Whooping Cough (aka Pertussis)
This is a type of bronchiolitis, caused by the bacterium Bordetella Pertussis. It is highly infectious, and can be deadly. It causes roughly around 300 000 deaths worldwide each year, although in the UK deaths are rare. Other LRTI’s are more dealy
Epidemiology and Aetiology
- Endemic in the worldwide population
- Epidemics every 2-3 years
- Relatively low incidence in the UK, due to vaccination program
- Peak age of incidence – 3 years
- Only 1% of cases in the UK require hospitalisation
- Generally, more severe in the very young
The infection generally lasts about 6weeks:
Catarrhal phase – 1-2 weeks - symptoms of coryza. Most contagious during this phase.
Paroxysmal phase – 3-6 weeks – there is a characteristic cough.
- Present day and night, but often worse during the night
- Spasmodic – usually child will spasm of cough, following by an inspiratory whoop as the child tries to catch their breath at the end of the spasm. It is this inspiratory whoop after which the condition is named. In children it is ‘high-pitched’ but in adults, usually not.
- Spasm may induce vomiting
- During the cough spasms, the child may go red or blue in the face. Mucus may be expelled from the nose and mouth
- Epistaxis (nose bleed) and subconjunctival haemorrhage may occur during spasms.
- There is usually no fever or wheeze
Convalescent phase – days to months
- Symptoms gradually decrease, but may still be present after several months in some cases
Generally rare but can be life-threatening. These can include pneumonia, convulsions and bronchiectasis.
Younger children may not have a cough, but mat instead suffer from apnoea.
Although adults can still quite easily contract the disease, it is less dangerous in adults.
- Nasal swab – to identify the organism. Usually only effective within the first 3 weeks of the infection, and even then, an unreliable test.
- FBC – there is often a lymphocytosis (>15 x109/L)
- Antibody test – test for antibodies against pertussis toxin or Bordetella pertussis related products.
- Any child having coughing spasms should be admitted to hospital
- Erythromycin is the treatment of choice. If treatment begins in the catarrhal phase then symptoms will resolve relatively quickly, and infectivity is also reduced. However, this is rare, as during this phase diagnosis of whooping cough is extremely difficult. If treatment starts in the paroxysmal phase, then although the causatory organism is still eradicated, symptoms will usually persist.
- Prophylactic antibiotics (erythromycin) are offered to anybody who has close contact with the patient (e.g. parents, siblings, school children/staff).
This does not provide Immunity! However, it reduces the risk of contracting the condition, as well as the severity of the infection if you are unlucky enough to get it. The level of protection declines as childhood progresses.
Why is the rate of infection so low, if protection reduces with age? – Herd Immunity! – young children are the most likely to pass on respiratory infections. As they are immunised, then the disease finds it difficult to establish itself in the population.
Vaccination Schedule – pertussis requires 4 vaccinations:
- Age 2 months
- Age 3 months
- Age 4 months
- Age 3 years and 4 months