Australia is experiencing its largest diphtheria outbreak in decades, with cases spreading from the Northern Territory into Western Australia, South Australia, and Queensland. As of the latest data, there are 133 cases in the Northern Territory, 79 in Western Australia, six in South Australia, and up to five in Queensland, according to the National Notifiable Disease Surveillance System.
Health Minister Mark Butler described the outbreak as serious, noting that vaccines are being rushed to affected communities. “There’s no question this is serious. It’s serious in the NT. It’s spreading across other parts of the Top End. It’s crept below the South Australian border into the APY Lands,” he told ABC Radio National.
The outbreak, which began in late 2025 and was declared in March, has been driven by falling vaccination rates since the pandemic and missed booster shots among adults. Routine childhood immunisation coverage dropped to its lowest level in five years in 2025. The Australian immunisation handbook recommends diphtheria vaccine for infants, children, adolescents, and routine boosters for adults, especially pregnant women.
Dr John Boffa, public health medical officer at the Central Australian Aboriginal Health Congress, said about one-third of cases are respiratory diphtheria, which can be life-threatening. “We’re seeing about 20 new diphtheria cases a week. That hasn’t slowed down yet,” he said, adding that roughly a third of new cases require hospitalisation, straining the NT’s hospital system.
One suspected death—the first diphtheria fatality in Australia since 2018—is under investigation. Butler stated it is “95% certain” that the person died from diphtheria, with a known complication of heart inflammation. Diphtheria is treated with antibiotics, and respiratory cases may require antitoxin.
