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Page last updated on 17 February 2021

Diphtheria is a severe inflammation of nose, throat and windpipe caused by the bacterium Corynebacterium diphtheriae

The disease is rare in most developed countries including Australia due to routine vaccination. However, cases of diphtheria do still occur in Australia. In February 2018, in far North Queensland, a 20 year old man who was not vaccinated against the disease, died due to complications.

Australia generally has high levels of protection against the disease, especially due to the inclusion of the vaccine on the National Immunisation Program (NIP). However, past outbreaks in other countries have been concentrated in poorly immunised, disadvantaged groups living in crowded conditions and low levels of immunity to diphtheria have been found in Australian adults.

Diphtheria vaccines are part of the NIP and they are provided free to infants, children and adolescents. To find out more about diphtheria immunisation, speak with your healthcare professional.

Key disease information

What is diphtheria?

Diphtheria is a bacterial disease that causes severe inflammation of the nose, throat and windpipe. 

The bacteria produce a toxin (poison) that attacks the lining of the back of the throat. The throat becomes inflamed and rapidly forms an abnormal membrane (barrier) over the back of the throat, which can make swallowing and breathing difficult. This alone can lead to suffocation.

The toxin can also spread throughout the bloodstream and affect other organs, including the heart and kidneys, as well as the nervous system. These complications can be fatal.

Vaccination is an effective way to prevent diphtheria.The disease is extremely rare in Australia due to ongoing routine vaccination programs.

How is diphtheria spread?

Diphtheria is spread from person-to-person by coughing or sneezing.

In Australia, it is now more common in adults rather than children – as most children have high levels of immunity due to immunisation programs. To prevent the spread of diphtheria, high levels of immunity are required in all age groups – which is why both adults and children are advised to be vaccinated against diphtheria.

In rare cases, the bacteria that cause diphtheria can cause a skin infection (called cutaneous diphtheria), and in these cases, the disease may spread by having contact with pus from the wound.

How severe is diphtheria?

Diphtheria can be life threatening if left untreated.  

The disease can escalate from its initial phase (2-3 days) of sore throat, fever and loss of appetite to severe weakness and death (6-10 days).

Rapid and effective treatment is important, however even with treatment, about 1 out of 10 people who contract diphtheria will die.

How is diphtheria prevented?

The most effective way to prevent diphtheria is by vaccination. 

Vaccination against diphtheria is part of the National Immunisation Program (NIP). The diphtheria vaccine is given at 6-8 weeks, 4 and 6 months of age along with tetanus and whooping cough vaccines, with boosters at 18 months, 4 years and 10-15 years of age. In Australia, the vaccines used for immunisation against diphtheria in adults, also protects against tetanus or tetanus and whooping cough.



Because immunity acquired through vaccination against diphtheria wanes over time, older adults may no longer be immune. A diphtheria-containing vaccine booster is recommended for adults aged 50 years and over if their last dose was more than 10 years ago. Talk to your doctor about when a booster for diphtheria should be given.

Diphtheria can be a risk for travellers to some countries. Speak with your healthcare professional if you are planning to travel and they can advise whether you require a booster dose against diphtheria.

In addition to vaccination, the practice of good personal hygiene and isolation of patients will help decrease spread of the bacteria.

To find out more about diphtheria immunisation, speak with your healthcare professional.

To find out more about diphtheria immunisation, speak with your healthcare professional.

How common is diphtheria now?

Due to routine vaccination diphtheria is now rare in Australia and other developed countries. However, in the cases that are reported diphtheria is now more commonly seen in adults than in children.

Although rare in Australia, diphtheria still occurs in many developing countries. In particular, Asia, the South Pacific, the Middle East, and in Haiti and the Dominican Republic. Outbreaks have occurred in Indonesia, Bangladesh, Myanmar, Vietnam, Venezuela, Haiti, South Africa and Yemen, since 2016.

If you are planning an overseas trip, make sure you are up-to-date with your immunisations.


Can adults get diphtheria?

Yes, adults can contract diphtheria and in fact, in Australia it is now more commonly seen in adults than in children. 

Diphtheria can affect people of all ages. In countries where it is more common, it mostly affects young children. However, in Australia (where we have high vaccination rates due to childhood immunisation programs) approximately 80% of cases from 2018 to 2019 were in adults.

Your protection against or immunity to diphtheria decreases over time, leaving you unprotected against infection. To maintain protection it is recommended that you speak with your healthcare professional about keeping your vaccinations up-to-date.


Is diphtheria contagious?

Yes, diphtheria is highly contagious and is easily spread by coughing or sneezing. 

Without treatment, people with diphtheria are infectious for up to 4 weeks from the beginning of their symptoms. Some people can also become carriers and are infectious for longer.

Completing the immunisation schedule is important, as those who have not been fully immunised are at risk of developing the disease if they are exposed to the bacteria.


VaccineHub offers general information only. Please see a healthcare professional for medical advice

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Sources & Citations

  1. Australian Government. Department of Health. Australia’s notifiable disease status, 2014: Annual report of the National Notifiable Diseases Surveillance System (main page). Available at: (accessed 27 February 2020).
  2. Victorian Government. Better Health Channel. Diphtheria. Available at: (accessed 27 February 2020).
  3. Australian Government. Department of Health. National Notifiable Diseases Surveillance System. Number of notifications for diphtheria, Australia, 1991 to 2019 and year-to-date notifications for 2020. Available at: (accessed 27 February 2020).
  4. ABC News. Diphtheria death shows Queensland is failing to properly vaccinate, AMA warns. 8 February 2018. Available at: (accessed 27 February 2020).
  5. Australian Government. Department of Health. Diphtheria in Australia, recent trends and future prevention strategies. Available at: (accessed 27 February 2020).
  6. Lu X, et al. Infect Disord Drug Targets 2018; doi: 10.2174/1871526518666181011114834 [Epub ahead of print].
  7. Centers for Disease Control. Diphtheria. Symptoms. Available at: (accessed 27 February 2020).
  8. Centers for Disease Control. Chapter 3, infectious diseases related to travel. Diphtheria. Available at: (accessed 27 February 2020).
  9. Centers for Disease Control. Diphtheria. Diagnosis and Treatment. Available at: (accessed 27 February 2020).
  10. The Australian Immunisation Handbook. Diphtheria. Available at: (accessed 27 February 2020).
  11. National Immunisation Program Schedule. Australian Government, Department of Health. Available at: (accessed 27 February 2020).

SPANZ.SAPAS.18.04.0134(1) - Date of preparation March 2020