Scientists Trying To Save Chlamydia-Stricken Koalas With Vaccine

(Photo by Bernd Lauter / AFP) (Photo by BERND LAUTER/AFP via Getty Images)

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Scientists in Australia are undertaking an enormous field trial by vaccinating koalas in the wild against chlamydia, a disease that has dwindled the numbers of the beloved marsupials.

Facing habitat destruction from wildfires and land clearing, koalas in Australia are already considered endangered by Australia’s federal government. In the past decade, however, chlamydia has ravaged through the koala population, leading researchers to offer up the grim prognosis that by 2050, koalas could be totally extinct, as reported by the Associated Press.

“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,” Samuel Phillips, a microbiologist at the University of the Sunshine Coast who helped to develop the vaccine, told the outlet.

Unlike humans and other animals, koalas cannot be treated for chlamydia with antibiotics as the “complex” microbes in their stomachs neutralize the effects of certain medicines — antibiotics included, Mathew Crowther, a conservation biologist at the University of Sydney told the outlet. (RELATED: Australia Employs Terminator Machines To Kill Stray Cats)

Scientists believe that the origins of chlamydia in koalas began after exposure to feces from infected sheep and cattle, the AP reported. After that, the disease was spread sexually and/or passed from mother to offspring. In one population of koalas in New South Wales, the amount infected rose from 10% in 2008 to 80% in 2023, the outlet reported.

“It’s been devastating — there’s very, very low fertility,” Crowther said. “You hardly see any babies.”

A necropsy performed on one koala with advanced chlamydia that was euthanized revealed “ovaries completely encased in cysts” and “intestines full of hard lumps of food, evidence that she couldn’t properly digest food,” Rebecca Johnson, chief scientist at the Smithsonian National Museum of Natural History in Washington, D.C., told the outlet. Johnson previously led the Koala Genome Consortium in Australia.

“She was obviously infertile and in pain,” Johnson added.

The decision to allow the vaccination trial was approved by multiple government bodies in Australia. By vaccinating, scientists are hoping the risk of disturbing the animals is balanced out by stopping the devastating disease from continuing to spread through the koala population, the AP reported.

“Vaccination is an incredibly resource-intensive thing to do. Koalas live high up in trees. But because the effects of chlamydia are so debilitating, I think it’s totally worth it,” Johnson stated, according to the AP.

In order to administer the vaccinations, scientists coax the animals down from their high perches with offers of food where they eventually wander into traps. After a check-up, the animals are then given a dose of anesthesia and then the vaccine. Scientists then observe the animals for 24-hours before releasing them back into the wild, the outlet stated.

“Vaccination for wildlife is certainly not routine yet,” Jacob Negrey, a biologist at Wake Forest University School of Medicine, told the AP. “But whether it should be used more often is a fundamental question that conservation biologists are really wrangling with right now.”