The first time the Northern Territory GP and public health medical officer Dr John Boffa learned that the highly contagious bacterial infection diphtheria was spreading in his community was in late March – several months after the outbreak first began.

“By the time we became aware of it, it had been grumbling along for some time,” says Boffa, who is chief medical officer with the Central Australian Aboriginal Congress Aboriginal Corporation, a community-controlled primary healthcare service in Alice Springs.

At that point, Northern Territory Health was aware of 37 cases of cutaneous (skin) diphtheria, which had been emerging since May 2025, and four cases of the more serious and potentially deadly respiratory diphtheria (two in Darwin and two in Alice Springs), with all of those cases diagnosed in March.

“I quickly then learned about all the cases that had been in Darwin since last year, and at that point our case here in Alice Springs was not linked to the Darwin outbreak, or other cases,” he says. “Then it was obvious it was everywhere, because if you’ve got unlinked cases, it’s all around us. So you need a response everywhere.”

Congress kicked into action, but “once we started going out to town camps to immunise, we realised there wasn’t enough information out there in the community either”, Boffa says. This included information about “the severity of diphtheria”, he says, but also about how to get vaccinated or when to get a booster shot, which for health workers and Indigenous people is recommended every five years.

Initially, there was also a struggle to get enough vaccine supply, Boffa adds. Meanwhile, by May, between 15 and 20 new cases were being diagnosed each week. There is one laboratory at Royal Darwin hospital testing for diphtheria, Boffa says, with results taking up to one week to come back.

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“We finally got over that vaccine supply issue by the end of last week,” he says. “So we had enough vaccine, that wasn’t a problem. We also realised very quickly we didn’t have a major vaccine hesitancy issue, and once people were informed they were happy to get vaccinated.

“We were actually impeded by workforce. It’s not like you can sit in the clinic and wait for everyone to come to you, that won’t happen in remote communities. That’s why we need outreach workforce, and surge workforce capacity. We need to go out door to door, to get the message and vaccine out.

“We went out house by house, and also engaged community leaders to spread the message as well.”

Controlling the spread

There are now more than 230 diphtheria cases as part of the outbreak. This includes at least 85 cases in WA, seven confirmed cases in the APY Lands in South Australia, and several in Queensland. Up to one-third of cases have been hospitalised with respiratory diphtheria. Most cases have been in Indigenous adults, highlighting ongoing issues with overcrowded housing and poor living conditions in remote communities.

Northern Territory Health says 50 patients have been hospitalised with diphtheria and possible other health conditions since January in the territory. Four were admitted to intensive care. Prior to the outbreak, Australian Institute of Health and Welfare data shows there were six or fewer hospitalisations each year since 1999.

Brenda Garstone is the chief executive officer of Yura Yungi Medical Service Aboriginal Corporation in Halls Creek, a community of 4,000 people on the edge of the Great Sandy Desert, some 2,800km north of Perth. Housing is overcrowded and families regularly travel in from surrounding communities for supplies and access to essential services.

Most of the confirmed cases in WA are in the Kimberley region, with a number in Halls Creek, but Garstone believes the real number may be higher. More than a third of recorded cases are in children and teenagers.

“We’ve got a small community, so it’s inevitable that it’s probably going to spread a bit more,” she says.

The Jaru woman says their small health service is already stretched with the pressure of delivering culturally and linguistically appropriate care and public health messaging, in a region where 43% of Indigenous households speak traditional languages at home. Contact tracing, and uncertainty over whether Covid-era funding for a dedicated vaccination officer will continue, is adding to that pressure.

“I think it’s about raising awareness and being equipped and ready and supported to really manage and prevent this from becoming a real serious outbreak, but I mean, maybe we’ve left it too late? I don’t know,” she says.

“It was eradicated for so long, and it’s been so many decades since it was around that people don’t really know what to look for. We’ve never had it before, we’ve never experienced it before, so we don’t know what it looks like.”

In Queensland’s Yarrabah community, medical services are on standby. A public information campaign is under way to raise vaccination rates, previously over 95%, which had dropped slightly post-Covid.

“Our rates have started to climb back up to where we need them to be, but it’s still a pretty uphill battle,” says Dr Jason King, a Yued Noongar man and director of clinical services at Gurriny Yealamucka Health Service.

“We’re plugged into the sort of regional public health response with Queensland Health, and our own public health team which has grown out of the Covid experience. So we’ve been taking control of more public health measures and approaches in the community.”

Delayed response

In April, Boffa said a partnership of organisations, including the Australian Centre for Disease Control and the chief health officer, made an application to the federal government for funding to help address the outbreak.

When that requested support had still not come by 16 May, and when there was still a lack of information going out to communities, Boffa became frustrated, telling the ABC that the Northern Territory had recorded its first diphtheria death in more than a decade, an adult in a remote area.

The cause of death is yet to be confirmed by the coroner, and NT Health is awaiting results from an autopsy report to establish whether the man died with, or from, diphtheria.

“I felt like everything was taking too long,” Boffa says.

“We had an application in for funding, we weren’t hearing when that was going to get supported. One of the lessons we’ve learned with communicable disease is you’ve got to go hard, go early. Once you let the genie out of the bottle, it’s very hard to put the genie back in and the lid back on.

On Thursday, the federal government announced a $7.2m package to address the outbreak, with a significant portion of that going towards a surge workforce, and to procure additional vaccines and antibiotics.

“It’s actually more generous than what we originally asked for, which is fantastic,” Boffa says. “It is going to make a big difference.”

He says he did not blame the government for the time it took to respond, but questions whether the application for funding should have been made sooner.

He believes part of the issue is that the early cases were cutaneous diphtheria, which is rarely life-threatening and does not usually cause severe illness, creating less urgency. It nonetheless requires prompt treatment with antibiotics, since it can cause chronic ulcers on the skin, and lead to secondary infections.

Transmission from cutaneous lesions can cause respiratory disease in other people.

Ongoing education campaigns about booster shots for adults will be important, Boffa says, given vaccination rates for Aboriginal and Torres Strait Islander five-year-olds are at 94.33%.

“I think if we get boosted rates up to where they need to be, and once we’re able to more effectively contact-trace and treat with antibiotics, then we should start to see this outbreak dissipate and go away,” he says.

“I think, though, we’ve got to get better at this … Particularly when it’s in Aboriginal communities affected, the community-controlled sector needs to be engaged right up front.”