Background: Patients who complain of a persistent cough lasting >3 weeks after experiencing the acute symptoms of an upper respiratory tract infection may have a postinfectious cough. Such patients are considered to have a subacute cough because the condition lasts for no >8 weeks. The chest radiograph findings are normal, thus ruling out pneumonia, and the cough eventually resolves, usually on its own. The purpose of this review is to present the evidence for the diagnosis and treatment of postinfectious cough, including the most virulent form caused by Bordetella pertussis infection, and make recommendations that will be useful for clinical practice.
Methods: Recommendations for this section of the guideline were obtained from data using a National Library of Medicine (PubMed) search dating back to 1950, which was performed in August 2004, of the literature published in the English language. The search was limited to human studies, using the search terms "cough," "postinfectious cough," "postviral cough," "Bordetella pertussis," "pertussis infection," and "whooping cough."
Results: The pathogenesis of the postinfectious cough is not known, but it is thought to be due to the extensive inflammation and disruption of upper and/or lower airway epithelial integrity. When postinfectious cough emanates from the lower airway, this is often associated with the accumulation of an excessive amount of mucus hypersecretion and/or transient airway and cough receptor hyperresponsiveness; all may contribute to the subacute cough. In these patients, the optimal treatment is not known. Except for bacterial sinusitis or early on in a B pertussis infection, therapy with antibiotics has no role, as the cause is not bacterial infection. The use of inhaled ipratropium may be helpful. Other causes of postinfectious cough are persistent inflammation of the nose and paranasal sinuses, which leads to an upper airway cough syndrome (previously referred to as postnasal drip syndrome), and gastroesophageal reflux disease, which may be a complication of the vigorous coughing. One type of postinfectious cough that is particularly virulent is that caused by B pertussis infection. When the cough is accompanied by paroxysms of coughing, posttussive vomiting, and/or an inspiratory whooping sound, the diagnosis of a B pertussis infection should be made unless another diagnosis is proven. This infection is highly contagious but responds to antibiotic coverage with an oral macrolide when administered early in the course of the disease. A safe and effective vaccine to prevent B pertussis is now available for adults as well as children. It is recommended according to CDC guidelines.
Conclusions: In patients who have a cough lasting from 3 to 8 weeks with normal chest radiograph findings, consider the diagnosis of postinfectious cough. In most patients, a specific etiologic agent will not be identified, and empiric therapy may be helpful. A high degree of suspicion for cough due to B pertussis infection will lead to earlier diagnosis, patient isolation, and antibiotic treatment.