Anthrax is a colorless, odorless, tasteless bacterium that protects itself from sunlight, heat and disinfectant by forming a protective coat. With this coat, the bacterium is called a "spore." The spores are so small that even an infectious dose - between 8,000 and 10,000 spores - is smaller than a speck of dust.

　　If inhaled, anthrax spores can germinate and lead to infection within one to 60 days. This is pulmonary anthrax, which usually causes death.

　　Less lethal forms include cutaneous infections, which occur if anthrax spores come in contact with a cut or other opening in the skin.

　　Another form of anthrax develops in the intestine of those who eat improperly cooked meat of animals that have been infected with anthrax.

　　Anthrax does not spread from person to person. It is a "one-time agent" - to catch it a person must come directly in contact with the bacterium.

　　Symptoms of pulmonary anthrax are very similar to the flu, which can make an initial diagnosis somewhat difficult. However, in light of recent events many doctors have a heightened awareness of the possibility, and are therefore more likely to diagnose it.

　　Symptoms of the disease vary depending on how the disease was contracted, but usually occur within seven days.