Anthrax is a bacterial infection caused by Bacillus anthracis. It usually affects cloven-hoofed animals, such as cattle, sheep, and goats, but it can occasionally spread to humans. Anthrax is almost always fatal in animals, but it can be successfully treated in humans if antibiotics are given soon after exposure. In humans, anthrax is usually contracted when spores are inhaled or come in contact with the skin. It is also possible for people to become infected by eating the meat of contaminated animals. Anthrax, a deadly disease in nature, gained worldwide attention in 2001 after it was used as a bioterrorism agent in the United States. Until the 2001 attack, only 18 cases of anthrax had been reported in the United States in the previous 100 years.

Anthrax occurs naturally. The first reports of the disease date from around 1500 B.C., when it is believed to have been the cause of the fifth...