Koalas, iconic Australian wildlife, face numerous challenges threatening their existence. Among these, a significant health concern, often referred to as “koala strain,” poses a severe risk to their survival. Understanding this complex issue is important for effective conservation efforts.
Understanding the Term “Koala Strain”
The term “koala strain” does not describe a single pathogen. Instead, it refers to bacterial pathogens, primarily Chlamydia pecorum and, less frequently, Chlamydia pneumoniae, which cause widespread disease in wild koala populations. These bacteria are distinct from the Chlamydia species that infect humans.
The Diseases Affecting Koalas
These bacterial infections lead to chlamydial diseases that severely impact koala health. The infections manifest in two primary forms: urogenital tract disease and ocular disease. Up to 100% of koalas in some populations have tested positive for the disease.
Urogenital Infections
Urogenital infections affect the reproductive and urinary tracts. In females, this can result in infertility due to inflammation and scarring of the reproductive organs, hindering breeding success. Both male and female koalas can develop urinary tract infections, causing pain and discomfort, often leading to a visible “wet bottom” syndrome from constant urine leakage and fur staining around the rump.
Ocular Disease
Ocular chlamydial disease presents as conjunctivitis, characterized by inflamed, red eyes and discharge. As the disease progresses, it can invade the cornea, leading to corneal scarring and blindness. Blind koalas struggle to find food or escape predators, often leading to starvation or other fatalities, necessitating euthanasia. These conditions collectively reduce life expectancy and severely impact population viability.
Combating Koala Strain
Combating “koala strain” involves treatment, vaccination, and broader conservation strategies. Antibiotics are used to treat infected koalas, requiring long courses and captive care. Antibiotic use also carries the risk of disrupting the koala’s gut microbiome, affecting their ability to digest eucalyptus leaves.
A chlamydia vaccine for koalas has seen significant progress. Researchers at the University of the Sunshine Coast developed a protein-based vaccine, with trials showing it can reduce infection and prevent healthy koalas from developing the disease. A large-scale, decade-long study involving over 680 wild koalas confirmed the vaccine’s effectiveness, reducing disease development during breeding age and lowering deaths by at least 65%. This vaccine pushes back the average age of disease onset by more than three years, protecting koalas during their main reproductive period. Wildlife hospitals and research institutions play a central role in these efforts, administering the vaccine to koalas before their release back into the wild.