2. ANTHRAX Anthrax bacteria occur worldwide. The organisms known as Bacillus anthraces may ordinarily produce disease in domesticated as well as wild animals such as goats, sheep, cattle, horses, and swine. Humans become infected by contact with infected animals or contaminated animal products. Infection occurs mainly through the skin and rarely by breathing spores or swallowing them. Spores exist in the soil and become active when the organisms in the carcass are exposed to air. Ricin is poisonous if inhaled, injected, or ingested, acting as a toxin by the inhibition of protein synthesis. It is resistant, but not impervious, to digestion by peptidases. By ingestion, the pathology of ricin is largely restricted to the gastrointestinal tract where it may cause mucosal injuries; with appropriate treatment, most patients will make a full recovery