Whooping cough
Exam Tips
- Classic OSCE pattern: prolonged cough with paroxysms, post-tussive vomiting, minimal fever, and household spread; whoop may be absent in infants/adults.
- Infants can present with apnoea and cyanosis before a classic whoop appears, so maintain high suspicion in unvaccinated young babies.
- Test choice depends on timing: PCR/culture are most useful within 21 days; serology/oral fluid IgG are more useful later in selected age groups.
- Pertussis is notifiable in the UK: remember public health notification and contact management alongside individual treatment.
- Vaccination is central to prevention: maternal vaccination protects newborns before primary infant doses.
- For revision diagrams, review a standard three-phase pertussis timeline figure in your paediatrics/infectious diseases textbook (catarrhal -> paroxysmal -> convalescent).
Definition
Whooping cough (pertussis) is a highly contagious respiratory infection, usually caused by Bordetella pertussis, transmitted by droplets from coughing/sneezing and occasionally contaminated secretions. It classically causes a prolonged paroxysmal cough illness (catarrhal, paroxysmal, then convalescent phases), with greatest severity and mortality in young infants, especially before primary immunisations are complete.
Pathophysiology
Bordetella pertussis attaches to ciliated respiratory epithelium via adhesins (including filamentous haemagglutinin, pertactin, and fimbriae), then releases toxins that drive disease. Pertussis toxin ADP-ribosylates inhibitory G-proteins (Gi), increasing intracellular cAMP and contributing to lymphocytosis and immune dysregulation, while tracheal cytotoxin and other factors impair ciliary clearance and damage epithelium. The result is mucus retention and hypersensitive cough reflex, producing repetitive cough paroxysms with inspiratory gasps ('whoop'), post-tussive vomiting, and in infants apnoea/cyanotic episodes. Immunity after infection or vaccination wanes over time, so reinfection can occur and may present atypically.
Risk Factors
- Age under 6 months (highest risk of severe disease, complications, and death)
- Incomplete or absent pertussis vaccination
- Maternal non-vaccination in pregnancy (reduced passive neonatal antibody protection)
- Household or close-contact exposure to a confirmed/suspected case
- Waning vaccine-derived immunity in adolescents and adults
- Pre-existing chronic lung disease or frailty in older adults (higher morbidity)
Clinical Features
Symptoms
- Catarrhal phase (1-2 weeks): rhinorrhoea, mild cough, sore throat, malaise, conjunctival irritation, usually little/no fever
- Paroxysmal phase (1-6 weeks, can be up to 10): severe repetitive coughing fits, often nocturnal
- Inspiratory whoop after coughing burst (may be absent in infants and adults)
- Post-tussive vomiting
- Apnoeic episodes in young infants (sometimes without obvious whoop)
- Convalescent phase (2-3 weeks): gradual improvement, but cough can recur with later viral infections for months
Signs
- Paroxysmal cough observed during consultation or history from carers
- Cyanosis or desaturation during severe coughing episodes (especially infants)
- Facial flushing/sweating during paroxysms; occasional cough syncope in adults
- Subconjunctival haemorrhage, petechiae, or facial oedema from raised intrathoracic pressure
- Minimal or absent pyrexia despite marked cough illness
Investigations
Management
Lifestyle Modifications
- Advise rest, hydration, and small frequent feeds if vomiting follows cough; monitor infants closely for apnoea, cyanosis, poor feeding, and dehydration.
- Reduce transmission: droplet/respiratory hygiene and avoid close contact with vulnerable infants.
- Exclude from nursery/school/work for 48 hours after starting appropriate antibiotics, or for 21 days from cough onset if untreated.
- Urgent hospital assessment/admission for young infants, apnoea, cyanosis, respiratory distress, inability to maintain hydration/nutrition, or suspected complications.
- Check and update immunisation status of child and household contacts; reinforce maternal vaccination in pregnancy (ideally 16-32 weeks, can be offered later).
Pharmacological Treatment
Macrolide antibiotics for treatment (best started early; also used for post-exposure prophylaxis in high-risk contacts)
- Azithromycin oral: 1 month-17 years 10 mg/kg once daily for 3 days (max 500 mg daily); adults 500 mg once daily for 3 days
- Clarithromycin oral: 1 month-11 years 7.5 mg/kg twice daily for 7 days (max 500 mg per dose); 12-17 years and adults 500 mg twice daily for 7 days
- Erythromycin oral (alternative): children 40-50 mg/kg/day in divided doses for 14 days (max 2 g/day); adults 250-500 mg four times daily for 14 days
Antibiotics reduce infectivity and may modify illness if started in catarrhal/early paroxysmal phase; late treatment mainly limits transmission. Safety: macrolides can prolong QT interval and interact with other QT-prolonging/CYP3A4 drugs; clarify interaction history. Clarithromycin is generally avoided in pregnancy unless benefits outweigh risks; azithromycin/erythromycin are usually preferred in pregnancy. In neonates, monitor for infantile hypertrophic pyloric stenosis risk with macrolide exposure.
Symptom control/supportive prescribing
- Paracetamol oral: 1 month-2 months 60 mg every 4-6 hours (max 4 doses/24 h); 3 months-5 years 15 mg/kg every 4-6 hours (max 4 doses/24 h); 6-15 years 250-500 mg every 4-6 hours (max 4 doses/24 h); adults 500 mg-1 g every 4-6 hours (max 4 g/day)
No strong evidence for routine antitussives in children; avoid codeine-containing cough preparations in under-12s and use caution in adolescents with respiratory compromise.
Complications
- Apnoea (especially young infants)
- Secondary bacterial pneumonia
- Seizures
- Cerebral hypoxia with potential neurological injury
- Encephalopathy (rare, more severe disease)
- Otitis media
- Subconjunctival haemorrhage, epistaxis, facial oedema, petechiae
- Pneumothorax
- Rib fracture
- Umbilical/inguinal hernia or rectal prolapse from repeated high intrathoracic/intra-abdominal pressure
- Urinary incontinence
- Dehydration, malnutrition, and weight loss due to recurrent post-tussive vomiting
Prognosis
Prognosis is usually good in older children and adults, although cough can persist for weeks to months and relapse with intercurrent viral illness. Infants (particularly under 6 months, and highest risk under 2 months) have much higher rates of hospitalisation, severe complications, and death; case fatality is around 1% in the youngest infants. Prior vaccination or previous infection often attenuates severity but does not confer lifelong protection.
Sources & References
✅NICE Guidelines(1)
- Whooping cough[overview]
📖Textbook References(20)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 327, 328)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 562, 563)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 29, 30, 31)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 195)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 28, 29)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 562, 563)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 1055)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 1055)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 470)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 1055)[context]
- Guyton and Hall Textbook of Medical Physiology (John E. Hall, Michael E. Hall) (Z-Library).pdf(pp. 470)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 465, 466)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 405, 406)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 396)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 396, 397)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 406)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 395, 396)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 465, 466)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 885, 886)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 886)[context]