Australia's koalas are being threatened by a deadly chlamydia epidemic, which affects up to 88% of individuals in some mainland populations. The disease is caused by the bacterium Chlamydia pecorum and can lead to blindness, infertility, pneumonia, and often death. However, Kangaroo Island, a disease-free island enclave, may hold the key to koalalas' survival. Researchers hope to improve the genetic diversity of these koalos and introduce them to other low-chlamydia areas of Australia to tackle the current plight. Despite being listed as vulnerable by the International Union for Conservation of Nature, Australia's population has been declining steadily for decades and now mostly survives in small, fragmented populations. A new vaccine approved in 2025 could offer genuine hope for wild populations, but it remains a formidable challenge.