Chlamydiae are diverse and enigmatic bacteria that infect a broad range of hosts, including the koala (Phascolarctos cinereus).

Chlamydial infections and associated disease remain a major welfare concern for and threat to the sur­vival of koalas. Although multiple threatening processes such as trauma (motor vehicle accidents, dog attacks), urbanisation, disease, bush fires and climate change have been documented or suggested as causes of declining koala populations in peri-urban areas (Narayan and Wil­liams 2016; McAlpine et al. 2017), modelling suggests that chlamydial disease control may be important in prevent­ing population declines and for restoration of some popu­lations (Rhodes et al. 2011).

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