Tetanus - Causes
Tetanus is caused by a bacterium called Clostridium tetani. Bacterial spores (the inactive form of the bacterium) are found in soil, street dust, and animal feces. The spores are transmitted to humans through cuts in the skin. Once inside the body, the spores become active. As they grow, they release a toxin (poison) into the blood stream.
Cuts that have not been thoroughly cleaned are the major source of infection. But the disease can be transmitted in other ways also, such as animal scratches and bites, surgical wounds, and dental work.