Until now, antibiotics have been the only treatment available outside clinical trials, and have to be specially made up. These can also have serious and sometimes deadly side effects. They can kill the koala’s microbiome, which can be fatal if not carefully managed, Lett says. In addition, after antibiotic treatment, once animals recover and are released back to the wild, they can be reinfected.
According to Phillips, research has found the vaccine reduces likelihood of koalas developing symptoms of chlamydia during breeding age, and lowers mortality rates in wild populations “by at least 65%”.
Why are koalas so badly impacted by chlamydia?
It’s unclear how and when koalas first caught the highly contagious disease. Various theories include the possibility it was introduced through infected livestock after European settlement, Phillips says.
Wildlife veterinarian Dr Leanne Wicker says the sexually transmitted disease, which affects both males and females, can be “really nasty”. “Infected koalas can become blind and infertile.”
She says the vaccine’s approval is good news for northern populations especially.
“They’re already suffering significantly from habitat loss, bushfires and the impacts of climate change – we know that their population is dwindling. Chlamydial disease is an additional stress that the population just doesn’t need.”
The severity of chlamydia outbreaks among koalas is worse in Queensland and New South Wales, where the species is listed as endangered.
In Victoria, where there are not enough trees to sustain larger local populations, symptoms are often not as severe. More research is needed to understand the significance of chlamydia for southern populations.
What are the hopes for the koala vaccine?
Lett says the new approval offers hope to wildlife carers. “It’s really hard, especially if you raise joey koalas to put them out there, and then pick them up a few years later when they’re badly affected.”
Seeing affected animals, Lett says, is “heartbreaking”.
Phillips says the vaccine rollout to at-risk koala populations would ideally occur alongside other measures tackling threats such as deforestation, predatory animals and car accidents.
“You would need to go into a population that would be at risk of becoming locally extinct and tackle all of the threats that those koalas are facing.”
We need to remember how fragile the species is, says Lett. “We need to think big picture with them, and think about what we’re doing to their homes.
“I hope things do change, with the help of the vaccine.”
