What Is Whooping Cough?

Overview

Whooping cough, also known as pertussis, is a common and highly contagious bacterial infection of the respiratory system.¹ It is characterised by the “whoop” sound which is produced during sharp intakes of breath following violent and recurrent coughing bouts.² Whooping cough is a notifiable disease in the UK and should be reported to the local Public Health England (PHE) centre within 3 days of suspicion. The main means of transmission is through airborne droplets, for example, when an infected person coughs or sneezes. The incubation period is 1 to 3 weeks.² It is an extremely contagious infection and can result in life-threatening complications, especially in young children. Furthermore, though it is a vaccine-preventable disease, this protection tends to decline over the years.² 

Causes of whooping cough

Whooping cough is caused by bacteria from the Bordetella species. The commonest types in humans are Bordetella pertussis and, less commonly, Bordetella parapertussis. However, immunocompromised persons are prone to a third type of Bordetella known as Bordetella bronchiseptica which is mainly found in animals.² 

Signs and symptoms of whooping cough

The clinical presentation of whooping cough typically occurs in three phases. 

The first phase catarrhal phase

This is the most infectious phase and lasts 1 to 2 weeks.² In this phase, whooping cough begins as a mild upper respiratory infection with symptoms such as 

• Runny nose
• Conjunctivitis 
• Sore throat 
• Sneezing 
• Mild cough
• Fever

The second phase paroxysmal phase

The cough increases in frequency and severity before gradually subsiding over several weeks. These bouts of coughs, which may produce mucus, occur so fast and violently that the individual is unable to take a breath and is immediately followed by the characteristic whoop sound, cyanosis and vomiting. These events are collectively referred to as paroxysms, and when they occur successively several times within a few minutes, the individual is left exhausted, though they appear normal between paroxysms. Paroxysms are worse at night and can be induced by stimuli such as eating, cold, noise, laughing, or crying.

The third phase convalescent phase 

The residual cough persists for weeks to months and is usually triggered by exposure to another upper respiratory infection or irritant.

Whooping cough can spontaneously resolve in most untreated persons within 3-4 weeks after cough onset, though the bacteria can persist for 6 weeks or more. Thus, it is recommended that infected persons and persons who are not fully vaccinated should self-isolate from work, school, daycare, and public settings until they have received at least 5 days of treatment.¹

Diagnosis of whooping cough

A high index of suspicion should always be maintained. Pertussis should be suspected if a patient presents with a cough lasting 2 or more weeks associated with one or more of the following symptoms: paroxysms of coughing, inspiratory whoop, post-tussive vomiting, or apnea (repetitive breathing interruptions during sleep in infants aged < 1 year).⁴ Pertussis should also be suspected if an individual is exposed to a confirmed case.³ However, because some respiratory illnesses can mimic pertussis and clinical presentation can vary, the diagnosis should be confirmed with laboratory tests.³

Culture and isolation

Culture and isolation of Bordetella pertussis (from nasopharyngeal aspirate or nasopharyngeal swab) is the gold standard as it is highly specific in identifying pertussis. The test is recommended for all ages as long as the time since the cough started is less than 21 days.

Polymerase chain reaction 

Polymerase chain reaction (PCR) test detects DNA sequences and is also recommended in all ages with a duration of cough less than 21 days. This test is more sensitive than culture as it does not require viable (live) bacteria in the specimen. As such, PCR should always be done to complement culture (if in the early stage) and serology (if in the late stage).⁵

Serology test

Serology detects antibodies to the pertussis toxin. It is suitable for older children (over 16 years old), for individuals who have had a cough for more than 14 days and for individuals who received the most recent dose of the whooping cough vaccine (including any dose administered in pregnancy) at least one year before the test. 

Oral fluid testing

Oral fluid testing (OFT) is also used to detect antibodies to the pertussis toxin and is done for clinically suspected patients who are between 2-17 years of age, who have had a cough for more than 14 days and who have NOT received a pertussis vaccine in the past year. However, as it takes time to receive the results, these persons will then be started on treatment. 

Other tests

Checking the levels of white blood cells (leukocytosis and lymphocytosis), especially during the late catarrhal and early paroxysmal phases, it may also predict a fatal outcome in children admitted to the hospital. A chest x-ray may be required.²

Management and treatment for whooping cough

• Treatment includes bed rest, oxygen, suctioning (to clear the mucus from the airway), paracetamol (for fever), adequate fluid intake, and nutrition.²
• Strict isolation is also important while the patient remains infectious, usually during the catarrhal phase and for 21 days after the onset of the paroxysmal phase.²
• If the patient is seen during the first 21 days, antibiotics (macrolides) like azithromycin, clarithromycin or erythromycin are prescribed based on the patient. 
• In the UK, the recommendation is to start the antibiotics within 7–14 days of symptom onset, though this can be tricky if patients present late or there are delays in diagnosis.
• Antibiotics are more effective when given in the catarrhal phase since the primary goal of treatment is to decrease the carriage and spread of disease. In patients treated with antibiotics, isolation should be continued for at least 5 days after treatment is initiated ² 
• Patients should be hospitalised if there are complications, if they are infants who are not fully vaccinated or if they are unable to tolerate oral hydration and nutrition ²

