Jun 3

Diphtheria Outbreak in Australia 2026

What Aged Care Teams Must Do Now: Recognising Symptoms, Protecting Vulnerable Residents, and Reviewing Vaccination in Your Facility

Australia is experiencing its worst diphtheria outbreak since 1991, with the country's first fatality in nearly a decade confirmed in 2026. This blog explains what aged care teams need to know: how diphtheria spreads, why older residents face the highest risk, what symptoms to watch for, and the immediate steps your facility should take to protect residents and staff.

A male patient died at Royal Darwin Hospital in April 2026, and autopsy results confirmed diphtheria as the cause. This is the first fatality from the disease since 2018. With more than 245 cases recorded in Australia this year alone, the country is in the grip of its worst diphtheria outbreak since national records began in 1991. The Chief Medical Officer has declared it a Communicable Disease Incident of National Significance.
For aged care teams, this is a disease that demands your attention; your residents are among those most vulnerable to its most severe complications.
diphtheria-outbreak-australia-aged-care-2026

What Is Diphtheria?

Diphtheria is a bacterial infection caused by Corynebacterium diphtheriae. Disease severity depends on whether the strain carries the tox gene – toxigenic strains produce the diphtheria toxin responsible for heart failure, paralysis, and death. Non-toxigenic strains can cause infection but rarely produce life-threatening illness. The current strain circulating in Australia is toxigenic. Diphtheria presents in two main forms:
  • Respiratory diphtheria - affects the throat and airways, producing a thick, greyish membrane causing a severe obstruction. This form is most likely to be life-threatening.
  • Cutaneous diphtheria - affects the skin, producing slow-healing sores or ulcers. In the current outbreak, this is the most common form. It still poses a risk, however, particularly through wound infection transmission.

The bacterial toxin is the real danger. Once it enters the bloodstream, it can cause heart failure and paralysis, even in those who appear to be recovering from the initial infection. Symptoms typically appear two to five days after exposure and can escalate rapidly. Diphtheria is transmitted by direct skin contact, the predominant route in the current Australian outbreak, respiratory droplets, cross-infection between the two forms of diphtheria and fomites (less common).

Why Older Residents Are at a Greater Risk

A resident who contracted diphtheria in their 70s or 80s is unlikely to experience the disease in the same way as a younger, healthier adult. The following explains why aged care residents are particularly vulnerable:
  • Waning immunity. Even people who were fully vaccinated in childhood show declining antibody levels by middle age. By the time a person reaches their 60s or 70s, protective immunity may be negligible, particularly if they haven't had a booster for decades.
  • Comorbidities. Heart disease, diabetes, respiratory conditions, and renal impairment all increase the risk of serious complications from the diphtheria toxin.
  • Immunosuppression. Residents receiving corticosteroids, chemotherapy, or other immunosuppressive therapies have a reduced capacity to fight the infection.
  • Delayed recognition. A sore throat and low-grade fever at the outset can look like any number of common conditions in an older person. The window for effective early treatment is narrow, and delays cost lives.
  • Higher fatality risk. Older people of both genders face a disproportionately higher risk of fatal complications from respiratory diphtheria. Pre-vaccine-era data showed that roughly one in ten people with respiratory diphtheria died, and that risk was highest in older (and younger) patients.
diphtheria-symptoms-aged-care-residents

What to Watch For

Your team should be alert to the following symptoms, particularly if a resident has had recent contact with someone from a higher-risk area or community:
Respiratory diphtheria:
  • Sore throat with or without a visible grey or white pseudomembrane on the tonsils or pharynx
  • Hoarseness or a barking cough
  • Stridor (a high-pitched breathing sound) is a red flag for airway obstruction
  • Low-grade fever
  • Swollen neck ("bull neck" appearance from swollen lymph nodes)
  • Nasal diphtheria, blood-stained or mucopurulent nasal discharge (rarer, more common in young children)

Cutaneous diphtheria:
  • Slow-healing skin ulcer-often with punched–out appearance with grey or dirty-yellow membrane base, typically on legs, arms, or feet.
  • Ulcers may be surrounded by redness and crusting.
  • Underlying skin conditions such as scabies, eczema, trauma is present- bacteria colonise on existing broken skin.
  • Systemic toxin effects are rare but possible; be alert for cardiac or neurological symptoms.

