In which of the following animals does chlamydia naturally occur?

The bacterium Chlamydia trachomatis causes chlamydia and naturally occurs in many species, including koalas. In wild populations, chlamydial infection can occur due to contact between infected and uninfected individuals or through transmission from mother to joey during birth.

In addition to natural occurrence, human activity can increase the risk of koalas contracting chlamydial infections. Koala habitats are often fragmented due to urbanization and other land-use changes, which can lead to increased contact between infected and uninfected individuals. Additionally, human-induced stressors such as habitat destruction and climate change can weaken koala immune systems and make them more susceptible to disease.