Chlamydia, a sexually transmitted disease also found in humans, has become widespread among Australian koalas, affecting half the animals in some areas.
“It is a serious disease that causes debilitating conjunctivitis, bladder infections and sometimes infertility,” Australian Zoo Hospital veterinarian and research coordinator Amber Gillette said in a statement on Friday.
The bacterial disease, which can be transmitted from mothers to newborns, can also cause blindness, researchers say.
Each koala will receive a dose of the vaccine and a microchip before being released into the wild.
“While this vaccination directly benefits each animal, the trial will also focus on the protection afforded by the vaccination,” said Peter Timms, a professor of microbiology at the University of Costa do Sol, who is leading the trial.
Although chlamydia can be treated with antibiotics in many cases, the researchers hope the vaccine will help improve the animals’ survival and reproduction.
Estimates of the number of koalas vary, as they are difficult to count in the wild. A 2016 study from the University of Queensland estimated that there are about 330,000 koalas left in Australia.
A study by the World Wildlife Fund estimated that more than 60,000 koalas were killed, injured or affected by devastating wildfires in Australia in 2019 and early 2020.