The Diphtheria Outbreak - What You Should Know
- Tara Ly
- May 25
- 3 min read
Updated: May 28
Highly contagious and potentially fatal, Diphtheria was a common cause of death for Australian children until the 1940s. It was added to the list of nationally notifiable diseases in 1991, and case numbers have typically been between zero and 12 per year.
However, in the first 4 months of 2026 there were already 230 reported cases - this represents a 30‑fold increase. The majority have been Aboriginal and Torres Strait Islander people. It has been particularly bad in the Northern Territory and Western Australia with a growing number in Queensland and South Australia.
Fortunately, most have been relatively mild cases which has been attributed to Australia’s high level of vaccination.
WHAT IS DIPHTHERIA?
Diphtheria is a contagious infection caused by toxic strains of the bacteria Corynebacterium diphtheriae and Corynebacterium ulcerans. It usually affects the nose, throat and tonsils (respiratory diphtheria) but can also affect the skin (cutaneous diphtheria). With the current outbreak approx. 70% have been cutaneous diphtheria (skin) and 30% respiratory diphtheria.
It's the toxin produced by the bacteria that makes it so dangerous. Within just 2–3 days, this can cause a greyish-white film to form over the throat and tonsils, making it difficult to swallow or breathe. It can also harm your heart, kidneys and nerves.
Cutaneous diphtheria is more common in tropical climates and causes sores on the skin, often on the legs. These can turn into larger ulcers and are typically slow to heal.
WHAT ARE THE SYMPTOMS OF DIPHTHERIA?
Symptoms typically develop 2–5 days after exposure, though in some cases they may take up to 10 days. The symptoms depend on where the infection occurs in your body.
People with diphtheria can be infectious for up to 4 weeks after symptoms start. Antibiotic treatment can shorten this period.
In respiratory diphtheria, the symptoms usually include:
Sore throat
Loss of appetite
Mild fever
HOW IS DIPHTHERIA SPREAD?
Diphtheria usually spreads in the air when an infected person coughs or sneezes.
It can also spread by touching saliva, mucus, or skin sores from an infected person, including contaminated objects. It has been known to spread from animals to humans through contact with or consuming raw milk.
WHO IS AT RISK OF DIPHTHERIA?
Anyone who is not fully vaccinated is at risk.
People travelling to countries with low vaccination rates, such as parts of the South Pacific, South and South-East Asia, the Middle East, Eastern Europe, South and Central America, may be at higher risk.
HOW CAN DIPHTHERIA BE PREVENTED?
Vaccination is the best protection against diphtheria.
Commonly called the Whooping Cough Vaccine, the injection delivers 3 vaccines in one:
Diphtheria
Tetanus, and
Pertussis (dTpa)
Under the Australian Government’s National Immunisation Program (NIP), the vaccine free for the following groups:
Young children aged 2 months to 4 years
Adolescents aged 12-13 years
Pregnant women (between 20-32 weeks of pregnancy)
People under 20 years old, refugees and other humanitarian entrants of any age
Vaccination For Children
Children should be vaccinated at:
6 weeks
4 months
6 months
18 months
4 years
Children receive a booster at 11-13 years through the NSW School Vaccination Program.
Vaccination for adults
Diphtheria boosters are recommended:
At least 2 weeks before travel for people travelling to high-risk areas if their last dose was more than 5 years ago.
Adults aged 50 years and older if their last dose was more than 10 years ago.
Adults aged 65 years and older if their last dose was more than 10 years ago.
Every 10 years for laboratory workers exposed as part of their job.
HOW IS DIPHTHERIA DIAGNOSED?
Diphtheria is diagnosed through a swab test, usually from the throat. Skin swabs may be taken if sores are present, and samples are sent to a laboratory.
HOW IS DIPHTHERIA TREATED?
Treatment includes antibiotics. Serious cases may require hospitalisation and antitoxin medication.
High community vaccination rates are essential to protect against this disease. But it is important to understand that vaccination does not guarantee immunity, but if you do contract it then it is usually less severe.
