Tetanus is a disease caused by the toxin of the bacterium Clostridium tetani that affects the central nervous system, sometimes resulting in death.
Causes, incidence, and risk factors
Spores of the bacterium Clostridium tetani live in the soil and are found around the world. In the spore form, C. tetani may remain dormant in the soil, and it can remain infectious for more than 40 years.
Tetanus causes approximately five deaths per year in the U.S. Internationally, reports show up to 1 million cases annually, mostly in developing countries. Tetanus infections in newborns accounts for about half of tetanus-related deaths in developing countries.
Infection begins when the spores are introduced into an injury or wound. The spores germinate, releasing active bacteria that multiply and produce a neurotoxin called tetanospasmin. Tetanospasmin selectively blocks inhibitory nerve transmission from the spinal cord to the muscles, allowing the muscles to go into severe spasm. Spasmodic contractions can be so powerful that they tear the muscles or cause compression fractures of the vertebrae.
Tetanus often begins with mild spasms in the jaw muscles (trismus), neck muscles, and facial muscles. Stiffness rapidly develops in the chest, back, abdominal muscles, and sometimes the laryngeal muscles (which then interferes with breathing). Muscular seizures (tetany) cause sudden, powerful, and painful contraction of muscle groups. These episodes can cause fractures and muscle tears.
Without treatment, one out of three affected people die. The mortality rate for newborns with untreated tetanus is even higher: two out of three. With proper treatment, less than 10% of infected patients die.
The incubation period is 5 days to 15 weeks, with 7 days as the average. About 100 cases of tetanus occur every year in the U.S., the vast majority in un-immunized individuals or those whose last immunization was no longer current. In developing countries, tetanus frequently causes death in newborn infants when the umbilical stump becomes infected.
- Spasms and tightening of the jaw muscle (“lockjaw”)
- Stiffness and spasms of various muscle groups o Neck muscles o Chest muscles o Abdominal muscles o Back muscles, often causing arching (opisthotonos)
- Tetanic seizures (painful, powerful bursts of muscle contraction)
Additional symptoms that may be associated with this disease:
- Excessive sweating
- Swallowing difficulty
- Hand or foot spasms
- Uncontrolled urination and/or defecation
Signs and tests
Diagnosis of tetanus is based on the history and physical findings that are characteristic of the disease. Diagnostic studies generally are of little value, as cultures of the wound site are negative for C. tetani two-thirds of the time. When the culture is positive, it confirms the diagnosis of tetanus
Tests that may be performed include the following:
- Culture of the wound site (may be negative even if tetanus is present)
- Tetanus antibody test
Other tests may be used to rule out meningitis, rabies, strychnine poisoning, or other diseases with similar symptoms.
- Control and reverse the tetany with antitoxin (tetanus immune globulin).
- Give penicillin to kill C. tetani (other antibiotics such as clindamycin, erythromycin, or metronidazole can be used in patients who are allergic to penicillin).
- Remove and destroy the source of the toxin through surgical exploration and cleaning of the wound (debridement).
- Treat symptoms. Muscle spasms can be treated with muscle relaxants such as diazepam.
- Bedrest with a nonstimulating environment (dim light, reduced noise, and stable temperature) may be recommended.
- Sedation may be necessary to keep the affected person calm.
Respiratory support with oxygen, endotracheal tube, and mechanical ventilation may be necessary.
The death rate is high in children and in the elderly. Wounds on the head or face seem to be more dangerous than those on the body. If the person survives the acute illness, recovery is generally complete. Uncorrected episodes of hypoxia (lack of oxygen) caused by muscle spasms in the throat may lead to irreversible brain damage.
- Airway obstruction
- Respiratory arrest
- Heart failure
- Brain damage due to lack of oxygen during spasms
Calling your health care provider
Call your health care provider if you sustain an open wound, particularly if you are injured outdoors or if the wound has otherwise been in contact with soil, and you have not received a tetanus booster (vaccine) within five years or you are not sure of your vaccination status.
Call for an appointment with your health care provider if you have never been immunized against tetanus as an adult or child, if your children have not been immunized, or if you are unsure of your tetanus immunization (vaccine) status.
Tetanus is completely preventable by active tetanus immunization. Immunization is thought to provide protection for 10 years. Studies in the army suggest that good protection persists up to 12 years after the last immunization.
In the U.S., immunizations begin in infancy with the DTaP series of shots. The DTaP vaccine is a “3-in-1” vaccine that protects against diphtheria, pertussis, and tetanus. It is a safer version of an older vaccine known as DTP, which is no longer used in the U.S.
Td vaccine is used as a booster to maintain immunization in teenagers and adults.
Older teenagers and adults who have sustained injuries, especially puncture-type wounds, should receive booster immunization for tetanus if more than 10 years have passed since the last booster.
Thorough cleaning of all injuries and wounds and the removal of dead or severely injured tissue (debridement), when appropriate, may reduce the risk of developing tetanus. If you have been injured outside or in any way that makes contact with soil likely, contact your health care provider regarding the possible risk for tetanus.
Many people believe injuries caused by rusty nails are the most dangerous. This is true only if the nail is dirty as well as rusty, as is usually the case. It is the dirt, not the rust, that carries the risk for tetanus.
by Martin A. Harms, M.D.
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.