Sam the Koala, made famous as the global face of Victoria's bushfires after being saved by a CFA firefighter is facing a new battle for survival.

Despite making a strong recovery at the Southern Ash Wildlife Shelter after being plucked from the scorched earth by volunteer, David Tree, Sam is now facing a life-threatening illness, The Herald Sun reported.

She is expected to undergo surgery this week to treat cysts as a result of urogenital chlamydiosis, a life-threatening disease that can cause infertility, urinary tract infections and blindness.

Southern Ash Wildlife Shelter spokesman Nic Pullen said the turn of events was extremely distressing.

"Sam was making good progress with her recovery, her burns had healed and she had even developed a strong maternal instinct taking care of some of the orphaned joey's admitted to the shelter over the past several months,” Mr Pullen said.

“The discovery of cyst's due to Chlamydia is very upsetting for everyone involved in Sam's recovery."

Sam’s image was flashed around the world, raising hundreds of thousands for the CFA, while a video of Mr Tree crouching down to offer the furry marsupial a gulp from his water bottle was a huge hit.

Up to 50 per cent of the koala population is affected by the disease, with past vaccines proving unsuccessful.

Mr Pullen said Sam’s prospects would be known by Friday.

Source: Herald Sun