Australia is experiencing its worst diphtheria outbreak in decades, with more than 220 confirmed cases of the bacterial infection recorded across the country.
Most cases have been reported in the Northern Territory, though infections have spread to Western Australia, South Australia and Queensland. One death is suspected to be linked to the outbreak, but the Northern Territory government is still investigating the cause.
Almost all cases have affected Indigenous Australians.
Federal Health Minister Mark Butler has described the situation as “very concerning”.
“To put that in context, we have been recording case numbers nationally for about 35 years, and this, by a very big distance, is the biggest outbreak of diphtheria we have ever seen,” he said. “It is about 30 times the average number of diphtheria cases that we’ve seen over the last five years or so.”
The Albanese Government today announced a $7.2 million funding package to help contain the outbreak.
What is diphtheria?
Diphtheria is a serious bacterial infection that can affect the nose, throat, airways or skin.
There are two main forms: respiratory diphtheria, which affects the throat and breathing passages, and cutaneous diphtheria, which affects the skin.
In severe cases, respiratory diphtheria can block the airways, while toxins released by the bacteria can lead to serious complications, including heart and nerve damage.
What are the symptoms?
Symptoms usually develop between two and five days after infection.
Respiratory diphtheria symptoms can include sore throat, fever or chills, swollen glands in the neck, difficulty breathing and a thick grey coating over the throat or tonsils.
Skin diphtheria can cause painful or inflamed skin sores and slow-healing ulcers that may develop a grey membrane.
Dr John Boffa, public health medical officer at the Central Australian Aboriginal Health Congress, said around one-third of cases in the current outbreak have involved respiratory diphtheria.
“Skin diphtheria can lead to respiratory diphtheria in other people, and so it’s all concerning,” he said.
How does diphtheria spread?
Diphtheria spreads through respiratory droplets when an infected person coughs or sneezes, or through close contact with infected skin sores.
Dr Boffa urged anyone with symptoms to seek medical advice.
“Anyone with a sore throat at this stage needs to go to their clinic,” he said.
Why are cases increasing?
Diphtheria is now considered rare in Australia after widespread vaccination programs began in the 1930s.
However, health experts say falling childhood vaccination rates and missed booster shots among adults are contributing to the current outbreak.
Routine childhood immunisation rates dropped to their lowest level in five years in 2025, while many adults may not realise they need booster vaccinations later in life.
Should you get a booster?
Health authorities say vaccination remains the best protection against diphtheria and are encouraging people to check whether they are up to date.
Media experts have encouraged Australians to ensure they have had the DTP vaccination (for diphtheria, tetanus and whooping cough) in the last 10 years, or the last five years for those living in outbreak-affected areas.
Booster shots are being encouraged for some adolescents and adults over 50, while people at higher risk may need boosters more frequently.
If you’re unsure whether you or your family are up to date, speak to your GP, pharmacist or healthcare provider.
