If Clostridium tetani spores are deposited in a wound, the neurotoxin interferes with nerves that control muscle movement.
The infection can cause severe muscle spasms, serious breathing difficulties, and can ultimately be fatal. Although tetanus treatment exists, it is not uniformly effective. The best way to protect against tetanus is to take the vaccine.
Here are some key points about tetanus. More detail and supporting information is in the main article.
What is tetanus?
Tetanus is a serious bacterial infection. The bacteria exist in soil, manure, and other environmental agents. A person who experiences a puncture wound with a contaminated object can develop the infection, which can affect the whole body. It can be fatal.
In the United States (U.S.), there are about 30 cases a year. These are mostly people who have not been vaccinated against tetanus or who have not kept up their booster shots every 10 years.
Causes of tetanus
Tetanus is caused by the Clostridium tetani bacterium. Clostridium tetani spores are able to survive for a long time outside of the body. They are most commonly found in animal manure and contaminated soil, but may exist virtually anywhere.
When Clostridium tetani enter the body, they multiply rapidly and release tetanospasmin, a neurotoxin. When tetanospasmin enters the bloodstream, it rapidly spreads around the body, causing tetanus symptoms.
Tetanospasmin interferes with the signals traveling from the brain to the nerves in the spinal cord, and then on to the muscles, causing muscle spasms and stiffness.
Puncture wounds - Clostridium tetani enters the body mainly through skin lesions (skin cut or puncture wound). Thoroughly cleaning any cut helps prevent an infection from developing.
Common ways of contracting tetanus
- Wounds that have been contaminated with saliva or feces
- Crush injuries
- Wounds that include necrotic (dead) tissue
- Puncture wounds
Rare ways of contracting tetanus
- Surgical procedures
- Superficial wounds
- Insect bites
- Compound fractures
- Intravenous drug use
- Injections into the muscle (intramuscular)
- Dental infections
Symptoms of tetanus
Tetanus symptoms usually emerge about 7-10 days after initial infection; however, this can vary from 4 days to about 3 weeks, and, in some cases, it may take months.
In general, the further the injury site is from the central nervous system, the longer the incubation period. Patients with shorter incubation times tend to have more severe symptoms.
Muscle symptoms - spasms and muscular rigidity (muscles become stiff). Stiffness usually starts with the chewing muscles, hence the name lockjaw.
Muscle spasms then spread to the neck and throat, causing dysphagia (difficulty swallowing). Patients often go on to have spasms in their facial muscles.
Breathing difficulties may result from neck and chest muscle stiffness. With some patients, abdominal and limb muscles are also affected.
In severe cases, the spine will arch backward as the back muscles are affected - this is more common when children are infected.
Most patients with tetanus will also have the following symptoms:
- Bloody stools (feces)
- Sensitivity to touch
- Sore throat
- Tachycardia (rapid heartbeat)
- Fractures - sometimes, in severe cases, the muscle spasms and convulsions may lead to bone fractures.
- Aspiration pneumonia - if secretions or contents of the stomach are inhaled, a lower respiratory tract infection can develop, leading to pneumonia.
- Laryngospasm - the larynx (voice box) goes into a spasm which can last up to a minute and cause breathing difficulties. In severe cases, the patient can suffocate.
- Tetanic seizures - if infection spreads to the brain, the patient can have epileptic-like fits (seizures).
- Pulmonary embolism - a blood vessel in the lung can become blocked and affect breathing and circulation. The patient will urgently need oxygen therapy and anti-clotting medication.
- Severe kidney failure (acute renal failure) - severe muscle spasms can result in the destruction of skeletal muscle which can cause myoglobin - a muscle protein - to leak into the urine. This can cause acute renal failure (severe kidney failure).
Prevention of tetanus
Most cases of tetanus occur in people who have never been immunized (never had the vaccine), or who did not have a booster shot within the preceding decade.
The tetanus vaccine
The tetanus vaccine is routinely given to children as part of the DTaP (diphtheria and tetanus toxoids and acellular pertussis) shot. The DTaP vaccine consists of five shots, usually given in the arm or thigh of children when they are aged:
- 2 months
- 4 months
- 6 months
- 15 - 18 months
- 4 - 6 years
A booster is normally given between the ages of 11 and 18 years, and then another booster every 10 years. If an individual is traveling to an area where tetanus is common, they should check with a doctor regarding vaccinations.
Do I need a tetanus shot?
Anyone who receives a deep or dirty wound and has not had a booster shot over the last 5 years should have another booster.
A patient in this situation may also be given tetanus immune globulin, which works to prevent infection. It is important that medical attention is sought swiftly as tetanus immune globulin only works for a short time after the injury.
In many countries, the average doctor may never see a patient with tetanus. This is because the tetanus vaccine is part of childhood immunization and the infection has become rare. In the United States in 2009, for example, there were only 19 reported cases of tetanus.
The earlier a patient is diagnosed with tetanus, the more effective the treatment will be. A patient with muscle spasms and stiffness who has recently had a wound or cut is usually diagnosed quickly.
Diagnosis may take longer with patients who inject drugs because they often have other medical conditions. They made need a blood test for confirmation.
Anybody who experiences muscle spasms and stiffness should seek medical attention immediately.
Treatments for tetanus
Wounds should be thoroughly cleaned to prevent infection.
Any cut or wound must be thoroughly cleaned to prevent infection. A tetanus-prone wound should be treated by a medical professional immediately.
What is a tetanus-prone wound? According to the National Health Service (NHS), United Kingdom, it is defined as:
- A wound or burn that requires surgical intervention that is delayed for over 6 hours
- A wound or burn that has a considerable amount of removed (devitalized) tissue
- Any puncture-type injury that has been in contact with manure or soil
- Serious fractures where the bone is exposed to infection (compound fractures)
- Wounds or burns in patients with systemic sepsis
Any patient with a wound listed above should receive TIG (tetanus immunoglobulin) as soon as possible, even if they have been vaccinated. Tetanus immunoglobulin contains antibodies that kill Clostridium tetani. It is injected into a vein and provides immediate short-term protection against tetanus.
TIG is just short-term and does not replace the long-term effects of vaccination. Experts say that TIG injections can be safely administered to pregnant and breastfeeding mothers.
Antibiotics - doctors may prescribe penicillin or metronidazole for tetanus treatment. These antibiotics prevent the bacterium from multiplying and producing the neurotoxin that causes muscle spasms and stiffness. Patients who are allergic to penicillin or metronidazole may be given tetracycline instead.
In treating muscle spasms and stiffness, patients may be prescribed:
- Anticonvulsants - such as diazepam (Valium) - relaxes the muscles to prevent spasms, reduces anxiety, and works as a sedative.
- Muscle relaxants - such as baclofen - suppresses nerve signals from the brain to the spinal cord, resulting in less muscle tension.
- Neuromuscular blocking agents - these medications block the signals from nerves to muscle fibers and are useful in controlling muscle spasms. They include pancuronium and vecuronium.
If the doctor thinks the tetanus prone wound is very large, they may surgically remove as much of the damaged and infected muscle as possible (debridement).
Debridement is the act of removing dead or contaminated tissue, or foreign material. In the case of a tetanus-prone wound, the foreign material may be dirt or manure.
A patient with tetanus requires a high daily calorie intake because of increased muscle activity.
Some patients may need ventilator support to help with breathing if their vocal cords or respiratory muscles are affected.