Overview

Infections and chronic illnesses happen all over the globe. They can range from simple common cold infections to more serious ones like tuberculosis. Some may have experienced or heard about whooping cough, and in this article, we will discuss what it is, how it occurs and its outbreaks.

So, what is whooping cough, also known as pertussis? It is an infectious disease that affects the respiratory tract and can spread easily. It is mainly caused by the bacterium Bordetella pertussis.¹ 

This illness can affect anyone, but it is more severe and fatal in infants, older children/adults can also have a severe form of this disease, especially if they have pre-existing medical conditions.¹ 

Pertussis

Overview

As mentioned above, the causative agent is Bordetella pertussis. This is a small gram-negative bacterium that can cause the disease through toxins.¹ They are aerobic coccobacilli that produce pertussis toxin, adenylate cyclase toxin and haemolysin.² 

It causes an acute respiratory infection with intense spasmodic cough episodes.² It is also associated with marked lymphocytosis.² Around 60% of the cases of whooping cough occur in adults and adolescents, but the highest mortality rates occur in infants below the age of 2 months.³ Before vaccinations, the U.S. had recorded around 270,000 cases with up to 10,000 deaths.⁴ It is also worth noting that both natural immunity from a previous infection and vaccinations do not provide life-long immunities, hence the cases of pertussis are on the rise in developed countries (among other causes).⁵ 

Bordetella pertussis has multiple mechanisms affecting our bodies. They do not invade submucosal cells or go to the bloodstream, but their toxins can have a systemic effect and inhibit our immune responses.⁴ Table 1 shows the summary of key components that are important for Bordetella pertussis.

Table 1. Essential components of Bordetella pertussis ⁴ 

Transmission

The transmission of the whooping cough occurs from person to person through droplets when sneezing and coughing.⁴ 

Symptoms

Symptoms after initial infections can develop within 5 to 10 days, and sometimes take up to 3 weeks. There are 3 stages for the symptoms:²

1. Stage 1 is defined as the early symptoms stage and can last for 1-2 weeks. Infected individuals are highly contagious, and symptoms include a runny or stuffy nose, fever and mild occasional coughing
2. Stage 2 is defined as the later symptoms stage, and it takes place 1-2 weeks after initial symptoms. In this stage, patients develop paroxysms which are coughing fits that usually last 1 to 6 weeks but sometimes can last up to 10 weeks. People may have other symptoms along with the cough, like a high-pitched ‘whoop’ during inhalation after coughing, struggling to breathe, difficulty sleeping, fatigue, vomiting during or after coughs, and even fracturing a rib
3. The recovery stage lasts around 2-3 weeks up to a month. It is a slow process with the symptoms slowly reducing over time. However, the coughing fits may return months after the initial illness

Complications

Complications can occur in babies and children, and present a serious threat to their health and in some cases can be deadly.⁶ 

• Babies may struggle to breathe and have apnoea, which is a life-threatening pause in breathing. This can affect 2 in 3 babies (around 68%) 
• Pneumonia, and affects 1 in 5 (22%) 
• Convulsions, which are violent and uncontrolled shaking (2%) 
• Encephalopathy in 1 in 150
• Death in 1 in 100 (1%) due to the complications

Diagnosis

There are multiple ways to test for whooping cough:²

• Nasopharyngeal swabs or aspirate: This is done to take samples of the bacteria and test for their presence through culture (which is the golden standard) or PCR 
• Blood/serology tests to measure antibodies against pertussis toxins 

Treatment

Treatment of whooping cough includes:

• Supportive care such as hydration, eating small meals every couple of hours to avoid vomiting, avoiding dust and smoke that can cause coughing, and the use of clean, cool mist humidifiers to help the cough 
• Taking medication (antibiotics) as prescribed by a healthcare provider 
• More severe cases might require hospitalisation

Factors that influence pertussis outbreaks

Multiple factors can affect pertussis and its outbreaks such as:

Vaccine factors

As mentioned, natural immunity and vaccines do not provide life-long protection and can wane over time, causing the infection to resurface. Additionally, every country operates differently in vaccinations, thus, they will have different rates.³ 

Human behaviour

There are multiple steps that we take as humans, that can affect our health, and this includes infections. Travelling to and from areas with pertussis outbreaks can lead to infection and its spread. Additionally, lack of awareness of the illness can play a role in more cases (for example, mistaking pertussis for other respiratory conditions or other infections), as well as vaccination choices, such as hesitance or refusal to vaccinate. 

Bacterial mutation

Mutation and evolution of whooping cough can occur such that it becomes resistant to current vaccines, which necessitates the need for new effective treatments.⁷ 

Recent pertussis outbreaks

Pertussis is a cyclical disease that can peak every 3-5 years. There was a major pertussis outbreak in the United Kingdom in 2012, but after the introduction of maternal vaccination in 2012, the cases fell in numbers. However, an increase in occurrence in 2016 has been noted. 

In more recent times, after the introduction of the pertussis vaccine in pregnancy, there have been 29 confirmed baby deaths (all of them were too young to be fully protected by infant vaccination) from 2013 to 2024 in the UK. 23 of these 29 infants had mothers who were not vaccinated in pregnancy. 

Maternal vaccination is very effective against pertussis illness and hospitalisation. Hence, taking appropriate measures and steps are crucial for a safe pregnancy, delivery, and a healthy baby.

Prevention

There are some steps that we can take to prevent the spread and infection with pertussis:

• Vaccination using the recommended guidelines 
• Screening for pertussis more regularly 
• Maintaining good hygiene to lower the chances of infection 
• Preventative antibiotics, also known as postexposure antimicrobial prophylaxis. This is given to people exposed to the bacteria to help avoid the sickness. People who are around someone with pertussis can take this to avoid getting sick 

FAQs

What are the survival rates of pertussis?

Most infections result in full recovery, however, the recovery process can take a long time (can be several months).⁶ 

How rare is pertussis?

24.1 million cases of pertussis occur worldwide every year, with around 160,700 deaths occurring in children (< 5 years old). 

Summary

Pertussis, or whooping cough, is a highly contagious respiratory tract illness that can affect anyone but is more serious, and deadly in babies and infants. Pertussis remains a significant health concern as cases are rising and there is no life-long immunity for it. Hence, having the right treatment and vaccination plans for this disease can help to improve the health of individuals and their quality of life.