Diphtheria

Key points

1. Diphtheria is highly contagious. It is usually spread from person to person by breathing in droplets after an infected person coughs, sneezes or laughs, or from coming into contact with contaminated items.
2. Some people carry the diphtheria bacteria and spread the infection, even though they don't develop symptoms.
3. Diphtheria must be treated quickly to prevent serious complications developing, such as breathing problems, heart problems, kidney failure, paralysis. It can even be life threatening. 
4. Vaccination is the best way to protect against diphtheria. People who have not been vaccinated against diphtheria are most at risk of getting it. 
5. Travellers visiting countries where diphtheria is still common should make sure they have received a diphtheria booster in the last 10 years.

Diphtheria

"Diphtheria is a rare but serious infectious disease. The bacteria usually causes infection of the throat and nose but can also cause skin infections. Cases of diphtheria in New Zealand have declined significantly over the last century with very few cases reported in the last 50 years."

 (The Immunisation Advisory Centre, NZ)

What is diphtheria?

Diphtheria is caused by a bacteria that is easily spread from person to person. The infection affects your airways, tonsils, throat, nose and sometimes your skin. The bacteria can produce dangerous toxins which, if left untreated, can lead to breathing problems, heart problems, kidney failure, paralysis or may even be life threatening.

How is diphtheria spread?

Diphtheria is very contagious. It is usually spread from person to person by breathing in droplets produced after an infected person coughs, sneezes or laughs. It can also be spread by contact with items contaminated by a person with diphtheria, such as used drinking glasses, tissues, bedding or clothing. In rare cases, it can also be spread by contact with infected skin sores. 

Some people may carry the diphtheria bacteria and spread the infection, even though they do not develop symptoms.

What are the symptoms of diphtheria?

The common symptoms of diphtheria include:

• a sore throat and difficulty swallowing
• a thick grey-white coating at the back of your throat
• a high temperature (fever) of 38°C or above
• breathing difficulties.

Other symptoms may include chills, tiredness, hoarse voice, cough and headache. At first, diphtheria may be often mistaken for a simple sore throat or throat infection, but the symptoms quickly get worse.   

Diphtheria can sometimes affect your skin rather than your throat. This is known as cutaneous diphtheria. The symptoms of cutaneous diphtheria can range from ulcers to pus-filled blisters to a scaly rash.

Complications from diphtheria may include:

• blocking of your airway
• damage to your heart muscle (myocarditis)
• nerve damage (polyneuropathy)
• loss of your ability to move (paralysis)
• lung infection (respiratory failure or pneumonia).

For some people, diphtheria can lead to death. 

How is diphtheria diagnosed?

Doctors can usually diagnose diphtheria based on symptoms and signs they find when they examine you. If they suspect you have diphtheria, they may take a sample of cells (swab) from your throat, nose or wound on your skin to send to the laboratory. This can be examined to see whether the bacteria that cause diphtheria are present.

How is diphtheria treated?

People suspected of having diphtheria will be given an antitoxin injection into a muscle or vein. The antitoxin works by counteracting the diphtheria toxin present in your bloodstream. Since diphtheria is caused by a bacteria, antibiotics are also needed to kill the bacteria directly.

Diphtheria must be treated quickly to prevent serious complications developing. Diphtheria can be fatal – even with treatment, about 1 in 10 diphtheria patients die. Without treatment, up to half of patients can die from the disease.

Reducing the spread

Local health officials must be notified when cases of diphtheria occur. To prevent the spread, the infected person will be advised to have minimal contact with others until they are recovered. Also, health authorities may undertake contact tracing to identify people who may have come in contact with an infected person. They are likely to be at risk of infection.

People with diphtheria can reduce passing it to others by not going to school or work and avoiding large gatherings until you are completely recovered and have had 2 throat swabs that are clear of the bacteria. 

People who have been in close contact with an infected person may be offered a diphtheria booster vaccination and preventive doses of antibiotics.

How can I prevent diphtheria?

The best protection against diphtheria is having a complete course of 3 doses of diphtheria-containing vaccine, plus booster doses. You cannot get diphtheria from the vaccine.

• In New Zealand, the diphtheria vaccine is combined with other vaccines and is part of the National Immunisation Programme.
• Babies receive their diphtheria vaccinations at the age of 6 weeks, 3 months and 5 months. 
• Booster doses are given to children when they are aged 4 and 11 years old.
• To ensure protection continues, a diphtheria booster vaccination is offered at 45 and 65 years of age. 
• Travellers visiting countries where diphtheria is still common should make sure they have received a diphtheria booster in the last 10 years.
• Even if you've had diphtheria, you will still need to get vaccinated. Contracting diphtheria does not provide lasting immunity.

Read more about diphtheria vaccines.

Learn more

Diphtheria Ministry of Health, NZ, 2017

References

1. Diphtheria Immunisation Handbook, NZ, 2017

Reviewed by

	Dr Li-Wern Yim is a travel doctor with a background in general practice. She studied medicine at the University of Otago, and has a postgraduate diploma in travel medicine (Otago). She also studied tropical medicine in Uganda and Tanzania, and holds a diploma from the London School of Hygiene & Tropical Medicine. She currently works in clinical travel medicine in Auckland.