Ten months on from the huge news that a chlamydia vaccine had been approved for Australia's koala population, an 18-month-old female known as Bamse has become the first to receive the groundbreaking medicine in a new double-dose format that makes large-scale treatment possible.
Bamse – Norwegian for "teddy bear" – was captured from a wild population in Burleigh, Queensland, and taken to Currumbin Wildlife Hospital, where she was sedated and treated. She returned home later that same day, sporting a collar with GPS tracking so she could be monitored to test the vaccine's efficacy.
"Bamse was a great candidate, a young female koala, the poster child for the future of the species," says Dr Michael Pyne OAM, Senior Vet at Currumbin Wildlife Hospital. "To protect her with the vaccine implant is exactly what we want to be doing. We'll be monitoring her over the next six months. It'll be exciting to see her when she gets her first joey."
The vaccine is actually a double dose that pairs an injection with an implant. The implant, created by scientists from the Queensland University of Technology, breaks down over 30 days to release the second dose, which takes the headache out of recapturing one-time-vaccinated wild koalas to give them further treatment.
"We've been working with vaccines against chlamydial disease in koalas for over five years now, and this is a massive breakthrough where we are turning a two-injection vaccine into an injection and an implant that can be all applied in one examination," says Dr Pyne. "It’s truly a remarkable moment."
While koalas getting chlamydia has been the source of many jokes, it's a deadly serious health problem. It's estimated that around 50% of Australia's remaining koalas are infected, but the rate his highly population-specific. So while some groups of animals have little infection, others may see up to 90% of koalas affected.
Two types of chlamydia affect koalas – Chlamydia pecorum and C. pneumoniae – but the predominant infection is the result of the pathogen C. pecorum. It can be asymptomatic, but it can also lead to blindness and, in females, infertility.
Infertility is a huge blow to the iconic species, which is steadily moving towards extinction. While the IUCN Red List considers the koala (Phascolarctos cinereus) "vulnerable", with numbers decreasing, that doesn't necessarily reflect what has ecologists really concerned.
Overall population is one thing, but it's not the true picture. Accelerated habitat loss has led to increasingly fragmented and isolated groups of koalas predominantly spread across a vast area along Australia's eastern coast. It's well established in ecological theory that isolated populations are most likely to experience a crash leading to localized extinction, largely due to a lack of genetic drift that keeps the gene pool diverse.
Each localized group of animals will have a minimal viable population size – essentially, the threshold where, if numbers drop below this point, there's no recovery. So it's easy to see why chlamydia-driven infertility is an even greater problem for koalas because of compounding pressures on the species.
Since Bamse received her revolutionary treatment in May, four more koalas have received the injection-implant vaccine and been released back into the wild. Bamse and one other individual were recaptured and assessed after a month and found to still be chlamydia-free.
Overall, more than 500 koalas have been given a single shot at Currumbin Wildlife Hospital and the Moggill Koala Rehabilitation Centre, including 30 young individuals.
However, this vaccine involved recapturing animals four weeks on from their initial shot in order to administer the booster injection. The new method greatly reduces the stress on these animals and the resources required to track and recapture such a large number of notoriously shy koalas.
And all signs point to a pleasing stabilization of the population in this region of southern Queensland.
In 2020, more than 70% of koalas from this one population that were treated at the hospital had chlamydia. Now, infection is down an estimated 75%, and the birth of 41 joeys and 13 grand-joeys has helped rebuild this koala community, which had previously been plagued by disease.
"We’ve seen such devastation from chlamydial disease in koalas in South East Queensland and New South Wales," Dr Payne adds. "It's absolutely critical the vaccine is rolled out en masse to at-risk populations to protect them.
"But the progress we’ve made is truly exciting, it gives us hope and allows us to think there is a way to save koalas."
Source: WWF Australia
Fact-checked by Mike McRae
