What is tetanus?
Tetanus is an incurable acute disease that occurs when certain bacterial toxins enter the body usually through a wound. It is a serious condition that can even result in death in severe cases. Although there is no cure for it, the condition can still be medically managed until the toxin is “flushed” out of the system. Tetanus can be prevented with adequate immunization.
The incidence of tetanus in the Unites States has drastically decreased since the late 1940s. This is due to the widespread immunization program that requires all young children to be vaccinated against tetanus in early life. lder adults who are not vaccinated or not adequately vaccinated are still at risk of tetanus. Death from tetanus is very uncommon in the United States these days.
Causes of Tetanus
Tetanus is caused by the toxin produced by the bacterium Clostridium tetani (C. tetani). It can form spores which are very resistant to heat, drying and even disinfectants. These spores then reside in soil, animal feces, dust and various other inanimate objects. Sometimes it is also found in human feces. The distribution is global meaning that the bacterium is found throughout the world.
How is it spread?
Contrary to popular belief, tetanus does not only occur outdoors. While wound contact with soil or objects like outdoors for long periods like a rusty nail is more likely to result in tetanus, the bacterium can also be present indoors and enter and wound. Often the injury is minor and may not be given much attention initially. Sometimes it it can even occur with an abrasion, although it is more likely to be seen with a puncture wound or laceration (cut).
Although rare in the United States, tetanus has also been found to be spread through injections into the muscle, tattoos, umbilical cord stump infections in babies, with frostbite, penetrating eye injuries, from dental surgery and dental infections. IV drug users and people with diabetes are at greater risk of developing tetanus. The greatest risk lies among unvaccinated children and traditional practices where soil may be rubbed on the umbilical stump of a newborn.
When there is a deep break in the skin, the bacterial spores can then enter the wound. If the conditions are optimal the spores will germinate into bacteria and release its toxins within the body. There are two toxins that are produced by Clostridium tetani – tetanolysin and tetanospasmin. The former, tetanolysin, does not appear to cause any disease or disturbance within the body. Tetanospasmin is more potent and responsible for the the disease.
What happens in tetanus?
Tetanospasmin is made up of two proteins. One of the proteins attach to the nerve cell and allows the other protein to enter the nerve cell. It then impedes the release of neurotransmitters from the nerve cell (neuron). Neurotransmitters are chemicals that are released at the end of one neuron and then binds to a neighboring neuron. In this way impulses are transmitted across neurons. However, the tetanus toxin prevents this from happening.
The nerves that are affect in tetanus usually inhibit other nerves which causes muscles to contract. As a result these other nerves become hyperactive. The muscles then contract uncontrollably (spasms) and do not relax. Usually this affect is in the region where the bacteria is located and releasing its toxin (localized). However, in severe cases the toxin can travel throughout the body and affect widespread areas of the body (generalized).
Signs and Symptoms
The incubation period for tetanus ranges from 4 to 14 days and is about 7 days on average. Unlike superficial bacterial infections of a wound, the redness, swelling and pain at the site of the infection may not be present. Sometimes the injury and incident where the tetanus bacteria is inoculated at a site may be so minor that a person does not recall the injury.
Tetanus is commonly referred to as lockjaw because it typically affects the muscles of the jaw and neck. Therefore tetanus presents with:
- Muscle stiffness, particularly of the jaw and neck, and also of the abdominal muscles.
- Difficulty swallowing (dysphagia).
- Episodes of painful body spasms that lasts for a few minutes at a time.
- Tachycardia (rapid heart rate) and hypertension (high blood pressure).
Bone fractures may arise as a complication when the muscle spasms are strong and severe. In rare instances the toxin can affect the respiratory muscles from functioning which impairs breathing. This is the reason that death may occur with tetanus. However, it is very uncommon these days.
Treatment and Prevention
There is no cure for tetanus, which is the disease that arises when the toxin binds on nerve cells. However, there are various measures that can prevent tetanus from arising once the bacteria enters the body. Some of these measures can only be effectively implemented after the bacteria enter the body while others, like immunization, can provide lifelong protection. Good wound care at the time of injury and until the wound closes can also play a role in preventing tetanus.
- Antitoxin which can neutralize the tetanus toxin that is not yet bonded to nerve tissue.
- Antibiotics to eradicate the tetanus bacteria but will not act against the toxin.
- Sedatives and other drugs like beta-blockers to control the muscle spasms.
The tetanus vaccine is administered as part of routine childhood immunization programs. It is usually administered in conjunction with shots for other diseases. The DTap vaccine is given as a series of shots from 2 months till about 4 to 6 years. This vaccine includes shots for diptheria, tetanus and pertussis. The tetanus vaccine does not provide permanent immunity and has to be repeated in life.
Booster shots are recommended at around the age of 11 to 12 years. This booster shot may be combination tetanus and diptheria booster (Td), or tetanus, diptheria and pertussis (Tdap). Many adults do not get routine tetanus booster shots but adults who travel internationally should consider it as part of a a travel vaccination regimen. Always consult with a doctor to verify if and when booster shots are necessary.