Yes, Really – Koalas Are Getting Vaccinated Against Chlamydia

They've struggled with the sexually transmitted infection for years.
Adi Adi / 500px via Getty Images

Australia is officially stepping in to reduce chlamydia among wild koalas.

Yes – this may sound unlikely, but these fluffy marsupials have a serious problem with this sexually transmitted bacterial infection, which is rampant across the species.

According to Live Science, some populations have a 100% rate of infection, although other scientists told the Press Association (PA) that around half of wild koalas across Queensland are infected.

Chlamydia can lead to blindness, severe bladder inflammation, infertility and death.

Yet antibiotics for the infection can upset koalas’ gut microbes and affect their ability to eat eucalyptus leaves.

So, Australian scientists are going to start administering a single-shot chlamydia vaccine to them instead.

Samuel Phillips, a microbiologist at the University of the Sunshine Coast, who also helped to develop the vaccine, explained that this was a significant move because the STI can be so devastating for a species already dwindling in numbers.

He said: “It’s killing koalas because they become so sick they can’t climb trees to get food, or escape predators, and females can become infertile.”

The decision to vaccinate the animal was approved by multiple government bodies across Australia’s agriculture department and New South Wales’s planning and environment department.

Scientists plan to catch, vaccinate and monitor around half of the koala population in the Northern Rivers region of New South Wales, vaccinating around 50 animals.

They also intend to evaluate how many koalas they need to vaccinate to meaningfully reduce infection and disease across a three-month programme.

Chlamydia increases the risk of infertility among koalas, who are already an endangered species
Chlamydia increases the risk of infertility among koalas, who are already an endangered species
Marianne Purdie via Getty Images

Healthy koalas will be caught in harmless traps, before receiving anaesthetic and shots of the vaccine. They will then be kept under observation for 24 hours after they wake up to make sure there are no unexpected side-effects.

Before being released, the koalas will be marked with pink dye.

The species has been declining in numbers for the last two decades and was officially declared “endangered” in February 2022.

A 2020 assessment from the New South Wales government warned they could be extinct by 2050 due to disease, habitat loss and road collisions.

It’s not entirely clear why koalas are so prone to the the disease, but scientists believe they may have caught it from exposure to infected sheep and cattle poo.

It can then spread via sex or pass from mother to offspring.

Habitat destruction also increases animals’ stress levels and can weaken their immune systems, making them more susceptible to disease.


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