A chlamydia epidemic is proving to be an alarming threat to our koalas but new genetic research could be the key to their conservation.
The koala has been listed as a vulnerable species by the International Union for the Conservation of Nature (IUCN) since 2016 and it is estimated that there are only 100,000 left in the wild today.
Of the 1,000 individuals arriving annually in New South Wales and Queensland wildlife hospitals, 40% have untreatable late-stage chlamydia that makes the koalas impossible to rehabilitate.
Researchers tracking the population of koalas on the Koala Coast (a stretch of 375 square kilometres south of Brisbane) have found that 52% of the koalas observed showed chlamydia-like symptoms.
New research released today by the CSIRO finds that 61% of koalas in Victoria's South Gippsland region are carrying the disease (one of the highest prevalence rates that has been observed in a population).
Lead researcher Dr Faye Wedrowicz told BuzzFeed News that her team decided to look at koalas in the region because they are promising to the future of the species in Australia.
"The South Gippsland koala population is unique in Victoria because it's got quite high genetic diversity."
Wedrowicz said she was surprised at the high rate of chlamydia amongst the Gippsland koalas.
The infection can lead to blindness, severe bladder infections, infertility and death in koalas.
And no, the strain of chlamydia that infects koalas is not the same that infects humans but it is sexually transmitted in the same way.
Genetic evidence from the chlamydia bacteria suggests that koalas were infected by the disease through transmission from livestock (specifically sheep). Although one paper on the topic states the "mechanism of transmission between livestock and koalas currently eludes us".
The interspecies chlamydia transmission was likely related to faecal contamination of a koala's food source and probably not what we're all currently thinking.
Koalas appear to differ in their response to chlamydia infection, with some not affected by the disease and others dying of it.
Professor Katherine Belov of Sydney University and one of a team of Australian and international researchers to have recently sequenced the koala genome, told BuzzFeed News that this is all down to their genetics.
"100% of the koalas could have chlamydia and some of them have no symptoms at all, others develop some symptoms and then clear the disease. And others get very sick and end up dying and we know it's differences in their immune responses," she said.
The sequencing of the koala genome could provide vital clues about their immune systems and how to save their population from chlamydia.
"Having this information means that we'll be able to really zero in on what's going on there and understand why some animals recover and others don't," said Belov.
So, how do you actually sequence a genome?
It's a laborious process that involves breaking down DNA into small, readable segments, figuring out the sequence of the base pairs (DNA building blocks) in each segment and then reassembling all of the parts using a super computer.
To sequence the koala genome, the researchers used two populations of koalas: ones that responded well to a chlamydia vaccine trial and another that didn't.
"We identified three genes in particular that seem to make a difference in whether an animal responds to a vaccine or not," said Belov.
This information is useful because conservationists can now improve vaccines as well as predict whether they'll be useful in certain populations.
Belov says the sequence has now been handed over to New South Wales' Koala Strategy to help conservation efforts.
However, Belov suspects that ridding our koala population of chlamydia will require more than genetic assessment and vaccine programs.
"We're also looking at the role that stress plays. I think stress is definitely a factor – of course our koala populations are quite stressed because of urbanisation and habitat clearance."