Diseases, particularly Chlamydia and koala retrovirus, play a key role in the decline of koala populations across northeastern Australia. South Australia (SA) koalas have a lower incidence and severity of these diseases, with Kangaroo Island free from Chlamydia. Therefore, these koalas may serve as insurance populations for the future of the species, and it is of great importance to undertake further health status and disease interaction research in SA koalas.