Koalas in eastern Australia are cute, cuddly, and suffering from chlamydia, which has led to severe inbreeding that's threatening them with extinction.

These pouched mammals were hunted during the 1920s and 1930s, and their populations plunged 30 percent since 1990, according to CBS News. Consequently, their populations are now smaller and scattered, leading to a host of other problems.

"The populations within that group become severely inbred and then they lead to other problems," said Karen Nilsson, head koala keeper at Lone Pine Koala Sanctuary in Australia.

These other problems include chlamydia, a sexually transmitted disease that can cause infertility and blindness. Koalas with chlamydia are easily spotted by their red eyes.

And with their woodland habitat continually shrinking thanks to human activity, the risk of spreading this disease amongst each other increases, as does the likelihood of koala die-offs.

According to koala conservationist Adam Polkinghorne, "there are koala populations that have experienced localized extinctions across its home range."

Polkinghorne is currently working on a chlamydia vaccine for these marsupials that can hopefully ensure the survival of this species.

"The idea of the vaccine is that we are going to be able to train the immune system of koalas such that if they're ever exposed to this infection in the wild, their immune system will be able to defend themselves against the infection," he said.

On top of worrying about contracting chlamydia, koalas also have to deal with gradually losing more and more habitat, a problem considering that each koala needs 100 eucalyptus trees to survive.

"The loss of their habitat not only loses where they live, it loses what they eat too," Nilsson added. "You lose that, you lose everything."

Koalas sleep 18 to 20 hours a day and they eat a lot - more than two pounds of eucalyptus leaves daily, according to National Geographic.

If more isn't done to protect these inbreeding mammals from spreading disease among their populations, koalas could become extinct in the near future.

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