Tetanus and a Rusty Nail

Why do we think that stepping on a rusty nail will give us tetanus? Sure, it will hurt and it’s dirty and scary, but that’s not the only place that you might get tetanus.  It’s not the rust that causes the problem, it’s the bacteria on the nail the nail that does the damage.

Clostridium bacteria, in particular, c. tetani, can be found in the soil, dust, feces and on the skin. These bacteria only reproduce in the absence of oxygen, so if the wound goes deep enough, the bacteria can set up house. The bacteria devlop a spore that is resistant to heat and the usual antiseptics. The spores are widely distributed in the soil and intestines and feces of horses, shoeep, cattle, dogs, cats, rats guinea pigs and chickens. The spores can also be found on skin surfaces and in contaminated heroin.  Tetanus can occur anywherer but is most frequently seen in densely populated areas in hot damp climates with soil rich in organic matter.

Rusty  nails can definitely penetrate deep enough to cause an infection with c. tetani, but so can anything that penetrates the skin deeply such as animal bites, gardening tools, needles and knives.  

Once under the skin, the bacteria produce exotoxins (tetanospasmin and tetanolysin) . Tetanospasmin is a neurotoxin that attacks the central nervous system and blocks nerve signals from the spinal cord to the muscles,  leading to  spasms and muscle rigidity involving the entire body. They can even affect the face. The spasms can be so severe that they can tear msucles or cause spinal fractures. The muslce spasms lead to contortions and unnatural movements. Tetanus comes from the Greek word tetanos, which means “to stretch”. Othe symptoms inlcude drooling, excessive sweating, fever, hand or foot spasms, irritability, difficulty swallowing,  and inability to control urination or bowel movements.

Without treatment, 25% of patients infected die. With proper treatment, only 10% die.

The time between infection and signs of the 1st symptom is generally 7-21 days. The shorter the incubation period, the higher the chance of death. Most cases in the US occur in patients that have not been properly immunized against the bacteria.

Tetanus immunization is given to children but it’s effectiveness dimishes after ten years requiring a booster shot. Most everyone should keep their tetanus immunization up to date.

Treatment consists of antibiotics, tetanus immune globulin, muscle relaxers and sedatives as needed. Often times the wound will need to be debrided. Tetanus immune globulin only helps to remove the unbound tetanus toxin and does not affect toxin already bound to nerve endings.

Tetanus infection is rare in those protected by tetanus immunization. When was your last tetanus booster?

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