Tetanus is caused by Clostridium tetani bacteria entering the body through wounds and producing a toxin called tetanospasmin. The toxin travels through the nervous system and causes painful muscle spasms. It is diagnosed clinically based on symptoms like lockjaw and back arching. Treatment involves wound cleaning, antibiotics, controlling spasms, and supportive care. Prevention is through routine tetanus vaccination and boosters after injuries if it has been over 10 years since the last shot. The disease remains a problem globally where vaccination rates are low.