Pertussis (whooping cough)

Definition and epidemiology

Pertussis is a highly contagious respiratory tract infection caused by Bordetella pertussis. It spreads by airborne droplets from coughing or sneezing, especially during close contact.

It remains an important cause of illness and death, particularly in infants, despite effective vaccines. Outbreaks are common, and many countries require notification to public-health authorities.

Patients are most infectious and antibiotics are most useful early, especially during the catarrhal stage when symptoms may look like an ordinary viral respiratory infection.

Clinical stages

• Older children and adults may have prolonged cough without classic whoop or paroxysms, but they can still transmit infection.
• Maintain a high index of suspicion when compatible symptoms occur after close contact with a suspected case or during an outbreak.
• New fever during the course can suggest secondary bacterial pneumonia.
• Severe disease and death risk are highest in infants. Older adults, immunocompromised patients, and people with underlying respiratory disease also have increased risk of severe illness and admission.

Complications and admission criteria

• Complications include secondary bacterial pneumonia, dehydration, malnutrition, feeding failure, seizures, encephalopathy, sudden death, intracranial bleeding, petechiae, rib fracture, hernia, and rectal prolapse.
• Admit patients with severe illness such as respiratory distress, apnoea, cyanosis, pneumonia, seizures, or impaired consciousness.
• Admit infants up to 3 months of age for continuous monitoring because of apnoea risk.
• Admit patients who cannot feed or drink adequately, or who require nasogastric feeding, IV fluids, oxygen, or close respiratory support.

Antibiotic treatment

Start antibiotic treatment as soon as pertussis is suspected when treatment criteria are met. Antibiotics reduce transmission and are most beneficial early.

• Use co-trimoxazole only when macrolides are contraindicated, not tolerated, or unavailable.
• Avoid co-trimoxazole in the first trimester of pregnancy, after 36 weeks of pregnancy, and in breastfeeding of neonates or premature, low-birth-weight, jaundiced, or ill infants because of haemolysis and jaundice risk.
• Warn patients to seek urgent care for anaemia or jaundice, especially where G6PD deficiency is common.

Infection prevention and control

• Patients are considered infectious until they have completed 5 days of appropriate antibiotics. If untreated, infectiousness continues until 21 days after onset of paroxysmal cough.
• In hospital, use a single room if possible or cohort pertussis cases away from other patients. Apply standard and droplet precautions; the patient should use cough etiquette and a surgical mask when outside the room if age and condition allow.
• During the infectious period, avoid contact with young children and pregnant women, and avoid childcare, school, work, and other congregate settings.
• Report suspected cases according to local or national public-health rules.

Supportive care

• Continue breastfeeding. Provide frequent small feeds, including after coughing bouts and post-tussive vomiting, to maintain fluid and calorie intake.
• Some patients need nasogastric feeding or IV maintenance fluids. Nasogastric tube placement can trigger coughing paroxysms, so it should be done by experienced staff with minimal manipulation.
• If weight loss occurred, consider nutritional supplementation during convalescence when the child can eat comfortably.
• Place the patient semi-reclined at about 30 degrees. In apnoea, stimulate the patient and be ready to ventilate; keep bag and mask accessible.
• Give oxygen for SpO2 below 92%, severe respiratory distress, or recurrent apnoea. Use gentle oropharyngeal suction only when needed and avoid deep suctioning because it can provoke coughing.
• For outpatient children, teach caregivers to seek immediate care for respiratory difficulty, apnoea, cyanosis, increasing fever, seizures, impaired consciousness, dehydration, or feeding difficulty.

Contacts and post-exposure prophylaxis

• Post-exposure prophylaxis uses the same antibiotic regimens as treatment and is recommended regardless of vaccination status for eligible contacts.
• Give prophylaxis to asymptomatic close contacts of a suspected pertussis case within 3 weeks of onset of paroxysmal cough.
• Give prophylaxis to asymptomatic exposed people at high risk of complications, and to people who will come into contact with high-risk people.
• High-risk groups include pregnant women in the third trimester, infants under 1 year, people with immunodepression, people with moderate to severe asthma, and, depending on local assessment, people with other respiratory disease or adults 65 years and over.
• Isolation of asymptomatic contacts is not required. Symptomatic contacts should be treated as suspected pertussis.

Prevention, vaccination, and handover

• Pertussis vaccination gives substantial protection, but immunity wanes over time. Begin or refer for vaccination in suspected cases and contacts who are not up to date.
• Routine schedules use a 3-dose primary series of pertussis-containing vaccine from 6 weeks of age or according to national protocol, with a booster preferably during the second year of life. Interrupted primary series should be completed rather than restarted.
• Moderate or severe acute illness generally delays vaccination, but vaccination should be given as soon as the patient improves. Vaccination does not replace post-exposure prophylaxis for someone already exposed or infected.
• Handover should include age, pregnancy status where relevant, vaccination history, onset of cough and paroxysms, apnoea/cyanosis, feeding and hydration status, oxygen saturation, complications, antibiotic eligibility and regimen, IPC measures, close contacts, prophylaxis plan, and notification status.