Diphtheria is a potentially fatal contagious bacterial infection that mainly affects the nose and throat, and sometimes the skin.
Diphtheria is highly contagious. It’s spread by coughs and sneezes, or by contact with someone with diphtheria or items belonging to them, such as bedding or clothing.
Diphtheria is very rare in England because most people have been vaccinated against it.
The symptoms of diphtheria include:
- a thick grey-white coating at the back of the throat
- a high temperature (fever) of 38C (100.4F) or above
- sore throat
- breathing difficulties
Older people and people with a weakened immune system are more at risk of the effects of diphtheria. The most serious cases can be fatal.
An estimated 5-10% of people who get the infection will die from complications of diphtheria, such as breathing difficulties, inflammation of the heart (myocarditis) or problems with the nervous system.
A diagnosis of diphtheria can be confirmed by taking a sample of cells from the throat, nose or wound on the skin.
This will be examined to see whether the bacteria that cause diphtheria are present.
Diphtheria must be treated quickly to prevent serious complications developing. If diphtheria is suspected, treatment will begin before any test results are confirmed.
Treatment for diphtheria comprises antibiotics and antitoxin medicine. Anyone suspected of having the condition will be put in isolation when they’re admitted to hospital. Those who develop heart and nervous system complications will need specialist treatment, and may need to be admitted to the intensive care ward.
All children should be vaccinated against diphtheria as part of the routine childhood vaccination schedule.
Adults should consider having a booster vaccine when travelling to parts of the world where diphtheria is widespread.
How common is diphtheria?
Before a vaccination programme was introduced in 1940, diphtheria was a very common condition and one of the leading causes of death in children.
The vaccination programme has been very successful. Since 2010, there have been only 20 recorded cases of diphtheria in England and Wales, and one death. Diphtheria is a notifiable disease, which means that if a doctor diagnoses the condition, they must tell the local authority.
Even though the numbers of diphtheria cases in England is low, there’s a risk that an outbreak could occur if the number of people who are vaccinated falls below a certain level.
This risk was demonstrated by the diphtheria epidemic that struck the countries of the former Soviet Union between 1990 and 1998. It resulted in 157,000 cases and 5,000 deaths. The epidemic was caused by an increase in the number of children who were not vaccinated against the disease.
All children should be vaccinated against diphtheria at two months of age as part of the routine childhood vaccination schedule.
Symptoms of diphtheria
The symptoms of diphtheria usually begin two to seven days after you become infected.
The time it takes for symptoms to develop is called the incubation period.
If you have diphtheria, a grey-white coating (membrane) can develop inside your throat. It covers the back of your throat and tonsils, and can obstruct your breathing.
Symptoms of diphtheria also include:
- a high temperature (fever) of 38C (100.4F) or above
- fatigue (extreme tiredness)
- sore throat
- hoarse voice
- difficulty swallowing or pain when swallowing
- difficulty breathing
- foul-smelling, bloodstained nasal discharge
- swollen glands (nodes) in the neck
- pale, blue skin
Diphtheria that affects the skin
Diphtheria can occasionally affect the skin rather than the throat. This is known as cutaneous diphtheria.
If you have cutaneous diphtheria, you will develop pus-filled spots on your skin, usually on your legs, feet and hands. These blisters and spots will form into a large ulcer surrounded by a red patch of discoloured, sore-looking skin. The ulcer usually heals within two to three months, but it’s likely to leave a scar.
Causes of diphtheria
Two types of bacteria can cause diphtheria.
- Corynebacterium diphtheriae
- Corynebacterium ulcerans
The bacteria spread when an infected person coughs or sneezes and droplets of their saliva enter another person’s mouth or nose. The bacteria can be transferred by an infected person onto household items, such as cups, towels or cutlery.
Diphtheria is usually caught after being in close or prolonged contact with someone who has the condition or is carrying the infection. For example, you may catch diphtheria from someone you live with.
In countries where standards of hygiene are poor, diphtheria can often affect the skin (cutaneous diphtheria). In these cases, the bacterial infection is spread through contact with the infected wound rather than by breathing in infected droplets.
Infection from animals
You can become infected with Corynebacterium ulcerans after coming into close contact with cattle, because they carry the bacteria in their nose and throat.
You can also become infected with the bacteria after drinking unpasteurised milk or eating food made with unpasteurised milk.
Where diphtheria occurs
Diphtheria is rare in the UK, because the diphtheria vaccination is part of the routine childhood vaccination schedule.
However, diphtheria can be more common in parts of the world where fewer people are vaccinated, such as:
- South Asia
- the former Soviet Union
If diphtheria is suspected, you will be immediately admitted to an isolation ward in hospital to stop the infection spreading to other people.
If the grey-white membrane is making it difficult for you to breathe, some or all of it will be removed.
A diphtheria infection is treated using two types of medication:
- antibiotics to kill the diphtheria bacteria
- antitoxins to neutralise the effects of the toxin produced by the bacteria
Most people who have diphtheria require a 14-day course of antibiotics. After this time, you’ll have tests to find out if all the bacteria have gone. If diphtheria bacteria are still present, you may need to continue taking antibiotics for another 10 days.
Once you have completed the treatment, you won’t be infectious to other people. However, you won’t be able to leave the isolation ward until tests show that you’re completely free of infection.
