Infection: Tetanus

Definition
Description
Demographics
Causes and Symptoms
Diagnosis
Treatment
Prognosis
Prevention
The Future
For more information

Definition

Tetanus is an infectious disease that, by the production of a potent toxin, affects the muscles of the body, causing stiffness, spasms, difficulty breathing, and a risk of death. It is caused by a bacterium called Clostridium tetani, which lives in the soil.

Description

Tetanus has been familiar to doctors for centuries; it was described by Hippocrates around 400 BCE as a common but frequently fatal disease. He was the first medical writer to list the characteristic symptoms of the disease, including the tightening of the jaw muscles that gave tetanus its common name of lockjaw.

Tetanus is caused by an anaerobic bacterium that exists in the soil as a spore and gains entrance to the body through a wound, often a puncture or a crushing wound. There are four basic forms of tetanus: neonatal, which affects newborns; cephalic, which is limited to the head; local, which affects the muscles closest to the infected wound; and generalized, which affects the entire body and can lead to death.

Demographics

Tetanus was a fairly common disease until the twentieth century. The bacterium that causes tetanus was first identified in 1885, and an effective vaccine was developed in the 1940s. This vaccine helped to make tetanus a rare disease in the United States; only twelve cases of tetanus were diagnosed in American soldiers during World War II, compared to thousands of deaths from tetanus among unimmunized German and Italian troops. The annual number of cases of tetanus among civilians in the United States fell from 600 in 1940 to forty-three in 2000. As of the early 2000s, the rate of tetanus in the United States is 0.16 cases per 1 million population.

Most cases of tetanus in the United States are cases of generalized tetanus; neonatal tetanus is very rare in North America. The adults at greatest risk include intravenous drug users, Hispanics, people over sixty

who have allowed their immunization to lapse, and older adults with diabetes.

In the developing world, however, neonatal tetanus is a major killer of newborns, responsible for thousands of deaths. It occurs when the stump of the baby's umbilical cord becomes infected by dirt containing tetanus spores. There are about a million cases of tetanus reported around the world each year, causing between 300,000 and 500,000 deaths. The countries that have the highest rates of tetanus are those with hot, damp climates and soils containing large amounts of animal manure.

Causes and Symptoms

The bacterium that causes tetanus is anaerobic, which means that it only thrives in the absence of oxygen. It is found in the soil, in dust, in the manure produced by farm animals and household pets, and in the digestive tracts of 10–25 percent of humans. The bacterium forms spores (an inactive stage) that can remain dormant outdoors for years. When the spores get into the body through a puncture wound, an injury that crushes tissue, or a drug injection, they germinate (start to grow) in dead or dying tissue, which lacks oxygen. Germination usually occurs between three days and three weeks after the spores are introduced into the body. The bacteria secrete two toxins, one of which affects the nervous system

and causes the muscle stiffening and spasms that are characteristic of tetanus.

The first symptoms of tetanus usually appear about eight days after infection. The patient typically has a sore throat with difficulty swallowing, headache, stiffness in the jaw muscles known as trismus (lockjaw), followed by stiffness of the neck, heavy sweating, fever, stiffness in the muscles of the abdomen, and spasms in the muscles close to the site of the cut or other injury.

The Bridge Builder

John Augustus Roebling (1806–1869) was one of the greatest civil engineers of the nineteenth century, famous for the beauty as well as the strength of the bridges he designed. Roebling left his native Germany in 1831 to seek new opportunities in the United States. Settling near Pittsburgh, Pennsylvania, he began to work for the state as a designer of railroad bridges. He built several suspension bridges over the Allegheny and Monongahela Rivers, using wire ropes and cables that he invented himself.

New bridges were a vital part of efficient troop movement during the Civil War, and Roebling began work on a bridge across the Ohio River at Cincinnati, Ohio, in 1863. It was the longest suspension bridge in the world when completed in 1867. A few months later, Roebling began work on his last project—the Brooklyn Bridge across the East River in New York. The bridge, a world-famous landmark, cost Roebling his life in 1869. He believed in supervising the construction work himself rather than giving the job to others, and as he stood at the edge of a dock near the construction site a ferry crushed his foot against the dock. Roebling allowed doctors to amputate his crushed toes but refused further medical treatment.

Twenty-four days later he was dead of tetanus, a disease for which the cause would not be identified for another sixteen years and an effective treatment would not be available for another half century.

