams 2016). Further studies on chlamydia, KoRV and other emerging Koala diseases in wild populations, particularly in relation to identifying pathogen, host and environmental drivers and associations, are needed to guide conservation management and prioritise investment. Furthermore, understanding the interactions between Koala genetic traits, pathogen strains and virulence traits is needed to inform risk management and design of future management actions.

Diseases of Koala habitat
An emerging disease that affects Koala habitat is Myrtle Rust, a plant disease caused by the introduced fungal pathogen Austropuccinia psidii. Myrtle rust was first detected in Australia in 2010 and affects plant species in the family Myrtaceae (eucalypts, lillypillies, paperbarks and tea-trees) which dominate many Australian ecosystems. The pathogen spreads easily via wind, animals and humans. The disease leads to defoliation, loss of reproductive capacity and death; and seedlings are particularly vulnerable (Makinson 2018). The disease is naturalised along the east coast of Australia, with the most serious infections in New South Wales and south-east Queensland (Makinson 2018). Although not yet identified as a threat to the Koala, emerging diseases like Myrtle Rust that impact the health of eucalypt ecosystems may indirectly affect the Koala via decline in habitat quality, although impacts are likely to be minor compared