Anthony L. Komaroff, M.D.
— DEAR DOCTOR K: What is tetanus? And why do I need a tetanus booster shot?
DEAR READER: When I graduated from medical school, I assumed I would never see a patient suffering from tetanus. It had become unusual since tetanus immunization became available. But it didn't take long for me to see my first case.
A man in his 20s was wheeled into the emergency department by the paramedics. He was strapped to the gurney (a stretcher with wheels). He had to be -- he was having seizures. He was writhing in pain. He would have throw himself off the gurney without the straps.
Above all, I remember his face, his jaw. His mouth was clamped shut. He was breathing through his nose because he couldn't open his mouth. He had tetanus, also called lockjaw. And he was going to die unless we got him the right treatment, fast. We did, and he survived.
Why had he gotten tetanus? Tetanus is caused by an infection with certain bacteria. The bacteria produce a toxin that spreads in the blood through the body and produces severe muscle spasms, cramps and seizures.
The bacteria that cause tetanus can be found almost anywhere. They are especially common in the soil and manure of farms. But they also contaminate dust in cities, the dirt of suburban gardens and dirty floodwaters.
A tetanus infection may develop after almost any type of skin injury, major or minor. This includes a dirty puncture wound, cut, scrape, burn, animal bite or some other break in the skin. Tetanus also can develop after body piercing, tattooing, an insect sting or even a tiny splinter. The patient who introduced me to tetanus was an intravenous drug abuser, who shoved a lot of dirty needles into his skin.
The other reason that patient got tetanus was that he hadn't had a tetanus shot since he was a young child. In the United States, babies are immunized against tetanus through a series of four vaccinations. Children then receive two tetanus booster shots between the ages of 4 and 12. After age 12, a tetanus booster shot usually is recommended every 10 years.
Why are booster shots necessary? Because the immunity provided by a tetanus booster shot begins to wane after five to 10 years. Booster shots enhance, or boost, tetanus immunity. They ensure that you continue to be protected.
In some cases, your doctor may give a booster dose after fewer than 10 years -- for example, if you get a severe cut or puncture wound, and it has been more than five years since your last tetanus shot. I think intravenous drug abusers should get tetanus shots every five years.
If you are regularly exposed to dirt, dust, manure or dirty water, be especially careful to keep your tetanus shots up-to-date. This would apply if you are a farm worker, veterinarian, landscaper, gardener, firefighter, or if you are exposed to sewage or floodwater.
If it has been more than 10 years since your last tetanus booster, schedule an appointment with your doctor.
Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.
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