In severe tetanus, the patient has spasms of the arms, legs, and back muscles that can be violent enough to dislocate or break bones. The spasms can also affect the vocal cords and the muscles that control

breathing. The patient's blood pressure may alternate between being too high and too low, and the heart rhythm may change from a fast heartbeat to an overly slow heartbeat. Without treatment, the patient may die from respiratory failure or the heart suddenly stopping.

Diagnosis

The diagnosis of tetanus is usually based on the patient's history, particularly a recent crushing or penetrating injury, and such symptoms as fever, muscle stiffness, and changes in blood pressure and heart rhythm. The doctor will also check the patient's record of immunization against tetanus.

There are no laboratory tests or imaging studies that are helpful in diagnosing the disease, although the doctor may order a blood test to rule out certain types of poisons.

Treatment

Treatment can begin at home with cleaning a wound carefully with soap and running water. A clean cloth can be applied to stop the bleeding. If the wound was caused by a farm tool or other object left outdoors, or resulted from a crushing injury, the injured person should consult their doctor, particularly if they have not had a tetanus booster shot within the past ten years.

Medical treatment begins with prevention, using debridement (surgical removal of any dead or dying tissue that may contain tetanus bacteria). The next step in treatment consists of administering human tetanus immune globulin (TIG), a form of immunization that neutralizes the toxin already produced by the bacteria. TIG produces temporary protection against tetanus in patients who have not been vaccinated against the disease or who have not had a booster shot in the last ten years.

Other drugs that are given to treat severe tetanus include various antibiotics to kill the bacteria directly, muscle relaxants and tranquilizers to prevent muscle spasms, sedatives to help the patient sleep, and painkillers to relieve the pain caused by the muscle spasms.

Patients who are having trouble breathing may be placed on a ventilator and given fluids intravenously to prevent dehydration and provide extra nutrition. The extra calories are needed because the muscle spasms of severe tetanus use up large amounts of the body's energy stores.

Prognosis

The prognosis of tetanus depends partly on the form of the disease. Cephalic and local tetanus have very high recovery rates. Neonatal tetanus, however, has a mortality rate of close to 90 percent. Generalized tetanus causes about five deaths per year in the United States; the overall mortality rate is about 30 percent but is close to 50 percent in people over the age of sixty. If the patient recovers, however, he or she usually recovers completely, without lasting damage to the nervous system.

Prevention

Prevention is the most effective defense against tetanus. Children are usually immunized against tetanus by a combination vaccine that also protects against diphtheria and whooping cough. They are usually given five doses of the combination vaccine, at two, four, six, and fifteen months of age, and a final dose at four to six years. They should then have a booster shot every ten years.

Adults who have not had a booster shot within the last ten years should be given a booster shot as well as TIG if they see their doctor about a wound that might be infected by tetanus spores.

The Future

Tetanus is unlikely to ever be completely eradicated because the spores that cause the disease are so widely distributed in soils around the world and in the digestive systems of humans and animals. The best hope for lowering the worldwide death toll from this disease is universal immunization and greater availability of appropriate treatments.

WORDS TO KNOW

Anaerobic: Capable of living in the absence of oxygen.

Debridement: Surgical removal of dead or dying tissue.

Spore: The dormant stage of a bacterium.

Trismus: The medical name for the spasms of the jaw muscles caused by tetanus.

SEE ALSO Whooping cough

For more information

BOOKS

Guilfoile, Patrick. Tetanus. New York: Chelsea House Publishers, 2008.

PERIODICALS

Centers for Disease Control and Prevention (CDC). “Tetanus Surveillance— United States, 1998–2000.” Morbidity and Mortality Weekly Report 52 (June 20, 2003). Available online at http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5203a1.htm (accessed April 21, 2008). Includes maps and graphs at the bottom of the page that give the number of cases per state and rates of survival.

WEB SITES

Centers for Disease Control and Prevention (CDC). Tetanus Disease In-Short (Lockjaw). Available online at http://www.cdc.gov/vaccines/vpd-vac/tetanus/in-short-both.htm (updated July 2007; accessed April 21, 2008).

Mayo Clinic. Tetanus. Available online at http://www.mayoclinic.com/health/tetanus/DS00227/DSECTION=1 (updated September 21, 2006; accessed April 21, 2008).

National Network for Immunization Information Fact Sheet. Important Facts for Parents to Know about the DTaP Vaccine. Available online in PDF format at http://www.immunizationinfo.org/assets/files/pdfs/2_DTAP_facts.pdf (updated October 2000; accessed April 21, 2008).

TeensHealth. Tetanus. Available online at http://www.kidshealth.org/teen/infections/bacterial_viral/tetanus.html (updated April 2007; accessed April 21, 2008).