What Is Tetanus (Lockjaw)?

Picture of Clostridium tetani, with spore formation (oval forms at end of rods). Source: CDC/Dr. Holdeman

• Tetanus is frequently fatal infectious disease.
• Tetanus is caused by a type of bacteria (Clostridium tetani).
• The tetanus bacteria often enter the body through a puncture wound, which can be caused by nails, splinters, insect bites, burns, any skin break, and injection-drug sites.
• All children and adults should be immunized against tetanus by receiving vaccinations.
• A tetanus booster is needed every 10 years after primary immunization or after a puncture or other skin wound that could provide an entry point for the tetanus bacteria to enter the body.

Tetanus is an acute, often-fatal disease of the nervous system that is caused by nerve toxins produced by the bacterium Clostridium tetani. This bacterium is found throughout the world in the soil and animal and human intestines. The bacterium can also lay dormant in its spore form for years before becoming activated and developing into a regularly reproducing bacterium.

Contaminated wounds are sites where tetanus bacteria multiply. Deep wounds or those with dead tissue are particularly prone to tetanus infection.

Puncture wounds, such as those caused by nails, splinters, or insect bites, are favorite locations of entry for the bacteria. The bacteria can also be introduced through burns, any break in the skin, and injection-drug sites. Tetanus can also be a hazard to both the mother and newborn child (using the uterus after delivery and through the umbilical cord stump).

The potent toxin that is produced when the tetanus bacteria multiply is the major cause of harm from tetanus.

The tetanus toxin affects the interaction between the nerve and the muscle that it stimulates, specifically at the neuromuscular junction. The toxin amplifies the chemical signal from the nerve to the muscle, which causes the muscles to tighten up in a continuous ("tetanic" or "tonic") contraction or spasm. This results in either localized or generalized muscle spasms.

Tetanus toxin can affect neonates to cause muscle spasms, inability to nurse, and seizures. This typically occurs within the first two weeks after birth and can be associated with poor sanitation methods in caring for the umbilical cord stump of the neonate.

Of note, because of tetanus vaccination programs, first introduced in the late 1940s, tetanus infection rates have dropped substantially. In fact, according to the World Health Organization, there have only been three cases of neonatal tetanus reported in the U.S. since 2000. In each of these cases, the mothers were incompletely immunized.

Unfortunately, throughout the world, tetanus is still common. In 2014, there were over 2,000 cases of neonatal tetanus and over 9,000 cases of non-neonatal tetanus. In comparison, there were 114,000 overall cases reported in 1980.

The incubation period between exposure to the bacteria in a contaminated wound and the development of the initial symptoms of tetanus ranges from two days to two months, but it's commonly within 14 days of injury.

During a one- to seven-day period, progressive muscle spasms caused by the tetanus toxin in the immediate wound area may progress to involve the entire body in a set of continuous muscle contractions. Restlessness, headache, and irritability are common.

The tetanus neurotoxin causes the muscles to tighten up into a continuous ("tetanic" or "tonic") contraction or spasm. The jaw is "locked" by muscle spasms, giving the name "lockjaw" (also called "trismus"). Muscles throughout the body are affected, including the vital muscles necessary for normal breathing. When the breathing muscles lose their power, breathing becomes difficult or impossible and death can occur without life-support measures (mechanical ventilation). Even with breathing support, infections of the airways within the lungs can lead to death.

Tetanus is not contagious. You cannot "catch" tetanus from another infected individual. That means one person cannot be infected by another individual by coming in contact with secretions or other exposures. The bacterial spores must enter a wound to develop into an infection.

General measures to treat the sources of the bacterial infection with antibiotics and drainage are carried out in the hospital while the patient is monitored for any signs of compromised breathing muscles. Treatment is directed toward stopping toxin production, neutralizing its effects, and controlling muscle spasms. Sedation is often given for muscle spasms, which can lead to life-threatening breathing difficulty.

In more severe cases, breathing assistance with an artificial respirator machine may be needed.

The toxin already circulating in the body is neutralized with antitoxin drugs. The tetanus toxin causes no permanent damage to the nervous system after the patient recovers.

After recovery, patients still require active immunization because having the tetanus disease does not provide natural immunization against a repeat episode.

The diagnosis of tetanus is made clinically, based on a patient's history of exposure such as stepping on a rusty nail in the backyard, and by the symptoms present, such as "lockjaw," difficulty swallowing, fever, and generalized muscle spasms.

Once diagnosed and treated, the prognosis is generally good if the patient receives appropriate care early in the illness. The toxin does no permanent damage, and patients who receive appropriate supportive care generally recover. Sometimes symptoms develop rapidly, and some people live in remote areas where they are not able to receive appropriate care and are at a higher risk of death from tetanus.

Active immunization ("tetanus vaccine") plays an essential role in preventing tetanus. Preventative measures to protect the skin from being penetrated by tetanus bacteria are also important. For instance, precautions should be taken to avoid stepping on nails by wearing shoes. If a penetrating wound should occur, it should be thoroughly cleansed with soap and water and medical attention should be sought. Finally, passive immunization can be administered in selected cases (with specialized immunoglobulin).

All children should be immunized against tetanus by receiving a series of five DTaP vaccinations, which generally are started at 2 months of age and completed at approximately 5 years of age. A booster vaccination is recommended at 11 years of age with Tdap.

Follow-up booster vaccination is recommended every 10 years thereafter. While a 10-year period of protection exists after the basic childhood series is completed, should a potentially contaminated wound occur, an "early" booster may be given in selected cases and the 10-year "clock" resets.

Side effects of tetanus immunization occur in approximately 25% of vaccine recipients. The most frequent side effects are usually quite mild (and familiar) and include soreness, swelling, and/or redness at the site of the injection. More significant reactions are extraordinarily rare. The incidence of this particular reaction increases with decreasing intervals between boosters.

In individuals who exhibit the early symptoms of tetanus or in those whose immunization status is unknown or significantly out of date, the tetanus immunoglobulin (TIG) is given into the muscle surrounding the wound with the remainder of the dose given into the buttocks.