That's right, chlamydia. The situation is so dire, in fact, that experts fear the koala may become extinct in a few decades if a vaccine isn't developed.
The disease's effects include severe conjunctivitis (or "pink eye"), incontinence, prostatitis and kidney damage. Chlamydia is weakening koalas to the point where they no longer have the energy to survive. It can also cause conditions such as urinary tract infections that can impair the reproductive system. Zoologists say 30 to 45 percent of female koalas have been left infertile.
While nobody knows how koalas first came to be infected with chlamydia, some researchers speculate koalas may have been exposed to infected mammals at some point in their evolution. The disease spreads among koalas through male-male and male-female sexual contact, as well as orally from mother to young during child rearing.
Though the rate of infection has historically been quite high, the expression -- or display of symptoms -- has been low. It's with extreme stress among the animals, however, that the disease then expresses itself.
And over the past decade, koalas have been stressed.
They've lost vast portions of their habitat to human development. Crammed into ever-smaller fragments of land and in areas with severe human encroachment, such as the "Koala Coast" in southeastern Queensland, the koala population has been almost completely wiped out.
"We're looking at a situation where koalas in southeast Queensland would be functionally extinct," said William Ellis, a researcher at the University of Queensland, in an interview with AOL News.
The Australian Koala Foundation estimates that there are fewer than 80,000, and potentially as few as 43,000, koalas left in Australia today.
Since there is no vaccine, koala conservationists can only react to the chlamydia epidemic, treating a small percentage of the animals with long-term antibiotics and anti-inflammatories before releasing them into the wild. A spokesperson at Australia Zoo Wildlife Warriors, a leading conservation group, said koalas with severe reproductive disease or other incurable diseases are euthanized.
While researchers are working on a vaccine, it may arrive too late. And some fear that a vaccine could harm the animal's specialized digestive tract, which contains healthy bacteria that break down a diet rich in eucalyptus leaves.
While conservationists address the epidemic, the fate of the koala has gone largely unnoticed outside of Australia. That may suit the Australian tourism industry just fine, as koalas are estimated to have a $1 billion impact on the tourism industry.
What tourist, after all, would want to be photographed with an animal known for its chlamydia?
"It's a benefit to the tourism industry that you don't see koalas with disease," Timms said.