Tetanus is caused by the bacterium Clostridium tetani, which is common in the environment and enters people through breaks in the skin. Not being up to date on tetanus vaccination is the biggest risk factor, and no diagnostic test can confirm or rule it out.
Clostridium tetani. Image from CDC's page.
How it causes disease
The infection starts with C. tetani spores, which germinate in anaerobic conditions such as those inside the body. The bacteria make very potent toxins that the bloodstream and lymphatic system carry throughout the body. One of them, tetanospasmin (tetanus toxin), causes the serious effects.
Tetanus toxin acts in the sympathetic nervous system and at several sites in the central nervous system — the brain, the spinal cord and the peripheral motor end plates. By interfering with neurotransmitter release and blocking inhibitory impulses, it leaves muscle contraction unopposed, producing the characteristic contractions and spasms.
Spores usually get in through a wound or other break in the skin. Neonatal tetanus usually follows infection of the umbilical stump.
Forms and incubation
| Form | Incubation |
|---|---|
| Generalized and localized | 3 to 21 days, averaging about 8 |
| Neonatal (a generalized form) | symptoms usually 4 to 14 days after birth, averaging about 7 |
| Cephalic | short, usually 1 to 2 days |
The farther the injury is from the central nervous system, the longer incubation tends to be. A shorter incubation goes with more severe disease and a higher chance of death.
Who is at risk
Most U.S. cases today are in adults who were never vaccinated against tetanus or did not keep up with the 10-year boosters. Other risk factors:
- age 80 or older
- diabetes
- immunosuppression
- intravenous drug use
Natural disasters such as earthquakes, hurricanes, floods and tsunamis do not generally raise the amount of tetanus in the environment, but cases can rise afterward because of injuries and because medical services and supplies may be delayed or missing.
Even with modern intensive care, generalized tetanus kills about 1 in 10 patients, and the risk of death is highest in people 80 and older.
Diagnosis
Tetanus is diagnosed clinically, when no more likely cause is found. There is no laboratory test that diagnoses or excludes it; antibody tests exist but are not reliable for either, and CDC does not perform tetanus serology or other tetanus lab testing. Presentation includes:
- trismus (lockjaw)
- spasms and muscle rigidity
- difficulty swallowing or breathing, from muscle spasms
- other consistent findings, such as a rapid heart rate or extreme sweating
Tetanus is uncommon, but it is a reportable condition in the United States.
Prevention
Prevention rests on three strategies, with CDC guidance on when to use the last two:
- proper wound care
- tetanus vaccine
- tetanus immune globulin (TIG) prophylaxis
Following CDC's immunization schedule keeps patients protected.
Sources
Rewritten from the Centers for Disease Control and Prevention page "Clinical Overview of Tetanus" (public domain), in hubnx's own words.
Licence: CC0 1.0 (public domain) · Adapted from www.cdc.gov
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