Tetanus is a frequently fatal disease caused by the bacterium Clostridium tetani. The disease is characterized by intense, painful muscle contractions, sometimes strong enough to break even the strongest bones in the body. Reflecting the symptoms of the disease, the word tetanus is derived from the Greek term tetanos, meaning “to contract.” Historically, tetanus had a high mortality rate. With the limited medical treatment available in the 1940s in the United States, for example, the death rate for tetanus was estimated to be over 90 percent.2 Even with intensive medical treatment, the death rate is still 5 to 10 percent.