Newcastle Koalas May Be Free of Chlamydia, Offering Rare Hope for a Threatened Species

Daryn McKenny first saw a koala in the Sugarloaf-Stockrington State Conservation Area seven years ago. The protected bushland sits a 35-minute drive from Newcastle's CBD, and he now describes it as something close to his backyard. Since that first sighting he has put in hundreds of hours watching and tracking koalas there, using discreet motion-activated cameras strapped to trees.

McKenny is a Gamilaraay and Wiradjuri man, and he says walking on country is how you find koalas. He spent years learning where the food trees stand, then reading what the trees tell you through the tracks and scratchings left on them.

His observations led Ryan Witt, a conservation scientist at the University of Newcastle, to study the area. Since 2020, Witt and his team, with McKenny as Aboriginal lead, have spent more than 250 nights surveying koalas across 23,900 hectares. They survey on consecutive nights, Witt explained, to account for whether a koala happens to be present on any single night. In late 2025 the team confirmed 292 koalas in the area. Drone surveys and modelling done in 2026 point to a far larger population. "We think we have around 2,300 potential koalas in this landscape," Witt said.

Throughout 2026, footage showed an influx of joeys, which turned Witt's attention to the population's reproductive health. Chlamydia is a deadly threat to koalas, and according to Wildlife Health Australia (2023), infection rates in wild populations range from zero to nearly 90 per cent. To test for it, the researchers used drones to locate koalas and then collected fresh scats. The samples were kept on dry ice and sent to specialist laboratories at the University of the Sunshine Coast for genetic and disease testing.

The result: 27 wild koalas showed no evidence of chlamydia at the time of testing. A separate review of wildlife rescue and clinical records from the Lower Hunter region, covering October 2022 to September 2026, found no chlamydia in a further 27 koalas within 30 kilometres of the conservation area.

The findings come with a caveat. Witt said they also suggest low genetic diversity among the koalas. "We think they've been isolated from other populations for some time, which could be why they don't appear to have any disease," he said.

Mark Krockenberger, a specialist veterinary pathologist at the University of Sydney who has studied koala infectious diseases for 20 years, said only three other NSW populations appear to be chlamydia-free. Three years of sampling in southern Sydney, Kanangra-Boyd National Park and Narrandera in the Riverina detected no disease. He said continued monitoring would give a better picture of koala health at Sugarloaf-Stockrington, and he pointed to a risk: evidence suggests the koalas are pushing west of the Pacific Highway, which could bring them into contact with diseased populations. That, he said, makes the area worthy of further study and conservation.

Witt has submitted his research to the NSW government for consideration in its Draft Koala Conservation strategy, which sets out targeted actions to protect koalas and their habitat statewide. He recommends greater habitat protection in the area, wildlife exclusion fencing, and ongoing long-term monitoring, including longitudinal disease screening. Whether those measures are adopted will be the thing to watch.