A wound that touches rust does not necessarily mean that you will get tetanus. Tetanus needs an anaerobic environment to survive, and deeper wounds with smaller surfaces are susceptible to tetanus infection.
Tetanus is an acute infection caused by Clostridium tetani, an anaerobic bacterium widely present in the soil and the surrounding environment, and Clostridium tetani survives well in rust.
Because of the anaerobic bacteria, so the wound is closed to the lack of oxygen to be able to reproduce and grow, life is common in the case of rusty nails, the wound is deeper and has not been dealt with is very likely to be infected with the risk of tetanus. The correct approach is to clean the wound in time and inject tetanus antitoxin to neutralize the toxin.
A wound that simply touches rust does not necessarily cause tetanus, but it should be disinfected and cleaned in a timely manner.