A nurse in the emergency department is assessing a 4-month-old infant who has suspected pertussis. Which of the following findings should the nurse identify as consistent with this diagnosis? (Select all that apply.)

A. Infants, especially those under 6 months, may present with apnea and cyanosis during coughing paroxysms instead of the classic “whoop,” as their respiratory muscles are immature. This is a common severe manifestation in young infants. B. Inspiratory stridor and a barking cough are characteristic of croup, not pertussis. Croup is usually viral in origin and presents with hoarseness and upper airway obstruction, which differs from pertussis. C. Wheezing with exertional dyspnea is more typical of asthma or bronchiolitis, not pertussis. While pertussis can cause hypoxia, wheezing is not a defining feature. D. The paroxysmal stage of pertussis is characterized by repetitive coughing spells followed by a high-pitched inspiratory “whoop”. This is classic for older infants and children, though it may be absent in young infants. E. In the catarrhal stage, pertussis often begins as a mild, dry cough resembling a common cold, which gradually progresses to severe paroxysms. Nighttime exacerbation is common.