Anthrax is an often fatal bacterial infection that occurs when the endospores of the bacteria, Bacillus anthraci, are allowed to enter the body through one of three ways.

Cutaneous Anthrax is the most common form of infection and is the result of the endospores entering the body though a cut or abrasion in the skin. Another form, known as Gastrointestinal Anthrax, occurs when the endospores contaminate food, which is then consumed.

Inhalation Anthrax is a third form of infection and is caused by inhaling airborne endospores into the lungs.

Once the endospores are inhaled into the body, they then travel to the lungs where they attach to the tissues of the alveoli. The body then begins to initiate an immune response against the endospores.

Immune cells in the body, called macrophage cells, become alert of the endospores presence and begin to attack by exiting the bloodstream. The immune cells then begin to engulf the endospores as foreign bodies, which is a common immune response.

After the endospores are engulfed, the immune cells enter back into the bloodstream where they travel for a brief time. During this travel, the endospores begin to multiply inside the macrophage cells until they reach there destination inside a lymph gland, one of several areas in the body designed to destroy bacteria.

Inside the lymph gland is where the endospores turn into rod-shaped cells which are then released into the body. It is at this time when the rod-shaped bacteria begin releasing their exotoxins responsible for blood poisoning and pulmonary edema, where the cells in the lung release water and die. This then causes the lungs to fill with fluid resulting in death.