Understanding Tetanus -- The Basics

What Is Tetanus?

Tetanus is a dangerous nerve ailment caused by the toxin of a common bacterium, Clostridium tetani. Bacterial spores are found in soil -- most frequently in cultivated soil, least frequently in virgin soil. The spores can remain infectious for more than 40 years in soil. They also exist in environments as diverse as animal excrement, house dust, and the human colon. If the spores enter a wound that penetrates the skin and extends deeper than oxygen can reach, they germinate and produce a toxin that enters the bloodstream.

This toxin, tetanospasmin, ranks with botulism toxin as among the most potent known microbial poison. It is taken up from the blood by the outermost nerves and moves inward toward the spine. After approximately eight days (ranging from three to 21 days), it begins to short-circuit nerve signals and block the relaxation of muscles. This results in sustained muscle contractions, notably the lockjaw for which tetanus is nicknamed.

Spasms of the jaw or facial muscles may follow, spreading to the hands, arms, legs, and back and blocking the ability to breathe. Spasms are often precipitated by noise or touch. Once tetanus has spread, the mortality rate is approximately 30%, even in modern medical facilities.

Tetanus is not contagious from person to person.

In developing countries, about 34 000 newborns died from neonatal tetanus in 2015. This a 96% reduction since 1988, primarily because of large-scale immunizations.

Since childhood immunization laws were passed in the U.S. in the 1970s, only about 50 cases a year are reported in this country; about three-quarters are elderly people or people who have never been immunized.

What Causes Tetanus?

Bacterial spores enter the body by way of animal or insect bites, surgical wounds, needle injection sites, burns, splinters, ulcers, and infected umbilical cords -- and by the proverbial rusty nail. Be particularly suspicious of any wound caused by a dirty or dusty object that has been outdoors or in contact with soil.

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