Anthrax is a deadly disease caused by the bacterium Bacillus anthracis. It occurs in three forms depending on how the spores enter the body - cutaneous (skin), inhalational (lungs), or gastrointestinal (ingestion). French scientist Louis Pasteur developed the first effective vaccine for anthrax in 1881 after Robert Koch showed in 1876 that B. anthracis caused the disease. The vaccine and understanding of how it spreads helped reduce the suffering from anthrax infections.