“Diphtheria is caused by a bacteria and is a serious infectious disease that affects the throat and skin. It can become severe and life threatening in some cases and is spread through close contact with infected person through coughing and sneezing or skin sores. The Diphtheria outbreak in the Northern Territory (134 cases), WA (80 cases), SA (6 cases) and Queensland (5 cases) is of significant concern, is the worst seen in Australia in recent times and this outbreak was identified since December 2025. It is targeting Aboriginal communities of the Kimberley region with some cases in the Goldfields and Pilbara in WA.  For over 50 years Australia had no cases of Diphtheria so this resurgence highlights a reduction in vaccination rates and boosters. We need all of the population in the Northern Territory and Central Australia and WA in the impacted communities to be vaccinated or receive a booster with urgency. We need to expand vaccinations under the National Immunisation Program where childhood vaccination is completely free under the scheme, but with the adults, it's still not the case. A concerted effort must be made by the Federal and State Health departments and use Aboriginal health workers for a community education program. My mother was infected with Diphtheria as a child over 80 years ago in Mumbai, India, so this outbreak infecting communities bring home those memories.”

"Diphtheria is a rare but dangerous infection caused by bacteria called Corynebacterium diphtheriae.

It can affect the skin, causing sores or ulcers, affect the throat, causing pain and making it hard to breathe, and in some cases, it can damage the heart and nerves.

These vaccines have been used safely for many years and are very effective. They work by training the immune system to recognise and block the diphtheria toxin that causes illness.

To keep diseases like diphtheria under control, we need very high vaccination rates across the community. If coverage falls, we start to see gaps where outbreaks can occur.

Vaccination protects not just individuals, but the whole community. Keeping vaccination rates high at all ages is the best way to protect people from deadly diseases like diphtheria.”

"Diphtheria does not return to a population by chance. It returns where vaccination coverage has slipped and where living conditions allow it to spread. In this outbreak, almost all cases are in Aboriginal Australians, with many occurring in remote and very remote communities. Most are skin infections spread through close physical contact, the pattern you would expect in overcrowded housing. Cutaneous (skin infection) cases are typically less severe, but the bacteria they carry can spread to unvaccinated contacts.

Nationally, childhood vaccination coverage at 24 months fell below 90% in 2024 for the first time since 2016. That weakens community protection across Australia, not just in Aboriginal communities.

Australian guidance recommends adult diphtheria boosters at 50 and 65 if more than 10 years since last dose, with a tighter five-year interval for at-risk groups. Adult booster coverage, however, is not routinely monitored the way childhood coverage is. We do not know what we do not measure.

People who are due for a booster should get one. But this outbreak should not be framed solely as an Aboriginal health issue. It is also a warning about gaps in vaccination coverage, overcrowded housing, and infectious disease surveillance that have been building nationally for years."

"Australia is currently in the midst of our worst diphtheria outbreak in decades. This outbreak is significant because it’s affecting a broad swathe of First Nations communities across multiple Australian states and territories, with high case numbers and one likely death to date.

Although health outcomes in First Nations people have improved in recent years, they still face higher rates of acute and chronic diseases than non-indigenous Australians. For example, Australia has only just eradicated trachoma, a bacterial infectious disease that disproportionately affected indigenous Australians – sadly, it took a century to achieve this outcome.

Diphtheria, which is a notifiable disease in Australia, is caused by two pathogenic bacteria, Corynebacterium diphtheriae and C. ulcerans. These highly contagious microorganisms infect the skin and upper respiratory tract, and can produce diphtheria toxin. Early symptoms include a mild fever, sore throat, and swollen neck glands, or skin sores with local swelling and tissue damage in cutaneous cases. Symptoms can worsen as the bacterium blocks the airways, and the toxin can spread via blood, causing heart failure and paralysis.

This ancient disease can be prevented by vaccination. Treatment comprises intravenous diphtheria antitoxin administration. Less severe cases can be treated with penicillin, macrolide, or tetracycline antibiotics."

"The spread of diphtheria from the Northern Territory into South Australia and Queensland is deeply alarming and represents a crisis that should not be happening in 2026. This is a vaccine-preventable disease. Every case represents a failure somewhere in our public health system.

Over 98% of cases are affecting Indigenous Australians, with the vast majority occurring in remote and very remote communities, populations that already face significant barriers to healthcare access. We must be honest, this is not simply a matter of individual vaccine hesitancy. It reflects decades of under-investment in culturally appropriate, community-led health infrastructure.

That said, vaccine hesitancy accelerated through the COVID-19 pandemic, combined with lagging booster uptake among adolescents and adults, has created dangerous gaps in herd immunity. Misinformation costs lives. We are seeing that in real time.

