Tetanus

Tetanus is a condition caused by a nerve toxin that is produced by the bacterium Clostridium tetani, a cousin of the bacteria that cause gangrene and botulism.  Although it was a serious worldwide public health problem in the past, tetanus cases have decreased dramatically since the introduction of a vaccine.

The cases of tetanus that do occur are often seen in those who either have not been vaccinated or have failed to keep their immunizations up to date, as protection from the vaccine declines over time.

Canada now averages about 3 reported cases each year. Only 6 people have died of tetanus in this country since 2000.

Clostridia are anaerobic bacteria, meaning they thrive best in the absence of oxygen. They're commonly found in soil, but can also be found in the lower intestines of mammals. They can produce spores that can cause infection years later.

Anyone who cuts himself or herself with a dirty object is at risk of getting Clostridium tetani in the wound. The bacteria are only really dangerous if they're in wound tissue that's cut off from a good oxygen supply. "Crush" wounds and deep puncture wounds are good candidates for such infections, as are burns, surgical wounds, and punctures with dirty needles. Most cases of tetanus in North America are found in older people following surgery, in people with diabetes, and in intravenous drug users who reuse unclean syringes. However, infection may develop from even minor wounds.

The incidence of tetanus in newborns is very rare in North America. In developing countries many infants are affected by neonatal tetanus.  Infections in newborns usually result from unclean birth practices either during or after delivery. As the bacteria grow and multiply, they produce a nerve toxin. As with botulism, it's the toxin that does the damage, not the organisms themselves. The toxin binds to nerve endings that normally serve to calm the muscles. In the absence of receiving such calming signals, the muscles contract and become rigid and very sensitive to external input, leading to spasms. The spasms generally occur throughout the body, but sometimes they are localized to the muscles near the entry wound.

Symptoms may appear anywhere from 3 days to 21 days after the wound has been infected, but the typical incubation period (time between infection and symptoms) is about 8 days. Symptoms can be mild or severe and include:

• sweating and chills
• difficulty swallowing
• headache
• irritability
• jaw and neck stiffness
• fever
• restlessness
• sore throat
• stiff arms and legs
• rapid heartbeat

Symptoms soon progress to classic tetanus:

• difficulty opening the jaw - that's why tetanus is sometimes called "lockjaw"
• muscle spasms in the back, neck, or abdomen

People with tetanus often develop a fixed expression with a tight, stretched smile and arched eyebrows. They often go into painful whole-body spasms when slightly disturbed, for example by fluffing their pillow. They may sweat a great deal during these spasms. They may be unable to speak because of spasms in the chest or throat – these can also make breathing difficult. Rigidity in the bladder and bowels can cause retention of urine and constipation. Blue lips or nail beds are a sign of depressed breathing, meaning there’s too little oxygen or too much carbon dioxide in the blood.

People with tetanus are usually mentally alert. The pulse can be fast, but fever is rarely very high. Sometimes the face is unaffected and the spasms are confined to muscles near the wound. In this case, there is a better chance of a full recovery.

Complications of tetanus can include pneumonia, broken bones, skin sores, muscle tears, low blood pressure and death (most commonly from respiratory failure).

The bacteria can't always be detected in the wound, but the particular combination of symptoms and a recent wound usually paints a clear picture of tetanus.

Meningitis and encephalitis (brain infections) can cause similar spasms and rigidity, but they usually interfere with senses such as hearing, while tetanus doesn't. Taking a sample of cerebrospinal fluid (CSF) allows the doctor to rule out both of these diseases.

People with tetanus need to be in an intensive care unit so they can receive treatment and continuous monitoring.

Treatment of tetanus usually includes:

• supportive care
• medications to control muscle spasms
• antibiotics and tetanus immune globulin to manage the infection
• wound treatment
• vaccination

Supportive care: Tetanus can have a major impact on your ability to breathe. People who get tetanus usually have mechanically assisted ventilation through a breathing tube. This may involve a tracheostomy, which is a tube inserted directly through a hole cut in the throat.

Because people with tetanus may not be able to swallow, they are usually given nourishment either intravenously or through a nasogastric (NG) tube, which is inserted through the nose, past the throat, and into the stomach. A catheter (tube) may also be inserted in the bladder to drain it.

Medications to control muscle spasms: Medications such as benzodiazepines (e.g., midazolam, diazepam), neuromuscular blocking agents (e.g., vecuronium, pancuronium), dantrolene, or baclofen are given to reduce muscle spasms*.

Antibiotics and tetanus immune globulin: As the consequences of tetanus are due to a toxin produced by the bacteria, an injection of antitoxin is given to the patient. This antitoxin is an antibody preparation that will bind any remaining toxin and prevent it from binding to the nerve cells. They may also need tetanus immune globulin (a blood product from an immune person).

Antibiotics (e.g., metronidazole, penicillin, doxycycline) are used to kill the tetanus bacteria, the source of the toxin, but they are too slow-acting to be the only treatment. If there is an open wound where the tetanus bacteria are thriving, then that wound is surgically cleaned to physically remove any tetanus bacteria.

Vaccination: In people who develop tetanus, the amount of bacteria causing the disease is too small to lead to an effective immune response. This means that these people could get tetanus again. All people who have had tetanus should also receive a tetanus vaccination as part of treatment.

Tetanus is a preventable disease, thanks to the development of a vaccine. When you see a doctor for a cut that might be dirty or infected, the preventive treatment you get depends on your vaccination status. The tetanus vaccine provides good protection for 5 years. Its effectiveness then slowly tails off.

For clean, minor wounds, people who have been vaccinated in the last 10 years don't need any treatment. People who were vaccinated more than 10 years ago get a booster shot of the vaccine, which consists of a weakened form of the tetanus toxin. For deep or dirty wounds, people who received their last tetanus booster more than 5 years ago will need another booster shot.

Those who have never been vaccinated, or have an uncertain vaccination history, need tetanus immune globulin. They also need to be vaccinated against tetanus. People with deep, dirty wounds who have a suppressed immune system (e.g., people with HIV or other immune system problems) will be given tetanus immune globulin.

Children today are normally vaccinated at 2, 4, and 6 months, then again at 18 months and once more around age 4 to 6. Most children will receive a vaccine that protects against tetanus, diphtheria, pertussis, polio, and Hib (Haemophilus influenzae type b) for the doses given at 2, 4, 6, and 18 months of age. A vaccine that protects against tetanus, diphtheria, pertussis (whooping cough), and polio is usually given at 4 to 6 years of age. A further shot, with the adult diphtheria-tetanus-pertussis vaccine, is recommended around age 14 to 16. Adults should continue to get booster shots every 10 years to minimize the risk of tetanus.

Other vaccination schedules may be used for adults or children over 7 years of age who have not been previously vaccinated. Talk to your health care provider for more information.

You can also reduce your risk of tetanus by cleaning all wounds thoroughly, rinsing them with clean water and washing the area around the wound with soap and water. If the wound is deep and dirty, see your doctor.

You might consider wearing knee and elbow pads during sports that are likely to involve violent contact with the ground. Avoid going barefoot while outside of your house. This will help to prevent infection from accidentally stepping on sharp, dirty objects.