Australia is experiencing its most significant diphtheria outbreak in decades, with the serious bacterial infection spreading from the Northern Territory into Queensland, South Australia, and Western Australia. Health Minister Mark Butler has expressed deep concern, calling it 'the biggest diphtheria outbreak we've seen, certainly for decades.'
Outbreak Details
The outbreak, which began in late 2025, has resulted in 133 cases in the Northern Territory, 79 in Western Australia, six in South Australia, and up to five in Queensland. Cases include both cutaneous (skin) and respiratory forms of the disease. Prior to the COVID-19 pandemic, diphtheria was rare in Australia, with most cases imported from overseas. However, since 2020, small clusters have emerged in northern Australia, predominantly affecting Indigenous communities.
Government Response
Minister Butler stated that the federal government is collaborating with the Northern Territory government and Aboriginal-controlled health services to expedite vaccine distribution. 'There's no question this is serious,' he told ABC Radio National. 'We're working very closely with the NT government, but also with the Aboriginal-controlled sector.'
Vaccination Challenges
Falling vaccination rates since the pandemic have contributed to the outbreak. Routine childhood immunisation coverage dropped to its lowest level in five years in 2025, with only about 90% of two-year-olds vaccinated, well below the 95% target needed for herd immunity. Booster shots for adolescents and adults are also crucial, as immunity wanes over time. Dr. John Boffa, a public health medical officer in Alice Springs, noted that one-third of new cases are respiratory diphtheria, and about one-third of all cases require hospitalisation.
Fatality and Concerns
There has been one suspected death linked to the outbreak, which would be the first diphtheria death in Australia since 2018. Dr. Boffa stated it is '95% certain' the adult died from diphtheria, developing a known complication of heart inflammation. Professor Robert Booy, an infectious diseases paediatrician, emphasised that overcrowded housing facilitates transmission, making rapid vaccination access critical.
Dr. Milena Dalton from the Burnet Institute warned that the outbreak 'highlights how quickly vaccine-preventable diseases can re-emerge when there are immunity gaps.' She stressed the importance of timely boosters for adolescents and adults to maintain protection.
