Australia faces 'biggest diphtheria outbreak' in decades, cases across Western Australia, Queensland, South Australia

Diphtheria is a rare but serious bacterial infection that usually affects the mucous membranes of the nose and throat. Tn advanced stages, the condition can damage the heart, kidneys and nervous system.

The Australian health minister, Mark Butler, has expressed concerns about the biggest diphtheria outbreak the country has witnessed since 1991, spreading through the Northern Territory (NT) and bordering states. 

Before the Covid-19 pandemic, most Australian cases came from overseas, according to a Guardian report. And a high proportion of these cases were cutaneous diphtheria. But since 2020, small clusters of cases have been reported in multiple areas of northern Australia, including both cutaneous and respiratory cases. 

The most recent outbreak began in late 2025 and was declared an outbreak in March by the Northern Territory Centre for Disease Control. 

Diphtheria is a rare but serious bacterial infection that usually affects the mucous membranes of the nose and throat. Diphtheria can be treated with medications. But in advanced stages, diphtheria can damage the heart, kidneys and nervous system. Even with treatment, diphtheria can be deadly, especially in children. The symptoms may include fever, chills, tiredness, sore throat, nasal discharge, swollen glands in the neck, and breathing difficulties. Meanwhile, cutaneous diphtheria can affect the skin, causing pain, redness and swelling similar to other bacterial skin infections. 

The Australian Broadcasting Corporation (ABC) said, “About 220 people across Australia have tested positive, with 133 cases in the Northern Territory, 82 in Western Australia, six in South Australia, and less than five in Queensland. The Northern Territory also recently recorded the first suspected death due to diphtheria; it is the first death reported in almost a decade.

Butler told ABC Radio National on Tuesday, “There is no question this is serious.” “It is serious in the NT. It is spreading across other parts of the Top End. It has crept below the South Australian border into the APY Lands. So we are working very closely with the NT government, but also with the Aboriginal-controlled sector.”

The falling vaccination rates since Covid, combined with people missing booster shots as adults, have been attributed to causing a spread. Reports said the routine childhood immunisation coverage fell to its lowest level in five years in 2025. The Australian immunisation handbook recommends the diphtheria vaccine for infants, children and adolescents, and routine booster vaccination in adults.