Tetanus

Tetanus is an acute, often fatal, disease caused by a toxin, called tetanospasmin that is produced by the germ, Clostridium tetani. The frequency of Tetanus in the U.S. has decreased dramatically in the past 60 years so that the average annual occurrence is now about 50 cases per year; the highest numbers being reported from California and Texas.

Tetanus is an acute, often fatal, disease caused by a toxin, called tetanospasmin that is produced by the germ, Clostridium tetani. The frequency of Tetanus in the U.S. has decreased dramatically in the past 60 years so that the average annual occurrence is now about 50 cases per year; the highest numbers being reported from California and Texas. Also, mortality rates have dramatically decreased from 90% fifty years ago to 16% in the U.S. now. Even though Tetanus is not common in the United States, when patients in the U.S. contract Tetanus, one in six dies, usually after a very long, miserable hospital course.

The Clostridium tetani germ typically exists as a spore until it gets buried into the tissues of a wound from a laceration, puncture, abrasion or skin tear. Less common causes of the tetanus spores gaining entry into tissues include burns, tattoos, frostbite, boils (abscesses – including dental), root canal surgery, a cut inside the mouth and tooth extractions. Once the spores are buried in tissues that are not exposed to air (oxygen); in the low oxygen state, they change from spores to germs, and then the germs produce their toxin. The presence of a low oxygen state enhances the formation of germs from spores. That is why wounds that are deep or punctures are at higher risk for developing Tetanus.

Clostridium spores are found nearly everywhere, but predominately in dirt, animal feces, and animal and human intestinal tracts; so wounds contaminated by this type of material are at higher risk for causing Tetanus. The spores are extremely hardy – they can survive for months in the soil and withstand high temperatures and common disinfectants. Once the germ creates the toxin, it binds to nerves in the tissues. After binding to the nerves, the toxin progresses up the nerve to the spinal cord or brain. As the toxin binds to the nerves, it prevents those nerves from functioning normally – this results in increasingly frequent bouts of spasm of whichever muscles the nerves affect. Once the brain/spinal cord are involved, the facial muscles develops rigidity (hence the term “lockjaw”), followed by muscles of the neck, arms, chest, abdomen and then legs. Severe spasm of the neck and chest muscles is not only extremely painful, it also prevents swallowing and eventually breathing. The amount of toxin necessary to cause Tetanus is incredibly small - only 0.00000000175 grams (175 nanograms)!

Unfortunately, the nerves connected to muscles are not the only nerves afflicted. The nerves that control the autonomic (automatic) nervous system also go “haywire”, so that control of heart rate, blood pressure, temperature and sweating become highly labile and difficult to control.

Tetanus can produce one of three recognizable forms:

1. localized Tetanus – this unusual form (1% of cases) of the disease causes affliction of only the nerves/muscles in the area of the wound. The toxin does not make it into the brain or spinal cord. The result is persistent, painful spasms of the muscles around the wound site. This form of Tetanus typically persists from weeks to months.

2. cephalic (head) tetanus - this is another uncommon form of Tetanus that occurs as a result of chronic middle ear infections or a localized head wound. In this type of Tetanus, the symptoms remain localized to the head and/or face area and usually last for weeks to months.

3.generalized tetanus - accounts for the vast majority of cases, presenting with the descending pattern of severe muscle spasms – from head to face to neck, chest, arms, abdomen, legs; and the out of control heart rate, blood pressure, temperature & sweating from loss of autonomic nervous system control. The illness last weeks to months, and if the patient survives, they often have chronic disabilities.

Generalized Tetanus can also occur in a newborn child (neonatal Tetanus). This occurs in newborns of mothers who have not been adequately immunized against Tetanus. This is a very common form of Tetanus throughout the world, but rare in the U.S. because of high rates of immunization here. There have been only 2 reported cases of neonatal Tetanus in the U.S. since 1989.

Since Tetanus is uncommon and the symptoms are initially non-specific, the diagnosis can be very difficult to make. Additionally, there is no specific lab or x-ray tests that make the diagnosis; so it must be made on clinical grounds only. The incubation period after the spores are in the wound until the symptoms start is variable but averages 8 days. Typically, the closer to the head and the larger number of spores deposited – the earlier the disease starts, and the worse outcome is.

Once contracted, Tetanus is a terrible disease to go through. Patients are treated with tetanus immune globulin which prevents any further toxin absorption, but it can not stop the toxin that has already been absorbed by the nerves. Therefore, further treatment is aimed at reducing the intensity of muscle spasms, controlling heart rate and blood pressure, and supporting ventilation. Patients are almost always severely ill and require intensive care for weeks, often requiring paralysis and a ventilator to breathe. Thirty percent of patients who need a ventilator die.

Since Tetanus is such a severe disease, every effort should be made at prevention. Vaccination is the mainstay of prevention of Tetanus. Children should receive DTaP (diphtheria, tetanus and acellular pertussis) shots at 2, 4, 6 and 15-18 months. Booster shots should be given at 4-6 years and at 11-12 years of age, and every 10 years thereafter. Any wound that is judged by a physician to be “Tetanus prone” – for example, a deep or puncture type wound or if heavily contaminated, contaminated with dirt from a field with animals or human feces, or likely to have bits of contamination not removable from the wound; should have a booster if it has been greater than 5 years since the last booster. It can be said with nearly 100% certainty that an adequately immunized person will not contract Tetanus.

This article is intended to provide useful information, not medical advice. This information cannot, and is not meant to, replace consultation with your physician regarding your individual circumstances.