Tetanus is an extremely dangerous infection of the central nervous system. It causes uncontrollable muscle contractions, hence the common name lockjaw.
The disease may be contracted from common, otherwise benign bacteria when a person receives a deep puncture wound. Pieces of rusty iron are particularly prone to this and machinists are at risk.
Tetanus can be effectively prevented with vaccination. However, the tetanotoxin vaccine requires periodic boosters.