Whooping Cough

Question 1

Definition of whooping cough

Answer 1

A highly infectious notifiable disease caused by the bacterium Bordetella Pertussis- produces pertussis toxin which drives the pathogenesis of the disease (Bordatella parapetusis causes a similar illness, but does not produce any toxins so the disease is usually milder and shorter.)

Question 2

Key characteristic of whoping cough

Answer 2

The name is derived from the characteristic ‘whoops’ that occur in children- caused by sharp inhalation of breath during bouts of paroxysmal cough.

Question 3

How can whoopign cough present differentl in infants

Answer 3

• In young infants, the whoop may be absent and coughing spasms may be followed by periods of apnoea/ cyanosis

Question 4

Incubation period and disease course of whooping cough

Answer 4

• The incubation period of whooping cough is approximately 7–10 days (range 5–21 days)
• A protracted cough following pertussis infection may last for 3 months or more-> 100 day cough

Question 5

How is whooping cough transmitted

Answer 5

• Whooping cough is spread by aerosol droplets released during coughing- considered to be infectious from onset of symptoms until 48 hours after appropriate Abx treatment
• A previously infected patient may become re-infected with pertussis, though this is likely to be less severe

Question 6

Incidence of whooping cough

Answer 6

Much lower since introduction of the pertussis vaccine in the 1950s- around 6.4 laboratory-confirmed cases per 100,000 population per year in the UK (but probably underdiagnosed.) Whooping cough disproportionately affects infants and young children

Question 7

Complications of whooping cough

Answer 7

• Serious complications include: Apnoea, pneumonia (usually caused by secondary bacterial infection), seizures, encephalopathy
• Less serious complications: Otitis media (secondary bacterial infection), unilateral hearing loss
• Increased intra-thoracic/intra-abdominal pressure due to violent and prolonged coughing-> Pneumothorax, hernia, rib fracture
• Significant mortality, particularly in infants who have not yet completed their primary vaccinations at 4 months

Question 8

Three stages of disease progression in whooping cough

Answer 8

1. Catarrhal phase- Lasts 1-2 weeks. Pertussis is rarely diagnosed during this stage unless there has been known contact with an infected individual
   * Coryza, nasal discharge, sore throat, malaise, low-grade fever, dry, unproductive cough
2. Paroxysmal phase- Typically occurs around 1 week after the catarrhal phase and lasts for 1-6 weeks. Between coughing the child is usually relatively well, with undisturbed sleep
   * Cough gradually becomes more severe (develop ‘whoop’), Bursts of coughing increase in frequency, then remain constant and then gradually decrease in frequency, cough may yield thick mucous plugs or watery symptoms. Most diagnoses made at this stage
3. Convalescent phase- Lasts up to 3 months, during which there is gradual improvement in cough frequency and severity, however, paroxysms may recur

Question 9

Presentation of whooping cough

Answer 9

• Catarrhal phase- coryza and malaise
• A characteristic paroxysmal or spasmodic cough followed by a characteristic inspiratory whoop
• Often worse at night and may culminate in vomiting (tussive vomiting)
• During a paroxysm, the child may go red or blue in the face, with mucous flowing from the nose and mouth
• Epistaxis and subconjunctival haemorrhage can occur due to vigorous coughing

Question 10

Investigations for whooping cough

Answer 10

Clinical diagnosis
Confirmation can be achieved by:
* Nasopharyngeal aspirate/ swab- isolating Bordetella Pertussis
* Real-time PCR
* Anti-pertussis toxin IgG detected in serum
* FBC will show marked lymphocytosis

Question 11

When should a child be admitted to hospital with whooping cough

Answer 11

• Is 6 months of age or younger and acutely unwell.
• Has significant breathing difficulties (for example apnoea episodes, severe paroxysms, or cyanosis).
• Has a significant complication (for example seizures or pneumonia).

Question 12

Management of whooping cough

Answer 12

• Immediately notify the Health protection Unit (HPU)
• Prescribe an antibiotic if the onset of cough is within the previous 21 days
• Clarithromycin for infants less then 1 month
• Azithromycin or clarithromycin for children aged 1 month or older
• Although macrolide antibiotics eradicate the organism, they decrease symptoms only if started during the catarrhal phase
• Advise rest, adequate fluid intake and use of ibuprofen or paracetamol for symptomatic relief
• Advise that there will be a protracted cough that will take several weeks to resolve, even after Abx treatment and to seek medical advice if there are any complications
• children and healthcare workers who have suspected or confirmed whooping cough should stay off nursery, school, or work until 48 hours of appropriate antibiotic treatment has been completed
• Complete outstanding vaccines
• Offer antibiotic prophylaxis to close contacts of the ‘index case’ with suspected or confirmed pertussis