Tetanus , also known as lockjaw is caused by bacteria found in soil, dust and faeces of domestic animals. Contracting tetanus is greatest in sustaining deep, dirty puncture wounds that do not bleed a lot and an absence of oxygen. Average incubation period is about 10 days. The disease attacks the nervous system, causing fever, headaches, irritability , fatigue, muscle spasms and rigidity, particularly in the jaw, neck and limbs, which can eventually lead to total locking of the jaw, respiratory arrest, heart failure and ultimately death. Tetanus is usually contracted through bacteria spores entering minor wounds and burns via soil, dust or animal faeces, more frequently during the summer or in warm climates.