Causes and How It Spreads

Tetanus is an infection caused by a bacterium called Clostridium tetani. Spores of tetanus bacteria are everywhere in the environment, including soil, dust, and manure. The spores develop into bacteria when they enter the body. Unlike other vaccine-preventable diseases, tetanus is not spread from person to person.

Common ways tetanus gets into your body

Woman massaging her foot

Stepping on nails or other sharp objects is one way people are exposed to the bacteria that cause tetanus. These bacteria are in the environment and get into the body through breaks in the skin.

The spores can get into someone’s body through broken skin, usually through injuries. Tetanus bacteria are more likely to infect certain breaks in the skin. These include:

  • Wounds contaminated with dirt, feces (poop), or saliva (spit)
  • Puncture wounds (wounds caused by an object, like a nail or needle, breaking the skin)
  • Burns
  • Crush injuries (injury to a body part due to pressure from another object or being squeezed between two heavy objects)
  • Injuries with dead tissue

Other ways tetanus gets into your body

Tetanus bacteria can also infect someone’s body through breaks in the skin caused by:

  • Clean superficial wounds (when only the topmost layer of skin is scraped off)
  • Surgical procedures
  • Insect bites
  • Dental infections
  • Compound fractures (an exposed broken bone)
  • Chronic sores and infections
  • Intravenous (IV) drug use
  • Intramuscular injections (shots given in a muscle)

Time from exposure to illness

The incubation period — time from exposure to illness — is usually between 3 and 21 days (average 8 days). However, it may range from 1 day to several months, depending on the kind of wound. Most cases occur within 14 days. In general, doctors see shorter incubation periods with:

  • More heavily contaminated wounds
  • More serious disease