Pertussis
Pertussis, also known as whooping cough is a highly contagious, acute respiratory illness that is caused by the gram-negative bacterium Bordetella pertussis.
Epidemiology
The incidence of pertussis in children has dramatically decreased since the introduction of pertussis vaccination. However, the incidence has been steadily rising in developed countries since the 1970s and this is superimposed on epidemic cycles occurring on average every 3 years . The morbidity associated with pertussis is usually more substantial in infants and children.
Clinical presentation
The classic symptoms of pertussis are paroxysmal cough, inspiratory whoop and/or post-tussive emesis. However these symptoms may not occur in infected adolescents or adults whom are immunised.
The incubation period following pertussis exposure ranges from 7 to 10 days but can be 3 weeks or longer . The illness typical lasts between 6 to 12 weeks but can last longer and has three stages: catarrhal, paroxysmal, and convalescent.
- catarrhal: associated with coryzal symptoms over 1 to 2 weeks.
- paroxysmal: onset usually second week of illness characterized by paroxysmal cough, inspiratory whoop and post-tussive emesis. this stage lasts for 2 to 8 weeks and may be longer.
- convalescent: decrease frequency of paroxysmal cough and symptoms less severe, lasts 1 to 2 weeks.
Pathology
Bordetella pertussis infection is transmitted via aerosolized respiratory droplets, which are produced during paroxysms of coughing . Once infected, they cause local tissue damage of the ciliated epithelial cells of the upper respiratory tract leading to the symptoms of cough .
Radiographic features
Plain radiograph
Chest radiography may reveal pulmonary consolidation, peribronchial shadowing, perihilar infiltrates or edema with variable degrees of atelectasis, or lymphadenopathy .
Treatment and prognosis
The primary method of prevention for pertussis is vaccination. When infected, macrolides, such as erythromycin, are the treatment of choice. It has been shown to shorten the duration of symptoms when given during the catarrhal stage and shorten the period of contagiousness .
Complications of pertussis may be related to the infection (e.g. pneumonia, otitis media), severe cough (e.g. subconjunctival hemorrhage), or rarely, from hypoxia (seizure and encephalopathy) . Most healthy adolescents and adults will fully recovery.
Differential diagnosis
- mycoplasma pneumoniae
- tuberculosis
- respiratory viruses
- foreign body aspiration
- asthma
- allergic rhinitis
Siehe auch:
