Study finds no evidence of chlamydia in koalas tested near Newcastle

Ryan Witt, a conservation scientist at the University of Newcastle, began studying the area after his attention was drawn to it by observations from Daryn McKenny, a Gamilaraay and Wiradjuri man who has tracked koalas there for more than seven years using motion-activated trail cameras. Since 2020, Dr Witt, Mr McKenny and their team have spent more than 250 nights surveying the 23,900-hectare reserve. "We fly thermal-imaging drones up and back, sort of like a lawnmower," Dr Witt said. "We do this across consecutive nights to account for whether a koala is there on a particular night or not."

In late 2025, the team confirmed 292 koalas; drone surveys and modelling in 2026 suggested a much larger population. "We think we have around 2,300 potential koalas in this landscape," Dr Witt said. "Given the fact that it is an urban population that has somehow survived on the edge of a major city, they seem to be thriving." Mr McKenny, who is the Aboriginal lead on the project, described walking on country as the key to spotting the animals: "It's about understanding the environment and the ecology from an Aboriginal lens."

After noticing an influx of koala joeys on footage through 2026, Dr Witt turned to the population's reproductive health. Researchers used drones to locate koalas before collecting fresh scats, which were preserved on dry ice and sent to laboratories at the University of the Sunshine Coast for genetic and disease testing. "We found 27 wild koalas without any evidence of chlamydia at the time of testing," Dr Witt said. "The disease is really prevalent in New South Wales populations, so it's pretty unusual." A review of wildlife rescue and clinical records from the Lower Hunter region between October 2022 and September 2026 also found no evidence of chlamydia among a further 27 koalas within 30 kilometres of the conservation area.

Mark Krockenberger, a specialist veterinary pathologist at the University of Sydney who has studied infectious diseases in koalas for 20 years, said only three NSW populations appeared to be chlamydia-free: in southern Sydney, Kanangra-Boyd National Park and Narrandera in the Riverina. He cautioned that the Newcastle pocket could not be declared disease-free with certainty: "You can't have 100 per cent say that the pocket near Newcastle is disease-free, but the genetic testing looks promising."

Dr Witt said the findings also pointed to low genetic diversity among the koalas, which may have been isolated from other populations for some time, potentially explaining the absence of disease. "Monitoring a larger landscape will give us a better understanding of the genetics outside of the core group," he said. Professor Krockenberger said evidence indicated the koalas were moving west of the Pacific Highway, which would put them at risk of contact with other populations carrying the disease, making the area "worthy of further study and conservation of koalas".

Dr Witt has submitted his research to the NSW government for consideration in the state's Draft Koala Conservation Strategy, recommending increased habitat protection in the Sugarloaf-Stockrington area, wildlife exclusion fencing and ongoing long-term monitoring, including longitudinal disease screening.