Correctly termed pertussis, this is a respiratory-tract infection caused by the bacterium Bordetella pertussis and spread by droplets. It may occur at all ages, but around 90 per cent of cases are in children aged under five. Most common during the winter months, it tends to occur in epidemics (see EPIDEMIC), with periods of increased prevalence occurring every three to four years. It is a notifiable disease (see NOTIFIABLE DISEASES). The routine immunisation of infants has drastically reduced the incidence of this potentially dangerous infection. In an epidemic of whooping-cough, which extended from the last quarter of 1977 to mid-1979, 102,500 cases of whooping-cough were notified in the United Kingdom, with 36 deaths. This was the biggest outbreak since 1957 and its size was partly attributed to the fall in vaccination acceptance rates because of media reports suggesting that pertussis vaccination was potentially dangerous and ineffective. Currently, over 90% of UK children receive pertussis vaccine in infancy and about 1,000 cases are proved bacteriologically annually (although there must be many more unproven cases).
The first, or catarrhal, stage is characterised by mild signs and symptoms, with sneezing, conjunctivitis (see under EYE, DISORDERS OF), sore throat, mild fever and cough. Lasting 10–14 days, this stage is the most infectious; unfortunately it is almost impossible to make a definite clinical diagnosis, although analysis of a nasal swab may confirm a suspected case. This is followed by the second, or paroxysmal, stage with irregular bouts of coughing, often prolonged, and typically more severe at night. Each paroxysm consists of a succession of short sharp coughs, increasing in speed and duration, and ending in a deep, crowing inspiration, often with a characteristic ‘whoop’. Vomiting is common after the last paroxysm of a series. Lasting 2–4 weeks, this stage carries the greatest risk of complications. These may include PNEUMONIA and partial collapse of the lungs, and fits may be induced by cerebral ANOXIA. Less severe complications caused by the stress of coughing include minor bleeding around the eyes, ulceration under the tongue, HERNIA and PROLAPSE of the rectum. Mortality is greatest in the first year of life, particularly among neonates – infants up to four weeks old. Nearly all patients with whooping-cough recover after a few weeks, with a lasting IMMUNITY. Very severe cases may leave structural changes in the lungs, such as EMPHYSEMA, with a permanent shortness of breath or liability to ASTHMA. Symptoms may last for up to 3 months and may recur for a time when the child next has a cold. Adults with whooping cough tend not to ‘whoop’ but rather to have a persistent, dry, debilitating cough for a prolonged period.
Antibiotics, such as ERYTHROMYCIN or TETRACYCLINES are sometimes prescribed during the catarrhal stage. There is no evidence that they change the progress of the illness but their use reduces the risk of spread to brothers and sisters. Cough suppressants are not always helpful unless given in high (and therefore potentially narcotic) doses, and skilled nursing may be required to maintain nutrition, particularly if the disease is prolonged, with frequent vomiting. Very young infants may require hospital admission for observation in case they need to be artificially ventilated for a time.