Scientists reveal that there is a “clear relationship” between the stress levels that koalas (Phascolarctos cinereus) suffer due to habitat loss and their susceptibility to contracting diseases such as chlamydia.
Led by the University of Queensland (Australia), the research focused on koala populations living in the eastern region of the Australian state of Queensland and along the northern coast of New South Wales.
In a paper published in the journal ‘Journal of General Virology‘, the researchers suggest that habitat degradation or loss can increase stress in koalas, with a rise in cortisol hormone levels in their bodies. Koalas with higher cortisol, according to the analyses they conducted, are the ones with greater quantities of KoVR retroviruses, a group of viruses specific to koalas.
KoVR, just like HIV in humans, weakens the immune system of these marsupial mammals native to the Australian forests. As such, it makes them more vulnerable to infections such as chlamydia, which has devastated the wild populations of this species.
Thus, a direct link is drawn between the stress caused by habitat loss and exposure to potentially fatal diseases, which could jeopardize the survival of koalas in the wild, already considered vulnerable to extinction on the International Union for Conservation of Nature’s Red List of Threatened Species.
“We have confirmed that the major threats faced by koalas, habitat loss and diseases, are linked,” stated Michaela Blyton, the study’s first author, in a press release.
“This is very important for understanding how to improve support for the remaining koala populations,” she adds.
The researcher explains that in many koalas KoVR levels remain relatively stable across the two lifespans, and that even if an animal has been successfully treated for a chlamydial infection, KoVR levels do not decrease. Therefore, she notes, it is the rise in KoVR that increases susceptibility to chlamydia, not the other way around.
Thus, the team believes it is urgent to reduce koalas’ stress levels through protection and preservation of their habitats, so that KoVR levels do not rise and, consequently, there is no greater risk of contracting diseases.
“When we look at koala conservation strategies, we must adopt a holistic approach, because disease and environmental factors are interconnected,” Blyton emphasizes.
It is worth noting that this September, for the first time worldwide, a vaccine to protect koalas against infections and deaths caused by chlamydia was approved.
Developed by the University of the Sunshine Coast, the vaccine’s approval by Australia’s veterinary medicines regulator is an important step in the fight against one of the greatest long-term threats to the survival of the country’s iconic marsupial.