Complications of whooping cough

The major complications can be:¹  

• Pulmonary (e.g. bronchopneumonia)
• Neurological (e.g. brain damage due to cerebral hypoxia, breathlessness during the coughing spells or apnoea)
• Nutritional (e.g. nutritional deficiencies and weight loss due to repeated vomiting) 

When severe, complications can result in permanent disability or death.

Minor complications include:¹

• Subconjunctival haemorrhages 
• Nosebleeds 
• Facial oedema (swelling) 
• Oral ulcers 
• Suppurative otitis media 

The most common reasons for hospitalisation in all ages are severe paroxysms, post-tussive cyanosis, post-tussive vomiting, apnoea, pneumonia, and seizures.⁶

Prevention of whooping cough

Vaccination 

The World Health Organization recommends pertussis vaccine for infants and young children.¹ 

In the UK, the whooping cough vaccine is routinely given as part of the 6-in-1 vaccine to babies at 8, 12 and 16 weeks and 4-in-1 pre-school booster to children aged 3 years 4 months]. In addition, it is given as part of the maternal vaccination programme to pregnant individuals, usually between 16 and 32 weeks (it has no effect on the foetus). However, as the protection from the vaccine reduces with time, the CDC also recommends another single booster dose (Tdap) for all adults to reduce transmission to children.

Other preventive measures 

Other preventive measures include isolating from nursery, school, or work until five days after starting antibiotic treatment or three weeks after the coughing bouts started (whichever is sooner), regularly washing hands with soap and water and covering the mouth and nose with a tissue when coughing and sneezing and properly disposing of used tissues immediately.

FAQs

Is whooping cough contagious?

Whooping cough is a highly contagious infection that is mainly spread through airborne droplets such as when an infected person coughs or sneezes. If untreated, persons with whooping cough remain contagious for 21 days following the onset of cough.

Who are at risk of whooping cough?

High-risk individuals include those with impaired immune responses (such as unimmunized individuals, pregnant individuals and people living with HIV/AIDS), children (especially those less than 3 months old ), and health workers. Other risk factors are climate (peaks during summer), poor nutritional status, and close contact with an infected individual (such as living in the same house or areas of high density).^2,7

How common is whooping cough?

Prior to the development of the pertussis vaccine, whooping cough was a leading cause of infant morbidity and mortality.²  Whooping cough is endemic worldwide, with periodic epidemics occurring every 2-5 years. It is estimated that there are 24 million cases reported annually among children worldwide, of which over 160,000 deaths occur in those under 5 years. 

There were 4341 and 2947 laboratory-confirmed cases of pertussis reported in 2017 and 2018 in England, respectively. However, a recent report by the UK Health Security Agency (UKHSA) revealed a significant decline, likely due to the impact of COVID-19 measures. According to the report, in the first quarter of 2022, there were 9 laboratory-confirmed cases of whooping cough in England, of which there were no cases in children aged 0-3 months old and 3–11 months, while 2 cases occurred in children aged 1–4 years, and 7 in people aged 15 years or older.

When should I see a doctor?

Whooping cough is a highly contagious infection and notifiable disease so a high index of suspicion should be maintained.

You should see your GP if:

• Your baby is under 6 months old and has symptoms of whooping cough
• You or your child have a very bad cough that is getting worse or lasted more than three weeks
• You are pregnant and have been in contact with someone with whooping cough
• You or your child has a weakened immune system and has been in contact with someone with whooping cough

You go to your nearest accident and emergency (A&E) department if:

• You or your child have significant breathing difficulties, such as long periods of breathlessness, shallow breathing, or apnoea
• You or your child develop signs of serious complications of whooping cough, such as fits (seizures) or chest pain that's worse when breathing or coughing.
• You or your child's lips, tongue, face, or skin suddenly turn blue or grey 

Summary

Whooping cough, also known as pertussis, is a highly contagious bacterial infection of the respiratory system, characterised by a “whoop” sound which is produced during forced inspiration after rapid bouts of violent coughing. Whooping cough is a notifiable disease in the UK and should be reported to the local Public Health England (PHE) centre within 3 days of suspicion. Symptoms typically progress through three phases. Pertussis should be suspected if a patient presents with a cough lasting 2 or more weeks associated with one or more symptoms of pertussis. This is confirmed with laboratory tests. The NHS recommends pertussis vaccine for infants, young children and pregnant individuals. If suspect that you or your loved ones might have pertussis, visit the ER immediately.