Why The Heck Do So Many Koalas Have Chlamydia?

Koalas are one of the most popular animals that can be found in Australia, and are certainly one of the cutest.

Koalas And Chlamydia:

These sweet creatures are loved worldwide due to their good looks and wholesome hugging, but did you know that more and more koalas are becoming affected by an awful disease?

That’s right, unfortunately, koalas have become more and more affected by the spread of chlamydia throughout the species, and it’s meaning that more koalas are suffering from issues such as blindness, infertility, and even death!

So why are there so many koalas out there who have chlamydia?

Well, if you’re interested in knowing more about the reasons why koalas have chlamydia, then continue reading through our guide, as we explain all of the reasons that means that so many koalas are suffering from this disease!

Koalas And Chlamydia

Chlamydia has been a long-standing issue for koalas, and now the spread of this disease is affecting more koalas than ever, this debilitating disease is a bacterial disease that is spread predominantly through sexual intercourse, and whilst it is possible for humans to contract chlamydia too, the strain that is ravaging koala populations is slightly different. 

In fact, this disease has become so prominent that some surveys of local populations are beginning to show an infection rate of 100 percent.

The idea of a cute and cuddly animal like a koala having a sexually transmitted disease might be slightly amusing to some people, but the reality is that this disease is causing massive problems for the koala population.

If left untreated, this disease can lead to some horrendous problems for the marsupials, including severe bladder inflammation, complete blindness, infertility, and on top of all of that, death. 

How Are Koalas Treated For Chlamydia?

When it comes to treating those koalas who have contracted chlamydia, it can be an extremely complicated process.

Typically, infected koalas are treated with antibiotics, but this treatment is often far from successful, as it causes the koalas to lose weight and eventually die. 

This is because treatment by using antibiotics has an absolutely awful side effect which is what causes some of the complications that lead to their weight loss and death.

This is because the antibiotics can disturb their gut microbes, which in turn makes it much harder for the marsupial to eat the eucalyptus leaves which make up so much of their diet.

So if they can’t digest these leaves properly, they then can’t digest them properly and take the nutrients they need from them. 

How Did Chlamydia In Koalas Start?

You might be wondering how it was possible for koalas to get chlamydia in the first place.

The idea is that the pathogen containing chlamydia initially found its way to Australia’s shores in the late 18th century when livestock first made its way to the country, there was a large amount of infected livestock, most notably sheep, and the same strain of chlamydia that had infected the sheep was able to infect the koalas as well. 

How Does Chlamydia Spread Amongst Koalas?

Much like how the STD makes its way from human to human, chlamydia spreads its way through populations of koalas through sexual intercourse.

The way in which koalas mate is somewhat abhorrent, as the males will often force themselves onto any koalas they can find in their vicinity, these sorts of social practices mean that a disease like Chlamydia is passed through the population with relative ease. 

Chlamydia can also be passed along from mothers to their young as well, known as joeys, when these young koalas are born and are being fed by their mothers inside their pouch, or by consuming pap, which is a nutritional food made by the mother in form of her faces. 

The disease can also be passed on then too. 

There is also a recent discovery of a virus that exists in koalas that is much like human immunodeficiency virus (HIV), and that koalas that were found to have been infected with this virus, which is known as koala retrovirus type B, were much more likely to contract Chlamydia too. 

Koalas, Chlamydia, And Climate Change

Koalas Chlamydia And Climate Change

So, as you can see, chlamydia makes its way through koala populations with ease, however, as it spreads from animal to animal already, this infection rate is only increased further due to the effects that climate change is having on this already at-risk animal(see also: Animals That Can Change Gender). 

When koalas are subjected to extreme amounts of stress from things such as loss of habitat, loss of food sources, extreme heat and drought, and fragmentation, the spread of chlamydia amongst the species is increased. 

This means that as climate change continues to cause issues for this marsupial, which has seen them lose a lot of their homes, as well as access to their natural food sources, it is also causing severe explosions of infection throughout the wild population of koalas. 

Essentially, the extreme, almost chronic, stress that koalas are experiencing as a result of climate change is causing the koalas’ immune system much weaker than what it normally would be, so their bodies make it much, much harder for them to fight off any disease and infection, which means that what initially might be a incredibly mild case of the disease to become much more severe. 

Are Koalas Endangered?

As a result of the infertility caused by the disease, combined with the disease causing a lot of death amongst the koala population, and the rapid rate in which climate change is affecting this marsupial, it is therefore no surprise then that as of 2022, the Australian government has officially had to declare that the koala is now an endangered species. 

The species has been considered “vulnerable” since 2012, however many activists and campaigners feel that koalas should have been classified as endangered sooner in order to have a better chance to rescue this iconic animal from the clutches of extinction. 

At the current rate, koalas are set to become fully extinct by 2050, which is why this updated classification is so important if they are set to recover from this current state.

Now that they are classified as endangered however, koalas will now benefit from additional protection they previously didn’t have under law from the Australian government, so the hope from many is that this additional protection, as well as a dynamic rescue plan put into place by the government will hopefully see this species make a comeback in the near future. 


So, to summarise, there are a number of reasons why chlamydia is able to spread so rapidly amongst the population, especially when you factor in the promiscuous nature of the marsupial, as well as the adverse effect that climate change is having on the species as well.

So as an animal which is frequently mating with other members of its species, whilst being afflicted with a sexually transmitted disease, and the transmission of the disease between mother and young too, the disease manages to travel easily. 

Olivia Kepner