Whooping cough, sometimes referred to as pertussis, is an infection of the lining of the airways. It mainly affects the windpipe (trachea) and the two airways that branch off from it to the lungs (the bronchi).
Whooping cough is highly infectious. The condition is caused by a bacterium called Bordetella pertussis, which can be passed from person to person through droplets in the air from coughing and sneezing.
The condition is known as whooping cough because the main symptom is a hacking cough, which is often followed by a sharp intake of breath that sounds like a 'whoop'. The cough typically lasts for many weeks.
Who is at risk?
Whooping cough usually affects unvaccinated infants and young children. Older children, teenagers and adults also develop the condition. Whooping cough tends to be most severe in young infants. In rare cases, it can be fatal.
How common is it?
The introduction of a vaccination programme during the 1950s and the introduction of 4 in 1 booster jab and a further booster at 11-14 years means the annual number of cases of whooping cough is now very low. However, there has been an increase in the number of cases in recent years.
Over 200 cases of whooping cough were recorded in Ireland in 2011. Two children have died from whooping cough in the past ten years. Before the introduction of the whooping cough vaccine there would be thousands of new cases each year and many deaths.
Despite the number of cases falling, it is still important that all babies have the whooping cough vaccine so that they are protected against severe disease
The symptoms of whooping cough usually take 6-20 days to appear after infection with the Bordetella pertussis bacterium. This delay is known as the incubation period.
Whooping cough tends to develop in stages, with mild symptoms occurring first, followed by a period of more severe symptoms, before improvement begins.
The early symptoms of whooping cough are often similar to those of a common cold and may include:
- runny or blocked nose
- watering eyes
- dry, irritating cough
- sore throat
- slightly raised temperature
- feeling generally unwell
These early symptoms of whooping cough can last for one to two weeks, before becoming more severe.
The second stage of whooping cough is often called the paroxysmal stage and is characterised by intense bouts of coughing. The bouts are sometimes referred to as 'paroxysms' of coughing.
The paroxysmal symptoms of whooping cough may include:
- intense bouts of coughing, which bring up thick phlegm
- a 'whoop' sound with each sharp intake of breath after coughing (although this may not occur in infants and young children, see below)
- vomiting after coughing, especially in infants and young children
- fatigue (tiredness) and redness in the face from the effort of coughing
Each bout of coughing usually lasts between one and two minutes, but several bouts may occur in quick succession and last several minutes. The number of coughing bouts experienced each day varies, but is usually between 12 and 15.
The paroxysmal symptoms of whooping cough usually last at least two weeks, but can last longer, even after treatment. This is because the cough continues even after the Bordetella pertussis bacterium has been cleared from your body.
Infants and young children
Infants younger than three months may not make the 'whoop' sound after coughing, but they may start gagging or gasping, and may temporarily stop breathing. It is possible for whooping cough to cause sudden unexpected death in infants (see Whooping cough - complications for more information).
Young children may also seem to choke or become blue in the face (cyanosis) when they have a bout of coughing. This looks worse than it is, and breathing will quickly start again.
Adults and older children
In adults and older children, the paroxysmal symptoms of whooping cough are far less severe than they are in young children, and may appear more like the symptoms of a milder respiratory infection, such as bronchitis.
Eventually, the symptoms of whooping cough gradually start to improve, with fewer and less extreme bouts of coughing occurring. This period of recovery can last up to three months or more.
However, intense bouts of coughing may still occur during this period.
Whooping cough is caused by a bacterium called Bordetella pertussis. The bacterium infects the lining of the airways, mainly the windpipe (trachea) and the two airways that branch off from it to the lungs (the bronchi).
When the Bordetella pertussis bacterium comes into contact with the lining of these airways, it multiplies and causes a build-up of thick mucus. It is the mucus that causes the intense bouts of coughing as your body tries to expel it.
The bacterium also causes the airways to inflame (swell up), making them narrower than usual. As a result, breathing is made difficult, which causes the 'whoop' sound as you gasp for breath after a bout of coughing.
How whooping cough spreads
Whooping cough is most infectious during the early stages of the condition. The Bordetella pertussis bacterium is carried in droplets of moisture in the air. When someone with whooping cough sneezes or coughs, they propel hundreds of infected droplets into the air. If the droplets are breathed in by someone else, the bacterium will infect their airways.
How to avoid passing on the infection
Whooping cough is highly infectious, so if you or your child have it, it is very important to stay away from others, especially babies, until the bacterium has completely cleared.
The affected person should stay at home until they have:
- completed a course of antibiotics from their GP or
- had intense bouts of coughing (paroxysms) for three weeks
Although bouts of coughing may continue after three weeks, it is unlikely that you will still be infectious because the bacterium will have gone.
See Whooping cough - treatment for more information about antibiotics for whooping cough.
See your GP as soon as possible if you think that you or your child may have whooping cough.
Your GP will usually be able to diagnose whooping cough by asking you about the symptoms and listening to the cough (the whooping cough is very distinctive).
Sometimes, your GP will need to confirm the diagnosis by taking a blood test to check for antibodies to the whooping cough bacterium.
A whooping cough diagnosis can also be confirmed by taking a sample of mucus from the back of the throat with a swab (a small stick similar to a cotton bud) and testing this for the Bordetella pertussis bacterium. However, this method is not always accurate.
