Australia faces biggest diphtheria outbreak since 1991

Health officials around the country have warned cases of diphtheria could rise, as Australia experiences the biggest outbreak of the disease since national records began in 1991.

About 220 people across Australia have now tested positive to diphtheria, with 133 cases in the Northern Territory, 82 in Western Australia, six in South Australia and less than five in Queensland.

The Northern Territory recently recorded the first suspected death from diphtheria in Australia in almost a decade.

According to a report from the Australian Centre for Disease Control (CDC) released last week, 94 per cent of cases identified since January 1 have been Aboriginal and Torres strait Islander people.

The report also said 25 per cent of people who had tested positive for diphtheria had been hospitalised.

Manjit Sekhon, chief executive of Mount Isa-based Indigenous primary health care provider Gidgee Healing, said Queensland was preparing for case numbers to rise.

"Far North Queensland should be worried because of the geographical proximity to the affected areas," she said.

"We do know that the families and mob, they sort of cross over the border quite often with their families and communities.

How did we get here?

A CDC spokesperson said the strain of diphtheria circulating appeared to have emerged recently, although it may have been in Australia for some months.

"We are still seeking to fully understand the factors driving the current outbreak," the spokesperson said.

"Sporadic cases are not unusual, but we don't typically see diphtheria spread like this in Australia."

Burnett Institute head of immunisation and health system strengthening, Milena Dalton, said the current situation highlighted "health system gaps" in providing remote communities with access to vaccinations.

"It's really important, I think, in these outbreaks to avoid the blame game," Dr Dalton said.

Dr Dalton said booster diphtheria vaccinations were recommended every five years for people living in or visiting high-risk communities.

Previously, advice around high-risk communities has typically been reserved for tourists travelling to developing countries, but the recent outbreak means it now applies to some parts of Australia.

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Dr Dalton said moving forward, the focus needed to be on testing and treating people quickly and employing contact tracing to stop further spread.

"The government … really needs to drive the response across all of those areas," she said.

What is diphtheria?

Diphtheria is a life-threatening and highly contagious bacterial infection that is vaccine-preventable and can be treated with antibiotics.

There are two strains of diphtheria that have been identified in Australia: respiratory and cutaneous.

Respiratory diphtheria can affect the nose, throat and airways, while cutaneous diphtheria can affect the skin.

The respiratory strain spreads through droplets from coughing or sneezing, or direct contact with infected wounds.

Even with treatment, one in 10 people with respiratory symptoms die, according to the Australian CDC.

Historically, diphtheria was a leading cause of childhood death globally and, according to the National Centre for Immunisation Research and Surveillance Australia, more than 4,000 Australians died from the disease between 1926 and 1935.

But vaccination started in Australia in the 1930s, and since the 1950s the disease has been considered largely eliminated.

According to the Australian CDC, the largest previous outbreak the country has experienced since 1991 was in 2022 when 25 cases were recorded in Queensland.

State leaders respond to diphtheria

With 82 cases recorded in WA, the state's Health Minister Meredith Hammat said while there was no cause for alarm, the reappearance of the disease underlined the importance of vaccination.

"There is a really important message here about making sure that your vaccinations are up to date," Ms Hammat said.

Ms Hammat said contact tracing was underway across the state and booster vaccines were being provided to residents in the Kimberley region.

While only six cases had been recorded in South Australia, the state's Health Minister Blair Boyer said the outbreak needed to be taken seriously.

"If you're travelling into remote communities, there's a lot of very good information online about the risk and what you can do," he said.

"You can go to your GP if you think you are in one of those vulnerable cohorts and you can ask for the diphtheria vaccination and it can be administered to you."

With fewer than five cases recorded, the Queensland government has made the diphtheria-toxoid vaccines free for First Nations people 20 years and older, and Aboriginal health services across the state are actively promoting the vaccine.

Gidgee Healing is rolling out booster vaccines and hygiene messaging throughout north-west Queensland communities.

Dr Sekhon said Indigenous communities across the region were at higher risk of contracting the disease.

"The risk of people getting the infection and the risk of then this infection being a serious, even life-threatening infection, is significantly higher in Aboriginal and Torres Strait Islander populations of our region," she said.

"You don't wait for an outbreak to really become critical … we need to really take these outbreaks seriously as a population and act on it.

"That can stand us in good stead to get over this reasonably early before it really reaches catastrophic levels."

Federal Health Minister Mark Butler said the federal government was working on a support package primarily aimed at boosting vaccination rates.

He said the package would include more vaccines and a surge workforce.