J.P.
Find out HOW you actually get tetnus. Most people have NO idea, even the doctors giving the shots.
It is an anaerobic bacterium (meaning it can't live in an oxygenated environment) that has to get into a deep puncture wound, not just break the skin and doesn't bleed to push the bacterium out.
Tetanus occurs worldwide but is more common in hot, damp climates with soil rich with manure-treated soils, as the spores are widely distributed in the intestines and feces of many non-human animals such as horses, sheep, cattle, dogs, cats, rats, guinea pigs, and chickens.
The rusty nail cause is somewhat misleading, but that's all people remember hearing.