Overview
Whooping cough (pertussis) is a highly contagious bacterial respiratory infection caused by Bordetella pertussis. It causes severe prolonged coughing fits followed by a characteristic whooping sound when breathing in. It can be life-threatening in young infants. Vaccination is the primary prevention but immunity wanes, causing outbreaks even in vaccinated populations.
How common is it?
Whooping cough remains common globally despite vaccination. In the UK, cyclical outbreaks occur every 3 to 4 years. Cases declined dramatically with vaccination but periodic outbreaks still affect thousands each year.
Causes and risk factors
Bordetella pertussis attaches to the cilia of the respiratory tract, releasing toxins that cause inflammation and impair mucociliary clearance, leading to severe, prolonged coughing.
Common risk factors
- Exposure to infected persons (droplet and contact transmission)
- Waning immunity after vaccination or previous infection
- Unvaccinated or incompletely vaccinated status
- Young infants under 3 months (most vulnerable — not yet fully vaccinated)
Symptoms
- Stage 1 (catarrhal, 1 to 2 weeks): symptoms resembling a cold — runny nose, mild cough, low fever
- Stage 2 (paroxysmal, 2 to 6 weeks): severe coughing fits of up to 20 coughs per breath, often followed by a high-pitched whoop on inspiration, vomiting after coughing, and cyanosis in infants
- Stage 3 (convalescent, weeks to months): gradual decrease in coughing
- Infants may not whoop — they may simply stop breathing (apnoea)
- Adults and vaccinated individuals: prolonged cough without classic features (often missed)
When to see a doctor
Seek emergency help for any infant with apnoea (stopping breathing), cyanosis (going blue), or severe breathing difficulty. See a GP for cough lasting more than 3 weeks, or if a family member has been in contact with a confirmed case.
Diagnosis
Nasopharyngeal swab for Bordetella culture or PCR (most sensitive in the first 2 weeks). Serology (pertussis IgG) in later stages. Blood count: marked lymphocytosis is characteristic.
Treatments
Antibiotics
Azithromycin 5-day course or clarithromycin for 7 days is the treatment of choice. Antibiotics reduce infectiousness if given early but do not significantly shorten symptom duration once paroxysmal stage begins. All close contacts should receive prophylactic antibiotics regardless of vaccination status.
Supportive care
Hospitalisation for young infants, those with severe disease, or infants who stop breathing. Oxygen, feeding support, and monitoring. Avoid cough suppressants (ineffective). Rest and fluids.
Isolation
Isolate from others until 48 hours after starting antibiotics (or 21 days from onset of cough if untreated) to prevent spread.
Self-care and lifestyle
- Isolate coughing individuals promptly when whooping cough is suspected
- Ensure all household contacts receive antibiotic prophylaxis
- Young infants should be kept away from coughing contacts as much as possible
Prevention
DTaP-IPV-Hib-HepB vaccination at 8, 12, and 16 weeks provides primary protection. Booster at 3 to 4 years. Maternal pertussis vaccination (Tdap) at 16 to 32 weeks of pregnancy transfers antibodies to the newborn, protecting them in the first weeks of life before they can be vaccinated. This is the single most effective protection for very young infants.