My research is focused on various aspects of the health and diseases of koalas, including oxalate nephrosis, Chlamydia and retrovirus, and outcomes following bushfire-related burns.

Oxalate nephrosis, a disease in which calcium oxalate crystals are deposited in the kidneys leading to renal dysfunction (Speight et al, 2013;2014), affects many koalas in the Mount Lofty Ranges population of South Australia. Oxalate nephrosis may have an underlying genetic cause, as well as involve other factors including dietary oxalate (Speight et al, 2013), climate (Speight et al, 2018) and gut bacteria (Speight et al, 2019). Understanding the cause and risk factors of this disease will assist with diagnosis and management of affected koalas.

Chlamydial disease in koalas is devastating populations of koalas on the east coast of Australia. Our research has shown that Chlamydial infection is common in koalas in the Mount Lofty Ranges of South Australia, but causes little disease in these koalas (Speight et al, 2016; Fabijan et al, 2019a). Kangaroo Island koalas have been shown to be Chlamydia pecorum- free, making them a large isolated population of negative koalas (Fabijan et al, 2019a). Understanding more about the infection patterns of Chlamydia in southern koalas will assist with managing this infectious threat to koalas.

Koala retrovirus infects 100% koalas in the eastern states, where it has been shown to be endogenous. In South Australia, koalas have a lower prevalence of retrovirus infection (Fabijan et al, 2019b), and research is continuing to understand its impact in southern koalas, which is based on complex factors such as variant and infection load (Sarker et al, 2019). Koala retrovirus has been associated with the development of lymphoid cancers and may increase the likelihood of Chlamydial infection, so it is important to understand the transmission and disease risk of this infection, particularly in SA koalas (Stephenson et al, 2021).

The Black Summer bushfires in 2019-2020 led to koala deaths in the thousands, but many were also rescued and rehabilitated from their burn injuries. In South Australia, the largest fire was on Kangaroo Island and analysis of medical records showed that 54% of rescued koalas were released following treatment (Funnell et al, 2025; Dunstan et al, 2021). However, burns can affect deeper tissues of the skin in koalas, and smoke can lead to fluid in their lungs (pulmonary oedema) (Baek et al, 2023). Hence more research is needed to support future bushfire rescue operations.

This research on the health of koalas will contribute to their conservation and management into the future.