Diphtheria
Introduction
Diphtheria is a contagious bacterial infection that mainly affects the nose and throat. Less commonly, it can also affect the skin.
Diptheria is highly contagious. The bacteria spread when an infected person coughs or sneezes, and droplets of their saliva enter another person’s mouth or nose.
Diphtheria is very rare in Wales because most people have been vaccinated against it.
The symptoms of diphtheria include:
- high temperature (fever) of 38ºC (100.4ºF) or above
- sore throat
- breathing difficulties
Treating diphtheria
Diphtheria is treated with antibiotic and antitoxin medicine. Anyone suspected of having the condition will be isolated in hospital.
Children are particularly vulnerable to the effects of diphtheria. The most serious cases can be fatal.
An estimated 5-10% of people who get diphtheria will die from complications that arise from the condition, such as breathing difficulties, inflammation of the heart (myocarditis) or problems with the nervous system.
Vaccination
All children should be vaccinated against diphtheria as part of their routine childhood vaccination schedule. Adults should consider receiving a booster vaccine when travelling to parts of the world where diphtheria is widespread. See Diphtheria - prevention for more information and advice about the diphtheria vaccination.
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. In 2010, there were just eight recorded cases of diphtheria in England and Wales, and no deaths. Diphtheria is a notifiable disease, which means that if a doctor diagnoses the condition, they must tell the local authority.
Even though the incidence of diphtheria in Wales 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 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 diphtheria.
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Symptoms
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.
Symptoms of diphtheria can include:
- high temperature (fever) of 38ºC (100.4ºF) or above
- chills
- fatigue (extreme tiredness)
- sore throat
- hoarse voice
- cough
- headache
- difficulty swallowing or pain when swallowing
- difficulty breathing
- foul-smelling, bloodstained nasal discharge
- swollen glands (nodes) in the neck
If you have diphtheria, a grey-white membrane can develop inside your throat. It covers the back of your throat and tonsils and can obstruct your breathing. The membrane will bleed if you try to remove it.
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.
Asymptomatic diphtheria
People who have been vaccinated against diphtheria won't develop any symptoms if they become infected (asymptomatic diphtheria). However, it's still possible for these people to spread the infection to others.
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Causes
Two types of bacteria can cause diphtheria.
They are:
- 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. Less commonly, the bacteria that cause diphtheria can be transferred by an infected person onto household items, such as glasses, towels or eating utensils.
Therefore, diphtheria is usually caught after being in close, 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 such 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 being in close contact with cattle because these animals carry the bacteria in their nose and throat. You can also become infected with the bacteria after drinking unpasteurised milk or eating food that's made with unpasteurised milk.
How the condition develops
Once a person is infected, the bacteria quickly multiply and spread through the inside surface of the mouth, throat and nose. The bacteria produce a toxin (poison), which begins to kill the cells in the throat. The dead cells rapidly build up and form the grey-white membrane in the throat (see Diphtheria - symptoms).
The toxin can also spread through the blood and damage the heart and nervous system.
Where diphtheria occurs
Diphtheria is rare in the UK because diphtheria vaccination is part of the routine childhood vaccination schedule. However, diphtheria may be more common in countries where less people are vaccinated, such as:
- Africa
- South Asia
- the former Soviet Union
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Diagnosis
Diphtheria can usually be diagnosed by checking for its distinctive symptoms (see Diphtheria - symptoms).
In particular, a grey-white membrane in the throat would strongly suggest the presence of diphtheria.
Swabs
A suspected diagnosis of diphtheria can be confirmed by taking a small sample of cells from the:
- throat
- nose
- wound on the skin
The sample is collected with a swab, which is similar to a cotton bud. The sample will be examined under a microscope to see whether the bacteria that cause diphtheria are present.
Diphtheria must be treated quickly to prevent serious complications developing. Therefore, if diphtheria is suspected, treatment is likely to begin before any test results are confirmed.
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Treatment
If diphtheria is suspected, you will be immediately referred to hospital and admitted to an isolation ward to prevent the infection spreading.
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. Your recommended dose will vary depending on how severe your condition is and how long you've had diphtheria.
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 prevent diphtheria from infecting you 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
Cutaneous diphtheria is diphtheria that affects the skin rather than the throat. It's treated by thoroughly washing any wounds that are infected with the diphtheria bacteria with soap and water. You'll be tested two weeks later to ensure that all of the bacteria have gone.
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Complications
Diphtheria can lead to potentially life-threatening complications.
Respiratory failure
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 much or all of their normal lung function. This is called respiratory failure.
If you're considered at risk of respiratory failure, an artificial breathing machine called 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.
Myocarditis
The toxin that's produced by the 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, most often 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. This is a small electrical device that's similar to a battery. 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 your first experience diphtheria symptoms.
Paralysis of the diaphragm
One possible complication is your diaphragm being paralysed. Your diaphragm is a thick dome-shaped muscle that separates your chest from your abdomen. It helps you breathe in and out.
Without a functioning diaphragm, you need a ventilator to help you breathe. This can replicate the function of your diaphragm by regulating the pressure of your lungs. Unless you're put on a ventilator immediately, paralysis of the diaphragm can be fatal.
The diaphragm can become paralysed very suddenly, over half an hour or so. It can become paralysed weeks after you first develop diphtheria. You may have recovered from the initial infection and any other complications, but paralysis of the diaphragm can still occur. 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.
Bladder problems
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
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 the Corynebacterium diphtheriae bacteria that cause diphtheria.
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Prevention
The most effective way of preventing diphtheria is to ensure that all of your and your family’s vaccinations are up to date.
Vaccination
Vaccinations for diphtheria are part of the routine 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.
All babies should be given the combined DTaP/IPV/Hib vaccine when they're two months old. This also vaccinates against:
This vaccination is followed by two more booster vaccinations, which are given at three months and four months of age.
Another booster dose of DTaP/IPV is also recommended for children who are about three years and four months old (the ‘pre-school’ booster). This protects against diphtheria, tetanus, whooping cough and polio.
A final booster dose of Td/IPV should be given to children when they're 13 to 18 years old. This protects against diphtheria, tetanus and polio.
If you're not sure whether your family’s vaccinations are up to date, you should ask at your GP surgery.
Travel vaccinations
Further booster 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 that are known to have high rates of diphtheria include:
- sub-Saharan Africa (all the countries to the south of the Sahara Desert, particularly Nigeria)
- India
- Nepal
- Bangladesh
- Indonesia
- Philippines
- Vietnam
- Laos
- Papa New Guinea
- Brazil
- Iraq
- Afghanistan
However, the areas that are considered to be high risk for any disease can change. For up-to-date travel information, you can check:
In the countries that had a diphtheria epidemic in the 1990s, diphtheria rates have now fallen. The countries affected were those that made up the former Soviet Union.
However, you may wish to have a booster vaccination as a precaution if you're visiting any of the countries of the former Soviet Union, such as:
- Russia
- Ukraine
- Latvia
- Belarus
- Estonia
Booster doses
Your risk of developing a diphtheria infection in the UK is very small. Additional booster doses of the diphtheria vaccine aren't usually required. However, if you have a job that puts you at increased risk of infection, such as a healthcare worker at an infectious disease unit or a laboratory worker at a microbiology laboratory, you may need to have additional vaccinations.
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