From an infection prevention and control perspective, contact tracing, isolation of confirmed cases, and urgent vaccination of high-risk contacts must be prioritised immediately. Healthcare workers across all affected jurisdictions must check their own booster status now.

The diphtheria vaccine is safe and effective. The science is unambiguous. What is needed is political will, adequate resourcing, and community trust, built through partnership, not paternalism."

"Diphtheria is a serious and potentially fatal infection, especially in infants who get respiratory diphtheria. Diphtheria can cause a thick membrane to form in the throat that blocks off the windpipes and obstructs breathing. It is concerning to see a resurgence of what was a rare disease prior to 2020. 

This outbreak is largely locally acquired cases, mostly in Aboriginal communities, in contrast to the pre-2020 epidemiology, when it was mainly a rare, travel-imported disease. Diphtheria in Australia started to increase in October 2025, with another big jump in February this year, with more cases in 2026 to date than any single year in the past quarter century. This is an unprecedented epidemic, with most of it diphtheria skin infection, and about a quarter being respiratory diphtheria.

We are fortunate to have a CDC to coordinate the response across the affected states. Data released by the ACDC in April showed that almost 80% of respiratory diphtheria cases had at least 3 doses of vaccine, and 53.8% of those with skin diphtheria had been vaccinated. This is quite worrying, as a large proportion of cases are vaccinated with the primary course. The vaccine does wane, and boosters are needed. The occurrence of diphtheria in vaccinated people may reflect partial vaccination, missed booster doses, or weakened immunity in fully vaccinated people. The role of vaccine hesitancy, misinformation, trust, and other infections affecting the respiratory tract, needs to be explored. 

Australia has always had extremely high rates of childhood vaccination. However, from record high levels of childhood vaccination prior to the COVID-19 pandemic, we have seen vaccination rates for the combined diphtheria, whooping cough and tetanus shot declining in Australia since around 2020–2021. Vaccination rates may be lower in remote communities. In fact, all vaccination rates have been falling, not just in Australia and globally, for other vaccines like measles, and even the influenza vaccine for older adults. This is likely due to the rise in vaccine misinformation and pushback against vaccines after the COVID-19 pandemic.  We urgently need tools to monitor and detect health misinformation that can help us intervene early with health promotion to improve vaccine confidence.

Historically, large diphtheria epidemics can occur when vaccination programs get disrupted - when the Soviet Union fell in 1991, over 140,000 cases and over 5000 deaths resulted, in what was the largest epidemic since routine infant vaccination was the norm."

"Diphtheria is an acute infection of the upper respiratory tract caused by the bacterium Corynebacterium diphtheriae. It presents with sore throat, fever, malaise, and lymphadenopathy [swollen or enlarged lymph nodes]. A key clinical feature is the formation of a thick, greyish pseudomembrane over the tonsils, pharynx, or nasal passages, which can bleed if disturbed and may lead to airway obstruction in severe cases. The bacterium is transmitted through respiratory droplets or close personal contact, particularly in overcrowded environments with low vaccination coverage.

Disease severity is mainly due to diphtheria toxin, which can spread systemically and cause serious complications, including myocarditis [swelling of the heart], arrhythmias [irregular heart rhythm], heart failure, and peripheral neuropathy [damage to the peripheral nerves]. Prompt diagnosis and treatment are essential to reduce morbidity and mortality. Management includes administration of diphtheria antitoxin to neutralise circulating toxin, along with antibiotics such as erythromycin or penicillin to eradicate the organism. Public health measures, including isolation, contact tracing, prophylactic antibiotics for close contacts, and vaccination, are critical to control outbreaks and restore herd immunity. 

Cutaneous diphtheria occurs when the organism infects broken skin, such as cuts, ulcers, or insect bites. It produces shallow, chronic, non-healing ulcers often covered with a grey membrane or crust. Although less severe in appearance than respiratory disease, these lesions can still harbour toxigenic strains and act as an important reservoir for transmission, particularly in low-resource or crowded settings."

“Reports that the Northern Territory diphtheria outbreak has now spread into Western Australia, Queensland and South Australia are deeply concerning. This is no longer an isolated outbreak, and it highlights how quickly vaccine-preventable diseases can re-emerge when there are immunity gaps.

Diphtheria remains rare in Australia because vaccination works. But this outbreak is a reminder that rare does not mean impossible, and that protection needs to be maintained through timely boosters for adolescents and adults.

The most important message is that diphtheria is preventable. Vaccination and boosters remain our best protection against severe disease, hospitalisation and death, and they are especially urgent in communities where people face barriers to healthcare.

The fact that this outbreak is affecting Aboriginal communities points to the need for a rapid and culturally safe public health response. That means working with Aboriginal community-controlled health services, trusted local leaders and frontline workers to make testing, treatment and vaccination as accessible as possible.

Getting tested, treated and vaccinated protects individuals, families and the wider community.”