Patients may complain of a persistent cough following symptoms of an upper respiratory tract infection; when the cough lasts for > 3 weeks, it is no longer considered to be an acute cough. Instead, it is considered to be in the category of subacute cough. Some authors have labeled the cough following a viral or virus-like infection (eg, with Mycoplasma or Chlamydophila) as a postinfectious cough. In the definition of postinfectious cough are the following elements: the cough lasts no > 8 weeks; the chest radiograph findings are negative, ruling out pneumonia; and the cough eventually resolves, usually on its own. Hence, the subacute postinfectious cough is distinguished from the chronic cough by the duration of coughing, with the chronic cough lasting for at least 8 weeks and in most instances for many months and even years. 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.” antimicrobialmed.com
While the pathogenesis of the postinfectious cough is not known, it has been thought to be due to the extensive disruption of epithelial integrity and widespread airway inflammation of the upper and/or lower airways with or without transient airway hy-perresponsiveness. Bronchoscopy and biopsy performed on patients with uncomplicated influenza A infection, for example, reveals extensive desquamation of epithelial cells to the level of the basement membrane. The percentage of lymphocytes and neutrophils in BAL fluid is high, and bronchial biopsy material shows a lymphocytic bronchitis. Although bronchial hyperresponsiveness is present in some patients with postinfectious cough, eosinophilic inflammation, which is typical of asthma, is absent. Despite the presence of symptomatic heightened coughing, cough receptor sensitivity to capsaicin and tartaric acid inhalation challenge has not been found to be heightened in the acute and convalescent phases of postinfectious cough due to Mycoplasma pneumoniae.
Category: Respiratory Symptoms
Tags: Bordetella pertussis, pertussis infection, postinfectious cough, postviral cough