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Australia is the only place on the planet where koalas can be found in the wild, and there are a number of factors that have led to them being listed as endangered in the country. That includes the chlamydia epidemic that has ravaged the population, but there may be some hope on the horizon.
There are a number of animals that are only native to Australia. Kanagaroos may have managed to cement themselves as the country’s unofficial symbol (one, along with an emu, managed to secure a spot on its coat of arms), but koalas have given their fellow marsupials a run for their money.
The continent was home to an estimated 8 million koalas at the start of the 20th century, but as of 2024, it was believed that number was somewhere between 224,000 and 524,000.
There are a number of factors that have contributed to that dramatic decline. Koalas were hunted for their pelts at the start of the 1900s before the practice was banned due in large part to the backlash to “Black August,” a month-long, state-sanctioned campaign in Queensland in 1927 where at least 600,000 of the animals were killed.
Koalas have also had to grapple with deforestation tied to urbanization, wildfires, and climate change (the last two of which have become inextricably linked), but there’s also a somewhat surprising threat that’s played a role: chlamydia, an issue that is on the verge of being addressed head-on.
Australia has approved the first-ever vaccine designed to stop the spread of chlamydia within its koala population
It’s not entirely clear how koalas contracted chlamydia in the first place, although experts believe the current epidemic can be traced back to cattle and sheep who spread the disease in the 1780s. It has decimated a population that can suffer from blindness, infertility, and bladder inflammation after being infected, and it is the second-most common cause of death for koalas aside from being hit by a car.
If you watch Last Week Tonight with John Oliver, you may have been aware of the issue thanks to an episode that aired in 2018 where he learned the Irwin family had decided to name the Koala Chlamydia Ward at the Australia Zoo in his honor.
Experts say some populations have a 70% infection rate. The STD can be transmitted through that particular activity but can also be passed to young koalas through “pap” (the fancy word for the poop that joeys eat to develop the gut microbes needed to digest the eucalyptus their diet centers around) or by simply being in their mother’s pouch.
According to the BBC, researchers have spent over a decade developing a vaccine specifically designed to inoculate koalas from chlamydia, and the one developed by scientists at the University of the Sunshine Coast in Queensland recently received approval from federal regulators.
The approval came after a number of trials that determined the vaccine “decreased mortality from the disease in wild populations by at least 65%.” That certainly seems promising, although the researchers noted they will need to raise funds for the costly process of tracking down and injecting the koalas that will benefit from the development.