Anthrax is a serious disease caused by the bacterium Bacillus anthracis. While anthrax most often occurs in animals (such as cattle, sheep, and goats), it can also affect humans. There are three major types of anthrax: cutaneous (skin) anthrax, inhalation anthrax, and gastrointestinal anthrax. Roughly 95 percent of anthrax infections are cutaneous anthrax. Anthrax transmission generally occurs in one of two ways: from animals, or as the result of a biological weapon. Anthrax is not, however, spread from one person to another. Also, in an average year, the risk of any one individual in the United States contracting anthrax is extremely low (about 1 in nearly 300 million). Anthrax treatment usually involves antibiotics, and providing relief of symptoms and complications as the body fights the anthrax bacteria.