Pertussis

6.4 Pertussis



Nigel W. Crawford, Colin V.E. Powell




Essentials



1 Pertussis infection is most common and severe in infants less than 6 months of age.

2 All children less than 6 months with pertussis should be admitted for a period of observation in order to assess the risk of significant apnoea.

3 Three stages of illness occur – catarrhal, paroxysmal and convalescent.

4 The mainstay of treatment is supportive. Admission allows for apnoea monitoring, oxygen and overcoming feeding difficulties.

5 Respiratory complications are the most common, with pneumonia the major cause of mortality (0.5–1%) in infants <6 months.

6 Treatment is with macrolide antibiotics (e.g. erythromycin for 2-week course), best if given early in the course of the illness.

7 Prevention is by universal immunisation with acellular pertussis vaccine in childhood, plus a booster in adolescence/adulthood.


Introduction


Pertussis or ‘whooping cough’ is a bacterial infection of the respiratory tract caused by the Gram-negative coccobacillus, Bordetella pertussis. The word pertussis itself means ‘intensive cough’ and was first described in 1578, when an epidemic occurred in Paris.1 Pertussis is the preferred term because not all cases have the classical paroxysms of coughing, with an inspiratory ‘whoop’, which occur as a massive respiratory effort forces inhaled air against a narrow glottis.



Pathophysiology


Humans are the only reservoir and the incubation period is approximately 7–10 days. Transmission is primarily by direct contact with droplets via the airborne route. The organism is highly communicable early in the illness, with attack rates of 75–100% from symptomatic individuals to susceptible contacts. Pertussis is associated with a significant morbidity and mortality, particularly in young infants.



Epidemiology


With the advent of universal vaccination programmes in the 1940s the incidence of this disease decreased markedly. Due to concerns regarding immunisation, vaccination levels waned in the late 1970s and there was a resurgence in the number of cases. Worldwide there are approximately 250 000 deaths attributed to pertussis per year. There have been epidemics every 3–4 years in Australia, with epidemiological data showing an estimated incidence of 25 cases per 100 000 per year in 1996.2,3



History


The possibility of pertussis should be considered in a child presenting to the emergency department (ED) who has prominent coughing episodes. The diagnosis of pertussis is usually made on the basis of a suggestive clinical history, confirmed by isolation of the organism.


There are three characteristic stages of the illness and presentation is most commonly in the paroxysmal phase.



Stage 1: Catarrhal (1–2 weeks)


Upper respiratory tract infection symptoms, e.g. rhinorrhoea, conjunctivitis, malaise and low-grade fever.



Stage 2: Paroxysmal (2–6 weeks, can be longer)


Consists of paroxysms of coughing which may be followed by an inspiratory ‘whoop’. Facial suffusion, with prominent eyes and protrusion of neck veins, may be seen during these paroxysms. The paroxysms can cause fatigue, which may impair an infant’s ability to take feeds. Post-tussive vomiting commonly follows the coughing episode, but between times the child may appear quite well. It is important to note that young infants may present with apnoea as the only symptom. This can result in a presentation of sudden collapse (see Chapter 1.2).



Stage 3: Convalescent (1–2 weeks)


The paroxysms of coughing, whooping and vomiting decrease in number and severity. The cough may persist for a number of weeks/months and future episodes of upper respiratory tract infections may restimulate the coughing paroxysms.


Pertussis is most severe in infants younger than 6 months of age, particularly the non-immunised. It is these high-risk infants that particularly need to be identified and admitted for a period of observation to exclude significant apnoea events. In infants, the clinical manifestations can mimic those of bronchiolitis or other infective pneumonitis. In partially immune adults and adolescents, who have waning immunity, the presentation is less typical and can be that of a persistent cough.

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Sep 7, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Pertussis

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