Tetanus

Basics

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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