Australia is grappling with its most severe diphtheria outbreak in decades as the bacterial infection continues to spread, predominantly through the Northern Territory. Health authorities report over 220 cases, with almost all involving Indigenous Australians.
Outbreak Details
The country's top medical body is urging all Australians to ensure they are fully vaccinated against diphtheria following a resurgence of the Victorian-era disease. Most cases have been reported in the Northern Territory, Western Australia, South Australia, and Queensland.
Diphtheria, which can cause swollen glands, breathing problems, and fever, primarily affects children. It was considered nearly eradicated after a vaccination rollout that began in the 1930s. The current outbreak is attributed to a decline in vaccination rates. Cases began rising in 2025, prompting the Northern Territory Centre for Disease Control to declare an outbreak in March.
Impact on Indigenous Communities
Almost all cases involve Indigenous Australians, pushing health authorities to collaborate with Aboriginal agencies to improve immunisation rates. Health authorities are awaiting the outcome of an investigation into a suspected diphtheria death, which could be the first fatality from the disease in nearly a decade.
Federal Health Minister Mark Butler stated, "We've been recording case numbers nationally for about 35 years and this, by a very big distance, is the biggest outbreak of diphtheria we've ever seen." He announced that the government is drafting a support package as childhood vaccination rates, including for diphtheria, fell to a five-year low in 2025. "More vaccines, a surge workforce is part of the package we'll be finalising over the course of today, working closely with the Northern Territory government and with the Aboriginal-controlled sector, because this is overwhelmingly an outbreak being experienced by Indigenous Australians in Northern Territory," Mr Butler said.
Hospitalisations and Health System Pressure
The majority of cases are respiratory diphtheria, which are "far more serious in terms of their potential." About 25 per cent of cases have required hospitalisation, placing pressure on hospital systems in the Northern Territory. "So this is obviously a deep concern for people who are exposed to this disease, but it is also starting to place pressure on hospital systems in the Northern Territory as well," the minister added.
According to the National Notifiable Disease Surveillance System, at least 133 cases have been recorded in the Northern Territory, 79 in Western Australia, six in South Australia, and five in Queensland.
Expert Commentary
Immunisation expert Milena Dalton told the AAP news agency that the outbreak highlights how quickly vaccine-preventable diseases can re-emerge due to gaps in immunisation. "Although diphtheria remains rare in Australia this outbreak shows it hasn't disappeared," she said.
Symptoms and Transmission
Diphtheria typically spreads through contact with coughs and sneezes of infected individuals or through shared items like cups, cutlery, clothing, or bedding. Symptoms usually appear two to five days after infection and may include a thick grey-white coating covering the back of the throat, nose, and tongue, along with fever, sore throat, swollen neck glands, and difficulty swallowing or breathing. If cutaneous diphtheria is contracted, affecting the skin, patients may develop pus-filled blisters on their legs, feet, or hands, along with large ulcers surrounded by red, sore-looking skin.
