Whooping cough (Pertussis) Flashcards
Define whooping cough.
A respiratory tract infection characterised by paroxysms of coughing followed by a ‘whoop’ (sudden massive inspiratory effort against a narrowed glottis).
Explain the aetiology/risk factors of whooping cough.
Caused by the bacterium Bordetella pertussis; has an incubation period of 7-10 (up to 21) days, and is communicable for 3 weeks from start of coughing via droplet spread.
Summarise the epidemiology of whooping cough.
Incidence England and Wales: 594/year (2005). Immunisation has decreased the risk of developing whooping cough by 80-90%. Previously, epidemics occurred in the UK every 4 years.
Peak age: 3 years. In infants < 6 months, it has a much higher mortality.
What are signs and symptoms of whooping cough?
Catarrhal stage: Duration 1-2 weeks; indistinguishable from common URTIs with nasal congestion, rhinorrhea, sneezing, low-grade fever and the occasional cough. At this stage pertussis is most infectious.
Paroxysmal stage: Duration 1-6 weeks; consists of paroxysms of coughing, following in the older child by a ‘whoop’, with associated vomiting, dyspnea and possibly seizures. Infants < 6months don’t have the characteristic whoop but may have apneic episodes.
Convalescent stage: Duration weeks to months; chronic cough that becomes less paroxysmal.
Older children and adolescents: May not exhibit distinct stages. Symptoms in these patients include uninterrupted coughing, feelings of suffocation or strangulation, and headaches.
What are appropriate investigations for whooping cough?
Bloods: Increased WCC, absolute lymohocytosis is common, increase CRP and U&E.
Immunocytochemistry: Direct fluorescent antibody testing of pernasal swabs.
What is the management of whooping cough?
Immunisation is key
Prophylaxis: Erythromycin may be used in the catarrhal phase to decrease contagiousness of an individual or prophylactically to siblings/close contacts of a case of pertussis, especially if <1 year of age and not fully immunised.
Respiratory isolation: 5 days after starting antibotics or until 3 weeks after the onset of the coughing spams if the person is not receiving antibiotic treatment.
What is the criteria for admission with whooping cough?
Criteria for admission:
Age < 6 months due to increase mortality in this age group
Vomiting with dehydration or weight loss
Respiratory distress +/- cyanosis
Apnoea associated with paroxysms
Notifcation: Whooping cough is notifiable disease (CCDC)
What are complications associated with whooping cough?
Paroxysmal cough: May cause petechiae and conjunctival haemorrhages. Lack of intake may cause dehydration and weight loss.
Seizures (3%): If encephalopathy follows, one-third die, one-third remain neurologically impaired, one-third recover fully.
Secondary infections: Otitis media, bronchiectasis, pneumonia (main cause of pertussis-related deaths).
What is the prognosis of whooping cough?
Usually lasts 6-8 weeks; however, a prolonged illness may occur (100-day cough). There is significant morbidity and mortality in infants < 6 months in whom apnoea associated with paroxysms may cause sudden death.
