A tetanus shot is used to prevent infection by the tetanus bacillus, because certain wounds, such as those that are deep and small or heavily contaminated, are susceptible to colonization by the tetanus bacillus. This bacterium thrives in anaerobic conditions. It typically enters the body through the skin or mucous membranes and produces toxins that cause muscle spasms, a specific type of infection. This often leads to symptoms like lockjaw, spontaneous spasms, and compulsory spasms, commonly affecting the jaw muscles, abdominal muscles, and limbs, and can be life-threatening. Therefore, for wounds that are heavily contaminated, deep, and small, it is essential to administer anti-tetanus treatment.