• Commonly referred to as “lockjaw”
  • Rare in developed countries due to widespread vaccination, but still prevalent in developing countries
  • About 30 cases per year in U.S.
  • Incidence is higher in individuals >65 yr of age due to loss of immunity
  • Majority of cases in U.S. occur in the unvaccinated, >10 yr since last booster or IVDUs
  • ∼1,000,000 cases worldwide, >300,000 deaths
  • High mortality rates even with treatment
  • Associated with an acute injury but patients often do not remember incident that caused inoculation
  • Increased rates of infection after natural disasters (earthquakes and tsunamis)
  • Incubation period:
    • Inoculation to the appearance of the first symptoms:
      • 3 d to 3 wk or more
    • Period of onset:
      • <7 d – poor prognosis
      • Very poor prognosis if <48 hr from first symptom to initial reflex spasm


  • Clostridium tetani:
    • Slender, motile, heat-sensitive, anaerobic gram-positive rod with a terminal spherical spore
    • Spore characteristics
      • Resistant to oxygen, moisture, temperature extremes
      • Can survive indefinitely until it germinates
      • Ubiquitous in soil and feces
  • When inoculated into a wound or devitalized tissue or injected IV as a contaminant of street drugs, the spores germinate under anaerobic conditions and produce 2 toxins
  • Toxins:
    • Tetanolysin:
      • Damages tissue
      • Does not cause clinical manifestations of tetanus infection
    • Tetanospasmin:
      • Powerful neurotoxin
      • Disrupts the release of neurotransmitters such as γ-aminobutyric acid (GABA)
      • Responsible for the clinical manifestations
  • Muscle spasms
  • Autonomic instability
  • Uncontrolled motor activity

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