Prolonged bacterial bronchitis (a rare diagnosis, mainly made in specialized care)
The most common causes in a school-age child
Asthma
Infection (postinfectious cough, e.g. sinusitis)
Psychogenic causes
A cough can be provoked by various irritants in the inspired air, such as cigarette smoke, or by cold weather.
Gastro-oesophageal reflux (GOR) is possible at any age.
A cough may also be psychogenic in origin or be provoked by a tic disorder.
Post-nasal drip associated with allergic rhinitis and mucosal irritation from the maxillary sinuses is a common cause of a chronic cough.
Very rare causes of a cough include cystic fibrosis Cystic Fibrosis (CF), abnormal cilia, vagal stimulation of the respiratory tract and phrenic, pleuritic or pericardial irritation.
Diagnostic clues
Bronchial hyperactivity may manifest itself as a nocturnal cough, especially in the small hours, or cough during exercise or in cold weather. If the cough is a symptom of asthma, however, the child in most cases has occasional expiratory breathing difficulties and dyspnoea.
A cough originating from GOR is most noticeable at night time and may be associated with excessive burping or regurgitation.
A foreign body in the respiratory tract will usually cause a sudden burst of coughing, but the child may have a history of coughing for several weeks, even for months. It is only possible to confirm the diagnosis radiologically if the foreign body is radio-opaque. In other cases bronchoscopy is indicated.
A cough might continue for several weeks during the convalescent period of many respiratory tract infections, signifying bronchial irritation. Such infections include: rhinovirus, coronavirus, parainfluenza virus and RS virus infections as well as whooping cough and infections caused by Mycoplasma pneumoniae or Chlamydia pneumoniae. Coughing after a COVID-19 infection is not a more common symptom than in other respiratory infections.
Diagnostic investigations
Complete blood count (information on eosinophilic white blood cell count is important)
Possibly, investigations to establish microbial aetiology, such as the detection of antibodies to pertussis, mycoplasma and Chlamydophila pneumoniae (paired sera samples). Tuberculosis should also be remembered as a cause of cough; as necessary, the blood-based IGRA test, for example, should be used.
If an acute infection is diagnosed, asthma investigations can be postponed.
In preschool children, oscillometry may be used as well as exercise testing.
The diagnosis of asthma in a small child is usually based on clinical assessment, history of recurrent episodes of obstruction symptoms, and consideration of risk factors.
References
McCallum GB, Bailey EJ, Morris PS et al. Clinical pathways for chronic cough in children. Cochrane Database Syst Rev 2014;(9):CD006595. [PubMed]
Chang AB, Oppenheimer JJ, Weinberger M et al. Use of Management Pathways or Algorithms in Children With Chronic Cough: Systematic Reviews. Chest 2016;149(1):106-19. [PubMed]
Kantar A. Update on Pediatric Cough. Lung 2016;194(1):9-14. [PubMed]
Kantar A, Chang AB, Shields MD ym. ERS statement on protracted bacterial bronchitis in children. Eur Respir J 2017;50(2):. [PubMed]
Astma [Asthma]. A Current Care Guideline. Working group appointed by the Finnish Medical Society Duodecim, the Finnish Respiratory Society, the Finnish Paediatric Society, the Finnish Paediatric Allergy Society, and the Finnish Society of Clinical Physiology. Helsinki: the Finnish Medical Society Duodecim, 2022. (In Finnish) http://www.kaypahoito.fi/hoi06030