A wild koala becomes the first to get the two-dose chlamydia vaccine

Bamse received a new injection-plus-implant chlamydia vaccine, part of a Queensland effort that has cut infection sharply.

An 18-month-old female koala named Bamse became the first to receive an approved chlamydia vaccine in a new two-dose format. Captured from a wild population in Burleigh, Queensland, and treated at Currumbin Wildlife Hospital, she was given the vaccine by senior vet Dr Michael Pyne. The vaccine was approved for Australia's koala population about ten months earlier.

The new format combines an injection with a biodegradable implant, created by scientists at Queensland University of Technology, that breaks down over 30 days to release a second dose. Bamse was fitted with a GPS collar for six months of monitoring. Chlamydia is a severe threat to the species: an estimated 50% of remaining koalas are infected, rising to 90% in some populations, and Chlamydia pecorum can cause blindness and infertility.

The stakes are conservation. The IUCN Red List classifies the koala as vulnerable with decreasing numbers, so protecting breeding-age animals directly supports the survival of a threatened species and the wider ecosystem it belongs to. In one southern Queensland population, chlamydia was found in over 70% of treated koalas in 2020, and infection is now down an estimated 75%, with 41 joeys and 13 grand-joeys born.

Since Bamse's May treatment, four more koalas received the injection-implant vaccine and were released, and Bamse and one other were recaptured after a month and found chlamydia-free. More than 500 koalas have received a single shot. Efficacy monitoring is ongoing, and the reduction and population figures are estimates for one region.

Source: New Atlas