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Tetanus, also known as lockjaw, is a disease caused by a type of bacteria that lives in the soil and the intestines of people and animals. When these bacteria get into the body, the poisons they produce affect the nervous system, causing muscle spasms and, in many cases, death. Tetanus is not contagious and can be prevented with a vaccine.

Tetanus is caused by the bacteria Clostridium tetani. Tetanus bacteria can enter the body through an open wound, such as a puncture or a cut; the disease can also be transmitted via improperly sterilized hypodermic needles and practices such as tattooing. Since the bacteria live in the intestines of animals, animal bites can also cause tetanus.

Once the bacteria enter the body, it generally takes anywhere from three days to three weeks for symptoms to develop. The poison, or toxin, produced by the tetanus bacteria enters the central nervous system, affecting the body's nerve cells and causing muscle spasms. When these spasms occur in the muscles involved in chewing, the condition is commonly known as lockjaw. If the muscles of the throat and chest go into spasms, tetanus can be fatal. It is estimated that 40% of the incidences are fatal. Tetanus can be treated with antibiotics and antitoxin medication.

Tetanus is preventable through immunization. In the United States, infants are vaccinated against the disease at 2 months, 4 months and 6 months. This vaccination is known as the DTP shot; it protects against diphtheria, tetanus, and pertussis (whooping cough). In order to insure immunity, it is necessary to get a booster shot every ten years.

Tetanus can also be prevented through the proper cleaning and disinfection of wounds. If the nature of the wound indicates the possibility of tetanus infection (for example, puncture wounds), treatment may include a booster shot.

In the United States, tetanus often occurs among senior citizens, who may not be up to date on their immunizations. In countries where immunization against tetanus is not routine, however, the disease is common among infants. Generally, babies are infected during childbirth or through the newly cut umbilical cord. In infants, the disease is often fatal. However, due to improving immunization programs, the incidence of tetanus worldwide has been declining in recent decades.

See also Childhood diseases.

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