If you haven't had a Tetanus Shot in 10 years and step on a rusty nail then you can get an infection which is a bacterial disease that affects the nervous system and is very often fatal if not treated.
Stepping on a nail and not having a Tetanus Shot to prevent the infection is a serious problem and can kill you within a few days.
You need to keep up on your Tetanus Shots every 10 years and if not you should get a Tetanus Shot if you step on a nail especially a rusty nail.