Anthrax is a rare disease of animals and humans caused by bacteria called Bacillus anthracis. Anthrax bacteria can live in the soil for many years. Anthrax bacteria occur naturally in the soil in many areas of California but cases of anthrax in animals and humans are very uncommon. Livestock such as cattle, sheep, and goats can become infected when they graze on soil that is contaminated with the bacteria. Animals infected with anthrax cannot transmit the bacteria to other animals or humans. Humans become infected through contact with tissues from an animal that has died of anthrax. In the U.S., human cases of anthrax are seen most frequently in people who handle animal hides and skins, such as wool factory workers, or people who have contact with dead animals, such as farmers and veterinarians. The disease in humans can vary in severity from skin lesions that respond well to treatment, to more severe infections of the lungs or GI tract that can be fatal. Because of its potential for severe, fatal disease, anthrax is a concern as a possible bioweapon agent.