Diphtheria is an infectious disease caused by toxigenic strains of the bacterium Corynebacterium diphtheria. Vaccination has eradicated it from Australia, apart from the occasional imported case brought in by an unvaccinated person.
Travellers to Southeast Asia, India, Nepal, Bangladesh, Eastern Europe, New Guinea, the Baltic and the former Soviet Union are particularly at risk and should be up to date with their booster vaccinations.
Diphtheria is transmitted from person to person by breathing in respiratory droplets when an infected person coughs or sneezes, by oral contact, close physical contact, by contaminated personal objects such as blankets, or in the case of cutaneous diphtheria, contact with infected skin lesions.
The incubation period is 2-5 days. The disease can affect any of the mucous membranes, but usually causes infection in the upper respiratory tract, where it affects the mucous membrane of the pharynx (the back of the throat), and can produce a grey or green membrane which covers the back of the throat and the tonsils and obstructs breathing.
Respiratory diphtheria has a gradual onset, with symptoms such as mild fever, sore throat, difficulty swallowing, fatigue, hoarse voice, cough, swollen neck glands, smelly discharge from nose and difficulty breathing.
In addition, toxins produced by the bacteria can affect the nerves and the heart, with life-threatening complications.
Diphtheria affecting the skin (cutaneous diphtheria) can cause pus-filled spots, which form into larger slow-healing skin ulcers. These usually occur on the legs, feet and hands.
Diphtheria is diagnosed by taking a throat or nose swab and looking at it under the microscope to see if the bacteria that cause diphtheria are present. In the case of cutaneous diphtheria (diphtheria of the skin), a skin swab is taken. Testing for the presence of diphtheria toxin is also usually undertaken.
A person with suspected diphtheria will be isolated to stop the spread of the infection. Treatment of diphtheria is three-fold:
- Antibiotics to kill the diphtheria bacteria.
- Antitoxins to neutralise the bacterial toxins.
- Membrane removal: if a grey-green membrane has formed at the back of the throat, this will be removed.
Close contacts and family will need to be tested to make sure they have not caught diphtheria.
Diphtheria vaccination is part of the Australian Standard Vaccination Schedule for Australian children. Boosters are recommended at 15-17 years and also at 50 years (unless a booster was given in the previous 10 years). Diphtheria vaccination is given in combination with tetanus and pertussis (whooping cough).
People travelling to countries where vaccination is not widespread, such as those mentioned above should check whether they are up to date with their diphtheria vaccination.