Anthrax spores can enter the body through:
- Inhalation into the lungs (inhalation anthrax) - The spores can be inhaled in contaminated soil or other particles containing the spores. The spores have no smell, taste or color, so a person would not notice anything had happened unless the spores had been mixed into a substance that could be readily seen, smelled or tasted. In order to enter the lungs, where they can germinate, the spores have to be very small -- from 1 to 5 microns (millionths of a meter). According to an anthrax report published by the American Medical Association, at least 2,500 spores have to be inhaled to cause an infection.
- Entry into a cut or opening in the skin (cutaneous or skin anthrax) - Open cuts and scrapes can allow entry of the spores into the body to an environment in which they can germinate. This type of anthrax may also be spread by biting insects that have fed on infected hosts. The head, arms and hands are most often affected. People who handle contaminated animal products such as leather, hair (particularly goat hair) and wool are often exposed to the anthrax bacteria. Cutaneous anthrax accounts for about 95 percent of cases worldwide. If untreated, it has a fatality rate of five to 20 percent. If treated with antibiotics, it rarely leads to death.
- Entry through the gastrointestinal tract (gastrointestinal anthrax) - Eating undercooked meat that is infected with the anthrax bacteria, or drinking unchlorinated water that harbors the spores, can introduce the bacteria into the gastrointestinal tract. Infection can occur in either the upper or lower GI tract. This form of anthrax is rare.