By Erin K. Costello
Lately we have seen more and more posts regarding possible tetanus exposure. This disease is especially troubling because unlike with some of the other vaccine preventable diseases, you do not build up an immunity after having survived tetanus. The advice we have been witnessing being offered in anti-vaxer groups is troubling, especially the assurance of not needing medical attention, and/or a possible tetanus shot. These posts and comments are grossly innacurate, and dangerously negligent. But before we get to correcting their suggestions, let’s first learn about tetanus. To understand how tetanus occurs, how it can be prevented, and what can be done upon possible exposure, lets first understand what tetanus is and how it effects the human body.
Clostridium tetani is an obligate, anaerobic, motile, gram positive bacillus. Which basically means it’s a bacteria able to live under one set of conditions, in the absence of oxygen, is able to move on its own independently through metabolic energy, and/or spontaneous moving spores, and has a cell wall containing a high level of peptidoglycan (a polymer composed of sugars and amino acids), allowing the cell wall to interact with the environment of the bacteria, specifically the infected tissue of the host. This cell wall will also help shape the cell, will help protect it against damage such as mechanical pressure and bursting because of osmosis, as well as provide transport for molecules to cross the cell membrane. It is a nonencapsulated bacteria that forms heat resistant spores that are resilient to desiccation (extreme dryness), as well as disinfectants. These spores are often found in human and animal feces, animal intestines, soil, and even house dust. Spores have been known to survive in normal tissue for months, even up to years. In order for the spores to grow and develop they require dead or dying tissue, foreign body, and/or an already present infection. These conditions can create the ideal environment, which consists of wounds with a potential of low oxygen (the preferred habitat). Under these ideal conditions the spores may release their toxins upon germination. The infection site will often appear normal or without irritation since C tetani fails to cause inflammation.
SYMPTOMS AND TYPES OF TETANUS
Tetanus is described as a severe onset of hypertonia (rigid muscles) and painful muscle spasms or contractions, in the absence of other possible causes explained by medicine.
Tetanus is often clinically labeled into four types:
1) Generalized tetanus, which usually presents with trismus, or “lockjaw", nuchal rigidity, and dysphasia (difficulty speaking). These symptoms can then cause risus sardonicus (facial paralysis). As the illness progresses patients will feel intense pain due to an intact senses. The pain is often caused by muscle rigidness, stimulated reflexive spasms, and opisthotonos (neck and spine arching) from tonic contractions. These episodes can cause bone fractures, tendons to rupture, and respiratory distress or failure.
2) Localized tetanus, which is persistent muscle rigidity near the site of injury caused by dysfunctional interneurons that obstruct the alpha motor neurons for these muscles. This type presents with low mortality rates.
3) Cephalic tetanus, which is quite uncommon and often manifests itself after head trauma or otitis media (middle ear infection) by presenting symptoms of cranial nerve (CN) palsies. This type may become and remain localized or may become generalized.
4) Neonatal tetanus, which is caused by the contamination of the umbilical cord due to unsanitary conditions upon delivery, as well as lack of immunization in the birth mother. Within the first 7 days of life, infants who are infected are unable to feed properly, are irritable, and form rigidity with spasms. Chances of survival are poor.
WHAT HAPPENS INSIDE THE BODY ONCE INFECTED
Once infected, germinating spores release two toxins:
-Tetanolysin, which is a toxin that destroys red blood cells.
-Tetanospasmin, which is the cause of how tetanus manifests itself in the human body. It is also one of the most potent toxins known. A minimum lethal dose is about 2.5 ng/kg body weight (for a 55 kg/120lb person that’s 0.0000001 grams!)
