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Tetanus in developing nations still accounts for hundreds of thousands of death worldwide. Vaccination in the developed world has made tetanus extremely rare.
Mysteries of the Tetanus Shot
Sean Nordt MD, PharmD, Stuart Swadron MD, Rob Orman MD and Ran Ran MD
Highlights
Tetanus is seen infrequently in the western world but it still accounts for much morbidity and mortality, including in neonates, in the developing world.
Tetanus is caused by Clostridium tetani. Tetanus inhibits the release of glycine and GABA. These are inhibitory neurotransmitters. This causes the classic opisthotonus and leads to respiratory arrest. Another Clostridium bacterium, botulism, inhibits the release of acetylcholine.
Opisthotonus is severe arching of the back. This occurs because the extensor muscles of the back are much stronger than the flexor muscles in the front. All of these muscles are firing and the back wins. This is not subtle. If you see this, also consider strychnine poisoning. Strychnine poisoning inhibits the binding of glycine in the spinal cord and presents similarly.
Do tetanus vaccinations work? Yes. The vaccination was first introduced during World War I. Prior to its introduction, about 1 out of every 300 soldiers contracted tetanus. There was a thirty-fold decrease in the incidence of tetanus in the subsequent two months. In the 1940s, it was introduced as a routine vaccination in children. Since then, the rate of tetanus has dropped thirty-fold in the civilian population.
The primary series of three vaccines during childhood educates your immune system to recognize the pathogen, and this is followed by a booster shot every 10 years for the rest of your life. Although this has not been well studied, the Centers for Disease Control (CDC) found that 100% who adhere to this regimen will have antibodies at a protective level.
Can people who have had the vaccine still get tetanus? Yes. Titer level is only one component: the pathogen burden and immune system function also contribute.
In a review of all tetanus cases between 2001-2008 released by the CDC, 70% of wounds were considered prone to tetanus, such as contaminated wounds or puncture wounds. 30% were clean wounds and there have been case reports of surgical wounds, using autoclaved instruments, resulting in tetanus.
When does immunity start to wane? Increased age leads to decreased immunity. In the United States, there have not been any neonatal cases of tetanus and only 1-2 cases in patients under 20 years old. The booster is very important in older individuals. Tetanus is a unique pathogen, and recovering from clinical tetanus doesn’t convey immunity. The tetanus toxoid is one of the most potent toxins known to man. The lethal dose is 2.5 ng/ kg. It is important to keep a supratherapeutic level of antibody titers, as it is important for protection. Diabetes, HIV, and prednisone can also weaken the immune response.
CASE
You are working at your Emergency Department on Saturday night. A 30-year-old male stepped on a rusty nail. He had all of his immunizations and boosters for college. Does he need to get a tetanus shot immediately or can he wait until Monday?
Irrigation and debridement of necrotic tissue are the most important intervention. Tetanus vaccine is terrific as primary prevention before an exposure, but it doesn’t do much as secondary prevention.
The tetanus booster is available as Tdap (tetanus diphtheria and pertussis) and Td (tetanus diphtheria). The CDC recommends that everyone receive a tetanus booster every ten years, and one of those doses should be Tdap after the age of 18 years. Pregnant women should receive Tdap with every pregnancy. Giving elderly patients Tdap is not cost effective but would reduce the likelihood of the patient developing pertussis by 25%. Tdap is twice as expensive as Td ($50 versus $25).
Who is likely to develop tetanus despite vaccination? Immunity wanes with age. Most of the cases of clinical tetanus happen in the elderly.
There is no herd immunity; tetanus is infectious but not contagious.
Don’t forget about tetanus in open fractures and ocular injuries. If you are worried about tetanus, metronidazole or penicillin are the recommended antibiotics.
Sean G., M.D. - July 2, 2015 3:40 AM
I dont understand the logic behind treating the not UTD pt with TIG in addition to the vaccine for "tetanus prone wounds" when the bloggers mentioned nearly 1/3 of tetanus wounds were "clean wounds" some even surgical "by autoclaved instruments" if that is true being "tetanus prone" is a sort of non sequitur, unless we find missing nearly 1 in 3 acceptable...it would seem from the argument posed by the discussion one would want to treat all wounds in the non utd individual with TIG...am I missing something?
Athanasios T., Dr - July 12, 2015 1:04 PM
Simple corneal abrasions do NOT require tetanus prophylaxis
Mukherjee P, Sivakumar A. Tetanus prophylaxis in superficial corneal abrasions. Emerg Med J. 2003;20(1):62–64.
Gregory T. - August 9, 2015 11:41 AM
From that study: "... there are no case reports in the
literature of clinical tetanus developing from a simple corneal
abrasion."
Richard P. N. - July 24, 2015 12:32 PM
No documented cases of tetanus from a corneal abrasion. Tetanus immunity status becomes an issue if there is a penetrating injury to the eye. So it's OK if the rusty nail scratches your eye, and not OK if it penetrates into the eye.