On the table, unconscious on a pillow, the male koala name Joe Mangy looks calm His watery, red eyes are the only sign of his illness, while tubes emerge from a mask covering his face and a vet listens to his chest with a stethoscope.

Eight days earlier, Joe – who is about two years old – was found wandering in the middle of a suburban street. Dazed and confused, with his eyes almost stuck with mucus, the koala was rushed to Currumbin Wildlife Sanctuary hospital.

Surrounded by rainforest on Queensland’s Gold Coast, at Australiathe park is full of such koalas. Outside the clinic, in a ‘Koala Rehabilitation Centre’, a three-year-old marsupial recovering from a hysterectomy is covered in eucalyptus leaves. “It saved her life, but she can’t reproduce,” says chief vet Michael Payne.

According to the BBCthis hospital is ground zero of a grim epidemic chlamydia which kills thousands of koalas and renders even more sterile, driving them to the brink of extinction. But it is also at the center of a desperate bid to save them with a vaccine. An effort that, after more than a decade, is still constrained by bureaucratic regulations while financial resources are running out.

The biggest and deadliest threat

Even a few decades ago, spotting a koala cuddled up against a backyard tree was not uncommon in Australia. They used to be plentiful on the country’s populous east coast, but in recent times the species has suffered a dramatic decline – in some places it has declined by 80% in just 10 years. Land clearing and urbanization leave marsupials hungry and homeless, while natural disasters suffocate or char them en masse.

“But the main cause is chlamydia which has increased tremendously – almost exponentially,” says Dr Payne, who has run the Currumbin clinic for more than 20 years. “There are days when you euthanize piles of koalas that come in completely damaged,” he explains.

Estimates vary – koalas are notoriously difficult to count – but some groups say there are only 50,000 of the animals left in the wild, and the species is officially listed as “endangered” across most of Australia. There are now fears that the animals will become extinct in some states within a generation. Dr Payne remembers with nostalgia the “early days”, when his hospital only saw a few koalas a year and now treats 400.

“There are so many coming through the door that the team has started giving them two names,” says a veterinary nurse, hugging Joe Mangy as he wakes up from anesthesia. “His last name is an allusion to the condition of his eyes when he first arrived,” she explains.

Of the main reasons koalas are admitted to hospital – vehicle collisions, pet attacks and chlamydia – bacterial infection is the biggest and deadliest. It leads to conjunctivitis for koalas like Joe Mangy, but presents as a genital and urinary tract infection for others. Particularly unlucky animals get both at the same time. At worst, the ocular form can be so bad that koalas go blind and starve to death, while the genitourinary infection produces giant cysts filled with fluid, so “unpleasant” daily bodily functions like urination make the animals cry out in pain.

“Their reproductive system collapses,” explains Dr. Payne. If caught early enough, treatment is an option, but this alone is a potentially fatal ‘nightmare’ as antibiotics destroy the gut bacteria that allow koalas to digest the otherwise toxic eucalyptus leaves – their main food source their.

But at the species level, the disease, which is spread through bodily fluids, causes even more destruction.

Vaccine to combat chlamydia in koalas and avoid euthanasia

Chlamydia is not uncommon in animals, but the spread and intensity of the disease among marsupials is unparalleled. Experts estimate that around half of the koalas in Queensland and New South Wales may be infected, but just one suburb away from Currumbin, in the suburb of Elanora, the figure has exceeded 80%.

This is the sickest population in the region and the numbers have “dropped precipitously”, says Dr Payne. “It’s a disaster,” he notes.

Enter Queensland University of Technology (QUT) and its vaccine, which aims to prevent and treat chlamydia in koalas and has been almost two decades in the making.

Together with Currumbin, they are trying to save Elanora’s koalas from oblivion: they capture 30 young ones and vaccinate them, before recapturing them at three-year intervals to monitor their health.

So far, only three of the vaccinated koalas in this research trial have contracted the disease, although all have recovered, and encouragingly, more than 24 young koalas have been born – bucking the infertility trend.

Currumbin also vaccinates every koala that comes through its hospital and has reached around 400 koalas this way.

But treating and vaccinating each koala with chlamydia costs them about A$7,000 (£3,500, $4,500). Capturing, vaccinating and monitoring each of Elanora’s wild koalas costs essentially twice as much.