A highly infectious disease that normally affects animals, especially ruminants (such as cattle, sheep, and horses), but that can be transmitted to humans by contact with infected animals or their products or by biologic warfare. The agent of anthrax is the bacterium Bacillus anthracis. Its spores can resist destruction and remain viable for years. Anthrax is treated with antibiotics such as penicillin, tetracycline, erythromycin, and ciprofloxin (brand name- Cipro). Three forms of disease are caused by anthrax- cutaneous anthrax, inhalation anthrax, and gastrointestinal anthrax.