    If you suspect a case, isolate the resident and contact your local Public Health Unitimmediately. Do not wait for laboratory confirmation before acting. 

Treatment and Care

Diphtheria is a medical emergency. Treatment requires two components working together:
  • Diphtheria antitoxin (DAT) neutralises circulating toxin and is the mainstay of treatment for respiratory diphtheria. It must be administered as early as possible, as it cannot reverse damage already caused by the toxin. In Australia, DAT is not on the Australian Register of Therapeutic Goods and must be accessed via the Special Access Scheme. For guidance, contact your local Public Health Unit.
  • Antibiotics, typically erythromycin or penicillin, are used to eradicate the bacteria, halt toxin production, and prevent transmission. Parenteral (intravenous) antibiotic therapy is usually required initially.

Severe cases require hospitalisation, often in an intensive care setting. Your role as the facility team is to ensure early recognition, rapid escalation, and support for the resident's family through an extremely distressing situation. Close contacts of a confirmed case, including unvaccinated or under-vaccinated team members, may also require prophylactic antibiotics and review. Work with your Public Health Unit to manage this.

The Vaccination Problem — And Why It Matters More Than Ever

Here's the uncomfortable truth: in the current outbreak, an estimated 90% of cases have occurred in people who were previously vaccinated. This is evidence that immunity wanes and boosters matter.
Growing numbers of Australians are choosing not to vaccinate or to keep up with adult boosters, influenced by misinformation that has accelerated since the COVID-19 pandemic. At the same time, COVID-era disruptions suppressed the low-level community exposure that naturally helped top up immunity in vaccinated adults. The result is a population with weaker than-usual herd immunity and a disease that exploits every gap available.

The Australian Immunisation Handbook recommends:
  • A diphtheria-toxoid booster at age 50, and again at 65 if no booster has been given in the previous ten years
  • A dTpa booster (diphtheria, tetanus, and whooping cough) for adults every ten years from their early 20s onwards
  • Vaccination review for those working with or living in high-risk communities

For your team, this means two things:
  1. Encourage residents' families to check their vaccination status, as visitors can be a transmission risk.
  2. Review your own vaccination records. As a care worker or nurse, you are a potential vector. Many adult boosters are available for free through the National Immunisation Program; check your eligibility and keep your records up to date.

For residents who have never received a diphtheria booster in adulthood, discuss vaccination with their General Practitioner. It's never too late to reduce risk.

What Your Facility Should Do Now

This outbreak is an opportunity to move from reactive to proactive. Don't wait for a case to appear in your facility.
  • Audit your Standard Precautions training: is your team confident in respiratory hygiene, droplet and contact precautions, and the appropriate use of Personal Protective Equipment (PPE)?
  • Know your escalation pathway: does every team member know who to call if they suspect a notifiable disease? Diphtheria is a nationally notifiable condition in Australia.
  • Brief your team: a short huddle on diphtheria recognition and response is worthwhile now, while it's in the news and people are receptive.
  • Check your PPE stocks: isolating a suspected case will require surgical masks, gloves, and gowns at a minimum.
  • Engage families: consider a brief message to families reminding them to stay home if unwell and to check their vaccination status.
diphtheria-vaccination-older-adults

The Bottom Line

Diphtheria was supposed to be a disease of the past. The current outbreak, and the death it has now claimed, is a reminder that vaccine-preventable diseases don't disappear on their own. They disappear when communities stay vaccinated, vigilant, and proactive. Your residents are counting on your team to recognise the signs, act quickly, and protect your facility. That starts today.

Sources: Australian Centre for Disease Control (ACDC), 2026; Australian Immunisation Handbook (Department of Health and Aged Care, 2026); National Centre for Immunisation Research and Surveillance (NCIRS), 2026; The Conversation, May 2026; Healthdirect Australia, 20

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