Tetanus is a disease caused by the bacteria Clostridium tetani. Its major effects include stiffness of the jaw (lock-jaw), difficulty swallowing, and general, body wide muscular stiffness. It usually occurs following a major cut or wound. Contrary to common conception, it is not caused by cuts from rusty metal, but more from deeper wounds, like punctures which allow this obligate anaerobe (oxygen avoiding bacteria) to flourish. Rust provides and ideal habitat for Clostridium tetani, explaining why doctors commonly have concerns about Tetanus after such a cut.