Tetanus
Tetanus, serious infectious disease of the nervous system, in which a bacterial toxin causes severe muscle spasm. Also called lockjaw, the bacterial infection occurs when wounds are contaminated with a bacillus, Clostridium tetani, which is found everywhere but which is especially likely to be present in street dirt. It is an anaerobic bacillus—that is, one that lives without oxygen, and thus when introduced into human tissue, usually at the time of an injury, it can multiply where the oxygen is deficient. This occurs both in deep, penetrating wounds and in crushing wounds with extensive tissue destruction. As the bacillus multiplies, large amounts of exotoxin are released into the surrounding tissues. The incubation period varies from two weeks to several months, but generally is about two weeks. The first symptoms are usually headache and depression, followed by difficulty in swallowing and in opening the jaws. Stiffness of the neck develops and gradually a spasm of the cheek muscles