Tetanus is caused by infection with the bacterium Clostridium tetani. The bacterium produces spores that are commonly found in the environment, especially in soil, dust, manure, and animal feces. These spores can enter the body through breaks in the skin, such as cuts, puncture wounds (e.g., from nails or needles), burns, frostbite, or other injuries contaminated with dirt, feces, or saliva

. Once inside the body, particularly in low-oxygen (anaerobic) environments like deep puncture wounds, the spores germinate into active bacteria that produce a potent neurotoxin called tetanospasmin. This toxin interferes with nerve signals controlling muscle contractions, leading to the characteristic muscle spasms and stiffness of tetanus

. Tetanus is not contagious and does not spread from person to person. It most commonly occurs in people who are not vaccinated or have not received booster shots. Newborns and pregnant women in areas with poor immunization coverage are particularly vulnerable, especially through infections of the umbilical stump

. In summary, tetanus is caused by the toxin-producing bacterium Clostridium tetani entering the body through wounds contaminated with spores found in soil and animal feces, leading to muscle spasms and potentially life- threatening complications