Tetanospasmin is then synthesized in to a 150-kD protein made up of a 100-kD heavy chain and a 50-kD light chain connected by a disulfide bond. The heavy chain controls binding of Tetanospasmin to the presynaptic motor neuron, creating a pore for the light chain to enter into the cytosol. Once the light chain is inside the motor neuron, it moves from the site of infection to the spinal cord by way of retrograde axonal transport (inside the cell), usually within 2-14 days. It then enters central inhibitory neurons as the light chain binds to vesicles of the cell membrane of neurotransmitters. As a result, there is a loss of inhibitory action as gamma-aminobutyric acid (GABA)- (which transmits signals) is prevented from being released. This loss of this inhibition causes uncontrolled muscle spasms and autonomic hyperactivity to be stimulated by normal daily occurrences such as noise and light.
Once the tetanospasmin is locked to neurons, it is resilient to an antitoxin. The only way for recovery to occur is for new nerve terminals to grow and form new synapses.
U.S. TETANUS DATA AND FACTS
In some conditions, tetanus spores can live for years and are resistant to disinfectants, as well as boiling for up to 20 minutes. However, surviving vegetative cells can be easily inactivated and are vulnerable to many antibiotics.
Tetanus is found both outdoors and indoors. The contamination site is often (65%) a minor wound that is rarely tended to medically. About 5% of the time the source is due to chronic skin ulcers, and the remaining cases present no obvious cause.
There are also cases of tetanus caused by complications to persistent conditions such as gangrene and an abscess. It can also infect damaged tissue from burns, frostbite, middle ear infections, dental procedures, surgical procedures, abortion, childbirth, and IV drug use.
A significant cause of tetanus is underimmunization, i.e. those not immunized, those partially immunized, or those fully immunized but have failed to receive booster shots. Tetanus cannot be spread directly from one person to another though.
Only 12-14% of US tetanus patients had received the primary round of the tetanus vaccine. During the years 1998-2000, just 6% of all US tetanus patients were up to date with their tetanus vaccinations, and there were no fatalities in this group. Additional data from this time showed:
— 73% of US tetanus cases were due to an acute injury, such as puncture wounds (50%), lacerations (33%), and abrasions (9%).
—Of the puncture wounds, 32% were from stepping on a nail.
—Tetanus occurred in burn victims, those receiving IM injections, people receiving tattoos, those with frostbite, dental infections, penetrating eye injuries, and infections at the stump of the umbilical cord.
—Reported risk factors also listed were diabetes, persistent skin wounds such as ulcers, drug use, and recent surgery (4% of US cases).
—During this time frame 12% of US tetanus patients had diabetes (mortality at 31%), as opposed to 2% during the years 1995-1997, of these patients, 69% had acute injuries and 25% had gangrene or an ulcer caused by diabetes.
—After surgery tetanus had a median time frame of 7 days.
—US tetanus cases were reported after removal of a tooth, a root canal, as well as trauma to the intraoral soft tissue.
WHAT TO DO IN THE EVENT OF POSSIBLE EXPOSURE
The incubation period for tetanus does vary between 3-21 days. However, the further the site of exposure is from the central nervous system, the longer the incubation period lasts. With shorter incubation periods the risk of death is higher.
It is important that any wound having possibly been exposed to tetanus be tended to ASAP. Medical treatment depends on the individual’s tetanus vaccine status and their type of injury. In every case the wound should be cleaned, and treatment should be sought right away.
For injuries that present as possible exposure to tetanus, a patient with an unknown or incomplete history of required tetanus shots needs to be given a tetanus and diphtheria shot (Td or Tdap), as well as a shot of tetanus immune globulin (TIG) immediately.
A person with a known history of a complete series of three Td or Tdap shots and who last received a booster within 10 years should already be protected. However, if their last booster was over 5 years ago they may still be given a booster shot at the time to help insure they are protected.
There is no cure for tetanus, surviving the disease is excruciatingly painful, and sometimes ends in death. This is why it is important for those possibly exposed to seek immediate medical treatment, opt for the vaccine, and if necessary insist on the tetanus immune globulin dose. These are your best chances at avoiding the contraction of tetanus, as well as surviving tetanus if you do fall victim to the disease.