Pertussis

Basics

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

Etiology

Bordetella pertussis:
  • A fastidious, gram-negative, pleomorphic bacillus

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