Diphtheria is caused by the bacteria Corynebacterium diphtheriae. 

Diphtheria can cause throat and skin infections and was the most common fatal infectious disease 100 years ago. The most serious infections are linked to a toxin that some types of the bacteria produce.

This toxin can spread throughout the body from the throat or skin to cause inflammation of nerves, kidneys and heart muscle and can be fatal.

Since the introduction of a vaccine in the 1940s the disease is now very rare in countries with high vaccination rates. However cases still do occur as 2 people in Australia contracted toxinproducing diphtheria in 2011 from a contact who had recently travelled to a neighbouring country.

One of the cases, a young, unvaccinated woman died. It is important that people are fully immunised from childhood onward and check their vaccination status before travelling overseas.

How it's spread 

Diphtheria is spread from person to person by inhaling respiratory secretions from infected people and sometimes by direct contact with discharges from lesions of infected people.

Infectious period

A person with diphtheria is usually infectious for about 2 to 4 weeks. A person becomes non-infectious after receiving appropriate antibiotic therapy.

Signs and symptoms

Throat infections usually start gradually with fever and a sore throat. Toxin production by the bacteria causes a membrane to form over the back of the throat and tonsils. This membrane has a characteristic grey appearance and it can cause severe swelling of the throat making it difficult to breathe. There is often associated swelling of the lymph nodes in the neck. 

Diphtheria skin infections are non-distinctive shallow ulcers and only rarely involve toxin- producing strains. It is very rare for diphtheria skin infections to spread to involve other parts of the body.


Throat infections are diagnosed based on the signs and symptoms of the patient. The diagnosis is confirmed by culture of Corynebacterium diphtheriae from nose, throat or skin swabs. A test is then performed to determine if it is a toxin-producing strain of diphtheria.


People suspected of having throat infection caused by diphtheria are usually admitted to hospital for antibiotics and diphtheria anti-toxin. 

Uncomplicated skin infections caused by non toxin-producing diphtheria can be treated with antibiotics alone.


A diphtheria-containing vaccine is given routinely: 

  • at 2, 4 and 6 months of age
  • as a booster at 18 months, 4 years and 15 years
  • to adults under 50 years of age who are planning on travelling overseas if a booster has not been given in the last 10 years
  • at age 50 if a booster has not been given in the last 10 years. 

Diphtheria vaccination is always given as a diphtheria-tetanus or diphtheria-tetanus-pertussis (whooping cough) combination vaccine. Vaccination is highly effective at preventing diphtheria infection.

Close contacts of patients with toxin-producing diphtheria should be monitored, given advice and provided with preventive antibiotics to minimise the chance of becoming unwell with diphtheria.

A booster vaccine should be offered if indicated.


For more information contact the Centre for Disease Control.

Last updated: 12 May 2016

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