Snapshot A 2-month-old girl infant presents to the emergency room with a 3-day history of a cough and post-tussive emesis. Her mother reports that while she had the Tdap vaccine during pregnancy, the father did not. For the past 2 weeks, the father has had a persistent dry cough. The infant's temperature is 100.4°F (38°C), pulse is 160/min, and respirations are 60/min. Physical exam reveals an infant with a dry cough on expiration and a whooping sound on inspiration. Fine crackles are heard bilaterally on auscultation. She is admitted and given antibiotics. Introduction Classification Bordetella pertussis a gram-negative aerobic coccobacilli transmission respiratory droplets Epidemiology demographics infants are especially at risk < 6 months of age too young to be vaccinated unvaccinated children risk factors exposure to infected people incomplete vaccination HIV exposure Pathogenesis bacteria colonizes mucosal surface pertussis toxin binds to and activates adenylate cyclase by inhibiting Gi impairs phagocytosis, allowing the bacteria to survive tracheal cytotoxin peptidoglycan fragment that impairs cilia, preventing normal clearance of respiratory secretions low lung volume at the beginning of inspiration causes strong inspiration and inspiratory “whoop” Associated conditions whooping cough 100-day cough Prevention DTaP vaccine vaccine against diphtheria, tetanus, and pertussis acellular pertussis vaccine 5 doses before school-age, completed by 4-6 years of age Tdap vaccine booster vaccine at 11-12 years of age should also be given to pregnant mothers and those around them Prognosis can be fatal in infants Presentation Symptoms catarrhal stage (first) low-grade fevers coryza paroxysmal stage (second) dry cough and whoop post-tussive vomiting convalescent stage (third) recovery Physical exam whooping cough in children dry cough on expiration “whoop” on inspiration 100-day cough in adults post-tussive vomiting paroxysmal cough Studies Labs culture in Bordet-Gengou agar Regan Lowe medium polymerase chain reaction serology requires nasopharyngeal secretions on a special swab, as the bacteria will not grow on cotton Making the diagnosis based on clinical presentation and laboratory studies Differential Mycoplasma pneumonia distinguishing factor also presents with a dry cough, but no whooping cough and no posttussive vomiting Complications Pneumonia Failure to thrive Death especially in young infants Apnea especially in young infants