Koala numbers are plunging in the wild, and at least part of the problem is a chlamydia epidemic among the marsupials. As a result, wildlife authorities in Australia have begun an unusual clinical trial—they're inoculating about 200 koalas with a new vaccine designed to ward off the disease, reports New Scientist. The vaccinated koalas will be microchipped and released back into the wild, and researchers will track how many turn up with chlamydia in the next year when compared to an unvaccinated control group, per CNN.
"It is a cruel disease that causes debilitating conjunctivitis, bladder infections, and at times, infertility," says veterinarian Amber Gillett of the Australia Zoo Wildlife Hospital, lead researcher. Blindness also has been reported. The disease is typically spread through sexual contact, though mothers can pass it on to their infants. Smaller studies have raised hopes of turning around the koala population numbers. If all goes well, it's possible the research could even lead to a similar vaccine for people. "I think this trial will be closely watched by the human chlamydia vaccine world," says Peter Timms of the University of the Sunshine Coast in Queensland. (Wildfires also have taken a big toll on the koala population.)