tetanus (tĕt´nəs, –ənəs) or lockjaw, acute infectious disease of the central nervous system caused by the toxins of Clostridium tetani. The organism has a widespread distribution and is common in the soil, human and animal feces, and the digestive tracts of animals and humans; however, the toxin is destroyed by intestinal enzymes. Infection with the tetanus bacillus may follow any type of injury, whether incurred indoors or out, including nail puncture wounds, insect bites, splinter injuries, gunshot wounds, burns, lacerations, and fractures. Deep puncture wounds are most dangerous, since the bacillus thrives in an anaerobic environment.
The tetanus toxin, one of the most potent poisons known, acts on the motor nerves and causes muscle spasm at the site of infection and in other areas of the body. The most frequent symptom is stiffness of the jaw (lockjaw) and facial muscles. Difficulty in breathing and severe convulsions may ensue. The mortality rate is very high, especially in the very young and the aged; overall it is about 40%. Treatment with tetanus antitoxin should be started promptly in conjunction with human immune globulin. It is preferable, however, to prevent the disease by active immunization (including booster shots) with tetanus toxoid (see vaccination).