If a young baby has suspected whooping cough, they may need to be diagnosed in hospital, where they will be given any necessary treatment. This is because the disease can be severe in babies.
Whooping cough can be treated successfully with antibiotics and most people make a full recovery.
If whooping cough is diagnosed during the first few weeks of the infection, your GP may prescribe a course of antibiotics to prevent the infection spreading further.
Antibiotics will stop you being infectious after five days of taking them. However, without antibiotics, you may still be infectious until three weeks after your intense bouts of coughing (paroxysms) start.
If whooping cough is not diagnosed until the later stages of the infection, your GP may not prescribe antibiotics. This is because the bacterium that causes whooping cough has already gone by this time, so you are no longer infectious. Antibiotics will make no difference to your symptoms at this stage.
Treating babies and young children
Babies are affected most severely by whooping cough, and they are most at risk of developing complications. For this reason, babies under one year of age who contract whooping cough will often need treatment in hospital (see box).
If your child is admitted to hospital to be treated for whooping cough, it is likely they will be treated in isolation. This means they will be kept away from other patients. This is to prevent the whooping cough infection from spreading.
Your child may need to be given antibiotics intravenously (straight into a vein through a drip).
If your child is severely affected, they may also need corticosteroid medication as well as antibiotics. Corticosteroid medication contains steroids. These are powerful hormones that will reduce inflammation (swelling) in your child's airways, making it easier for them to breathe. Like antibiotics, corticosteroids may be given intravenously.
If your child needs additional help with breathing, they may be given extra oxygen through a facemask. A handheld device called a bulb syringe may also be used to gently suction away any mucus that is blocking their airways.
Whooping cough is much less serious in older children and adults than it is in babies and young children. Your GP will usually advise you to manage the infection at home and follow some simple advice:
- Get plenty of rest.
- Drink lots of fluids to prevent dehydration.
- Clear away any excess mucus or vomit during bouts of coughing so it cannot be inhaled and cause choking.
- Stay away from other people until you have completed your course of antibiotics or (if you are not prescribed antibiotics) until you have had intense bouts of coughing (paroxysms) for three weeks.
Even though you or your child may still have bouts of coughing after three weeks, it is unlikely that you will still be infectious.
Severe disease in young babies
Young babies can be severely affected by whooping cough and it can cause significant damage to their lungs. Therefore, they may need a high level of support in hospital, involving:
- ventilation to support their lungs
- intravenous medicine to support their blood pressure
If the above measures fail to work, the baby may need extracorporeal membrane oxygenation (ECMO). This is similar to a heart-lung bypass machine and delivers oxygen into the blood.
Babies and young children
Babies and young children are usually most severely affected by whooping cough. They are most likely to develop severe complications such as:
- pneumonia, an infection that causes inflammation of the tissues in your lungs
- temporary pauses in breathing as a result of severe difficulty with breathing
- weight loss due to excessive vomiting
- seizures or brain damage, which can occur if breathing difficulties prevent enough oxygen from getting to the brain
- low blood pressure, requiring medication
- kidney failure, requiring temporary dialysis
However, these complications are rare.
Severe complications such as pneumonia and brain damage can be fatal, although this is extremely rare and mostly occurs in babies under six months old.
Older children and adults
Older children and adults are occasionally affected by complications of whooping cough. However, the complications are usually much less serious than those experienced by babies and young children.
Less serious complications can include:
- nosebleeds and burst blood vessels in the whites of the eyes from intense bouts of coughing
- bruised ribs as a result of intense coughing
- a hernia (where an internal part of the body, such as an organ, pushes through a weakness in the muscle or surrounding tissue wall) due to intense coughing
- a swollen face
- ulcers on the tongue and mouth
- ear infections such as otitis media (a build-up of fluid in the middle ear)
In Ireland, whooping cough is now uncommon due to vaccination against the bacterium causing it. But it is still very important that babies and young children are vaccinated against whooping cough, because it is still possible for the infection to occur.
The 6-in-1 vaccine
Pertussis can be prevented by vaccination.
The pertussis vaccine is given to children as part of the 6 in 1 vaccine at 2, 4 and 6 months of age. The 6 in 1 vaccine protects against Diphtheria, Hepatitis B, Hib (haemophilus Influenzae B),Pertussis, Polio and Tetanus.
Booster vaccine doses are given at 4-5 years of age (4 in 1 vaccine) which protects against Diphtheria, Pertussis (Whooping Cough), Polio and Tetanus,) and again between 11-14 years of age (Tdap vaccine) which protects against Diphtheria, Pertussis (Whooping Cough) and Tetanus
If your child requires vaccination, or you are unsure of your child’s vaccination status, contact your GP for advice.
The most common side effects that babies experience are:
- pain, redness and swelling at the injection site
- irritability and increased crying
- being off colour or having a fever
If your child has a problem with their immune system, speak to your GP for advice about vaccination. Babies with mild coughs or colds can still have the vaccine.
Some people are considered to be more at risk of developing whooping cough than others, or may be more likely to develop a serious form of the condition. These people include children under five years of age (who may not yet be fully vaccinated) and those who are not vaccinated.
If you think that you or your child may be at risk, see your GP because you may need to take a course of antibiotics to prevent the illness from developing.