Description

• Acute respiratory tract infection spread by small respiratory droplets
• Bacteria (fimbriae) attach to respiratory epithelial cells and proliferate, producing toxins:
  • Ciliary dysfunction, accumulation of cellular debris, increased mucous production, lymphocytic, and granulocytic infiltration
• Bronchiolar congestion, obstruction, and necrosis
• Obstruction of the airway due to mucous plug, leading to hypoxia and hypoventilation
• Increased intrathoracic or intracranial pressure
• Secondary bacterial infection may exacerbate respiratory distress/failure
• CNS injury caused by encephalitis, increased intracranial pressure, and/or hypoxia
• Uncomplicated cases last 6–10 wk; half of the cases last <6 wk
• Mortality:
  • Mortality greatest in those <1 yr
  • 1.3% for patients <1 mo
  • 0.3% in children 2–11 mo
  • 90% of deaths are secondary to bacterial pneumonia
• Epidemiology:
  • Incubation period is 6–20 d, usually 7–10 d
  • Spread by respiratory droplets
  • Mostly young children; 24% in children <6 mo
  • Increasing incidence in adolescents
  • Adults are the primary reservoir
  • Peak incidence is late summer/fall
  • Preventable with diphtheria–tetanus–pertussis (Tdap) vaccine
• Highly contagious: Up to 90% of household contacts will become infected after exposure

Etiology

Bordetella pertussis:

• A fastidious, gram-negative, pleomorphic bacillus