Introduction

Pertussis, commonly known as whooping cough, is an infection of the breathing tubes that supply the lungs (the bronchial tree). It spreads very easily and can be very serious.¹

The danger it poses to young babies is well documented,² but children aged 11 to 18 years are also at risk as their immunity from childhood vaccinations begins to fade.^2,3 Between January and May 2024 in the UK, most cases of pertussis (53.4%, 4,057) were diagnosed in children aged 15 years or older.⁴

Because of this, it is important that we understand how pertussis is transmitted amongst older children and teenagers and what can be done to prevent it from spreading. 

Causes of pertussis

Pertussis is caused by a type of bacteria called Bordetella pertussis. These bacteria produce cytotoxin which damages the lining of the airways, leading to the symptoms of whooping cough.⁵ 

How does pertussis spread?

Pertussis is spread via mucus droplets from an infected person, normally produced during a cough or sneeze (like an aerosol being sprayed).⁷ These droplets can then be inhaled by anyone else nearby, allowing the infection to spread to a new person.

Although being near someone coughing/sneezing is the most common way for the infection to spread, being nearby and sharing personal items can also increase the risk of infection. This is because the bacteria can live for several days outside the human body.⁸ 

Once a person has been infected, their symptoms take around 7-10 days to start showing, and they are most infectious around 3 weeks after the coughing has started.⁹

What are the symptoms and how do they progress?

There are 3 stages, as follows:

Stage 1

Catarrhal stage lasts 1-2 weeks: This stage is often mistaken for a common cold, but the cough begins to get worse.

Symptoms include:

• Runny nose
• Sneezing
• A low-grade fever
• An occasional, mild cough

Stage 2

Paroxysmal stage lasts 4-8 weeks: The cough becomes more severe. There are extensive coughing fits that can be followed by a high-pitched ‘whoop’, from which the disease gets its colloquial name 'whooping cough’. The ‘whoop’ is from the person attempting to catch their breath. In more serious cases, the person will turn blue and vomit mucus or food. They may also have brief periods when they stop breathing.

Stage 3

Convalescent stage lasts weeks to months depending on the individual: This is the recovery phase as the person slowly starts to get better. The coughing fits may return if they get another respiratory illness.⁶

Why are teens at risk?

Social Interactions

Teenagers often engage in social behaviours that involve close physical contact, such as attending school, participating in sports, and going to social gatherings. Although these interactions are very important for their quality of life, they also provide an ideal opportunity for the bacteria to spread.

Vaccination Status

A pertussis vaccine is one of the first vaccines a baby is given and provides good protection against the infection.¹⁰ However, as children age their level of immunity decreases, leaving them vulnerable once again.¹¹ There has also been an increase in the number of children who have not received the vaccine at all due to hesitancy among parents/guardians.¹²

Awareness and Health Practices

Although a lot of people know what pertussis/whooping cough is, not all can recognise the early symptoms or are aware of how often teenagers are affected. This is true for not only the general public but healthcare professionals as well.¹³ In addition, poor respiratory hygiene, such as not covering the mouth/nose while coughing or sneezing, makes it much easier for infections like pertussis to spread. 

Diagnosis and challenges

How is pertussis diagnosed?

In its early stages, pertussis has few distinguishing features. This makes it difficult to initially diagnose as the symptoms are similar to other respiratory conditions. However, as the disease progresses, the characteristic ‘whooping’ sound made after a bout of coughing can allow a doctor to make a diagnosis as part of a clinical exam and medical history.¹⁴

To confirm the diagnosis, the doctor may wish to undertake a laboratory test for the pertussis bacteria. There are several methods available for this:

• Bacterial culture: a nose/throat swab is taken. Bacteria from this are grown on an agar plate until the colony is large enough for laboratory scientists to identify the species.
• A PCR test (polymerase chain reaction): if the swab for this test picks up even a tiny amount of bacterial DNA it can be used to identify pertussis. A PCR artificially multiplies the DNA in a sample so it is easier to identify the species. 
• Serology: a type of blood test which can be used to look for antibodies to the pertussis bacteria
• OFT (an oral fluid (saliva) test): This is available to older teens and is used to look for an immune response to pertussis.¹⁵ 

What can make diagnosis difficult?

Because the early symptoms of a pertussis infection are so similar to those of the common cold, it can be easy for a healthcare professional to misdiagnose the condition, or for there to be a significant delay in the patient being brought in for a consultation by their parent/guardian. 

Prevention strategies

There are a few different ways that these issues can be addressed to combat the spread of pertussis in teens: 

Vaccinations

Taking babies for their full course of vaccines will help reduce the overall number of cases in the population and is therefore an important way to slow the spread of the disease. Healthcare workers have an important role in addressing any concerns a parent may have about vaccinating their child and helping them understand the importance of doing so.¹⁶ Eligible teenagers should be given pertussis booster shots, as this can have a significant impact on the number and severity of cases if an outbreak occurs.¹⁷ However when this is offered does vary depending on where you live, so check with your country's health authority for the most appropriate guidance.

Hygiene practices

The recent COVID-19 pandemic showed us all the importance of safe hygiene practices when it comes to preventing the spread of respiratory illness. The same measures will help combat pertussis transmission. Washing hands more frequently and for longer, covering nose and mouth when coughing/sneezing, and avoiding close proximity to others whilst you have symptoms are all basic steps that teenagers can be encouraged to take.¹⁸

Public awareness

Educating parents and teenagers (and the public in general) about pertussis symptoms and the importance of vaccination can increase early diagnosis and improve vaccination rates – both of which can help reduce transmission.¹⁹ If there is a larger outbreak then this increased awareness would help with any contact tracing that may be required to limit the spread.²⁰

Summary

Pertussis, or whooping cough, spreads among teenagers primarily through coughing or sneezing. Factors which make this age group more vulnerable include waning immunity from childhood vaccination and close social interactions in schools and gatherings. Poor respiratory hygiene, difficulty diagnosing in the early stages, and not completing a course of childhood vaccinations increases the number of pertussis cases in the population as a whole, which also has an impact on the number of teenagers suffering from it. 

Simple and effective steps can be taken to combat this. Increasing vaccine uptake and improving respiratory hygiene standards are both very achievable goals. Alongside this, increasing awareness of the infection – both amongst both the public and healthcare professionals – can help achieve a prompt diagnosis and an appropriate response.