You should have the diphtheria vaccination after you’ve been treated, because having diphtheria doesn’t always stop you getting the infection again.
Testing and treating close contacts
Anyone who has had close contact with you, such as family or household members, visitors and anyone you have kissed or had sex with, should visit their GP immediately to be checked for signs of diphtheria.
Testing for diphtheria involves taking a sample of cells from the nose to test for the diphtheria bacteria. Your close contacts will be prescribed antibiotics. It’s very important that they finish the course. If necessary, they will also be given a booster dose of the diphtheria vaccination.
Any healthcare workers who have cared for someone with diphtheria may also need to be tested and treated.
The risk of catching diphtheria from work colleagues or school friends is very low.
Cutaneous diphtheria is diphtheria that affects the skin rather than the throat. It’s treated by thoroughly washing any wounds infected with soap and water. You’ll be tested two weeks later to make sure that all of the bacteria have gone.
Complications of diphtheria
Diphtheria can lead to potentially life-threatening complications, such as breathing difficulties and problems with the heart and nervous system.
Diphtheria can cause serious breathing difficulties because:
- the membrane that covers your throat can make breathing difficult
- small particles of the membrane can fall down into your lungs, leading to widespread inflammation of the lungs
There’s a risk that someone with diphtheria will lose their normal lung function. This is called respiratory failure.
If you’re considered at risk of respiratory failure, a ventilator will be used to help with your breathing. The ventilator will move oxygen-enriched air in and out of your lungs while the underlying infection is treated.
The toxin that’s produced by diphtheria bacteria can inflame the muscles of your heart. Inflammation of the heart muscles is known as myocarditis.
Myocarditis can cause your heart to beat irregularly, causing heart block. This is when the electrical pulses that control the beating of your heart are disrupted, causing your heart to beat very slowly (bradycardia).
The heart block can be treated with a temporary pacemaker. It can be inserted into your chest to help your heart beat regularly.
In the most serious cases of myocarditis, the heart can become so weak that it can’t pump blood around your body and you will have heart failure.
Nervous system complications
Diphtheria can cause complications that affect the nervous system (neurological complications). These can occur weeks after you first experience diphtheria symptoms.
Paralysis of the diaphragm
One possible complication is your diaphragm being paralysed. The diaphragm is a thick dome-shaped muscle that separates your chest from your abdomen. It helps you breathe in and out.
If the diaphragm is not working properly, you will need a ventilator to help you breathe. This can mimic the function of your diaphragm by regulating the pressure of your lungs. Unless you are put on a ventilator immediately, paralysis of the diaphragm can be fatal.
The diaphragm can become paralysed very suddenly, over a period of around 30 minutes. It can become paralysed weeks after you first develop diphtheria, even after you have recovered from the initial infection and any other complications.
For this reason, children with diphtheria and other complications, such as those affecting the heart, may be kept in hospital for up to six weeks, even if they appear to be better.
Another possible complication is problems with the nerves controlling your bladder (neurogenic bladder dysfunction). If these nerves are damaged, you won’t be able to fully empty your bladder.
This can cause symptoms such as:
- needing to urinate often
- only passing a small amount of urine
- losing control of your bladder
Bladder problems often develop before paralysis of the diaphragm, so this can be an early warning sign that you’ll develop more serious breathing problems.
Malignant diphtheria, also known as hypertoxic diphtheria or diphtheria gravis, is a very severe form of diphtheria. As well as the other symptoms of diphtheria, people with malignant diphtheria develop:
- severe bleeding problems
- kidney failure
Malignant diphtheria is often fatal. It’s likely to be caused by a particular type of Corynebacterium diphtheriae bacteria.
The most effective way of preventing diphtheria is to ensure all of your vaccinations are up-to-date.
Vaccinations for diphtheria are part of the routine NHS childhood vaccination schedule.
In total, children should receive five doses of the diphtheria vaccination. It’s usually combined with other vaccines. For most people, five doses provide a good level of protection against diphtheria for the rest of their life.
All babies are offered vaccination against diphtheria as part of the 5-in-1 vaccine that is given when they’re two, three and four months old. The 5-in-1 vaccine, also known as the DTaP/IPV/Hib vaccine, also protects against:
A booster vaccine against diphtheria is given as part of the 4-in-1pre-school booster (also called the DTaP/IPV vaccine) to children who are about three years and four months old. The 4-in-1 vaccine protects against diphtheria, tetanus, whooping cough and polio.
A final booster dose of diphtheria vaccine is given as part of the 3-in-1 teenage booster (also called the Td/IPV vaccine) to children when they’re 13 to 18 years old. The 3-in-1 vaccine protects against diphtheria, tetanus and polio.
If you’re not sure whether your family’s vaccinations are up-to-date, ask at your GP surgery.
Travel vaccination against diphtheria
Further booster diphtheria vaccinations may be required if you’re going to live or work in parts of the world where diphtheria is widespread. You should have a booster dose if your last dose was more than 10 years ago.
Regions known to have high rates of diphtheria include:
- Papua New Guinea
- sub-Saharan Africa (particularly Nigeria)
However, the areas that are considered to be high-risk for any disease can change. For up-to-date travel information, you can check: