The role of respiratory tract viruses as pathogens in both children and adults remains unclear. For adults, the frequency of epiglottitis is much lower, approximately 10 cases per million. Epiglottitis may arise from direct invasion by Haemophilus influenzae or other pathogens. The role of viruses as primary pathogens has not been demonstrated. On physical examination, the child appears toxic and apprehensive and frequently assumes an airway-preserving posture, i.e. sitting upright, with the jaw protruding forward, while drooling.
Respiration is deliberate without marked tachypnoea.
Tachycardia out of proportion to the amount of pyrexia is a reflection of the hypoxia. Should stridor be absent, an unwary physician might underestimate the severity and rapidity of progression of the patient's worsening air exchange, which may result in cardiopulmonary arrest if left untreated. The presentation of acute epiglottitis in adults is more variable. Most adults have mild illness with a prolonged prodrome. Some patients may be treated for presumed pharyngitis.