
Lets have some facts and figures. India among all other countries extremely prone to tetanus. The reason lies in the fact that the agricultural countries provides damp manure treated soils which is perfect place for these bacterias to reside. Hence they spread easily from there.
Clostridia Tetani is the bacteria which causes Tetanus, is an anaerobic bacteria and until and unless they get a oxygen free environment. Rust nails is not the cause for the disease, its the rough surface which provides perfect home for the C.Tetani bacteria spores. These microbes can reside in animal face or any agricultural tools such places. The nails are found dangerous because they cause deep wound, and once this spore gets inside the skin and finds its perfect breeding ground. Once they start their metabolism process, there is no stopping, they start producing toxins that attacks the central nervious system. This cause spasms and muscle rigidity, the prime attacked place is the face.
wiki has a good article on tetanus. The photo curtesey: humanillness.com