Environmental stress causes poor immune response to disease: climate change is causing koalas to die of chlamydia
The koala, Australia’s iconic marsupial, is in danger of disappearing from the face of the earth. In fact, for some years more and more animals are infected with chlamydia, a sexually transmitted disease.
What is happening to koalas
Chlamydia is a very dangerous sexually transmitted disease: it infects more than 100 million humans each year, and can even cause infertility if left untreated.
For koalas, the symptoms are blindness and painful cysts in the reproductive tract, which can lead to infertility, but also to death. There is an antibiotic treatment, but in koalas it has very serious side effects: it can in fact destroy the delicate intestinal flora that koalas need to consume their basic diet of eucalyptus leaves, leading some to starve to death after being treated for chlamydia.
The disease has spread in very slow and silent over the years: in 2008, only 10% of Australian koalas had chlamydia: a study conducted in the rural area of Gunnedah, in southeastern Australia, discovered this. By 2015, the number had risen to 60. Today, 85 percent of koalas are infected. “The situation is very serious because even if they survive, infertility comes into play: practically every female that is infected becomes sterile in two years maximum,” explained Mark Krockenberger, professor of Veterinary Pathology at the University of Sydney.
For an animal already put at serious risk by the disastrous fires that recur cyclically in Australia, chlamydia does very serious damage. Now scientists are considering a vaccine.
Climate change is making it worse
As in many parts of the world, Australia’s climate crisis has led to devastating wildfires, droughts and heat waves. And that makes koalas more susceptible to many diseases. There is evidence that when these animals are subjected to stressful environmental situations, chlamydia spreads much more rapidly. In fact, increases in cases in the Gunnedah population have corresponded with a series of heat waves and droughts.
Peter Timms, professor of microbiology at the University of Sunshine Coast in Australia, said that once koalas produce more stress hormones due to environmental problems, chlamydia infections often progress from a minor problem to a serious one: a combination of habitat loss and climate change is causing koalas to experience “chronic stress” that depresses their immune systems and leads to a poor immune response to chlamydia.
This is certainly not the first time climate change has led to long-term effects on the animal kingdom.