Australia's iconic koalas are facing an unprecedented threat: chlamydia. This bacterial infection is responsible for half of all koala deaths in the wild, pushing populations towards extinction in regions like South East Queensland and New South Wales. Infection rates in these areas often exceed 50%, reaching as high as 70% in some colonies. Now, a groundbreaking development offers a lifeline: a world-first chlamydia vaccine has received approval for widespread use.
Developed over a decade by researchers at the University of the Sunshine Coast, this single-dose vaccine offers a crucial defense against the devastating effects of chlamydia, which include blindness, infertility, urinary tract infections, and ultimately, death. Previous attempts to treat chlamydia with antibiotics proved problematic, often interfering with the koalas' ability to digest eucalyptus leaves, leading to starvation.
The vaccine, based on Chlamydia pecorum's major outer membrane protein (MOMP), provides three levels of protection. It reduces the likelihood of infection, prevents the disease from progressing to clinical stages, and in some cases, even reverses existing symptoms. Extensive trials on hundreds of wild and captive koalas, including a large-scale study spanning multiple generations, demonstrated a remarkable 65% reduction in chlamydia-related mortality in wild populations. This research, published last year, provided crucial data for regulatory approval.
The Australian Pesticides and Veterinary Medicines Authority's approval marks a significant victory for koala conservation. While habitat loss, attacks by predators, and road accidents also contribute to koala decline, this vaccine directly addresses a major killer. The success of this vaccine serves as a beacon of hope for the future of these beloved marsupials, offering a crucial tool in the ongoing battle to protect Australia's unique biodiversity and prevent the extinction of this iconic animal. The vaccine's rollout is a pivotal moment in koala conservation efforts, representing a significant step towards securing their long-term survival.
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Originally published at: https://edition.cnn.com/2025/09/10/science/koala-chlamydia-vaccine-rollout-intl-scli
