Bacillus anthracis has a wide host range among warm-blooded animals and causes the disease anthrax. This manifests in localized forms (skin, alimentary) and as septicaemia, the latter typically being fatal. Bacillus anthracis forms robust and long-lived endospores, which constitute the environmental phase of its lifecycle and are the key infective agents. Elaboration of plasmid-encoded binary toxin complex and a capsule are fundamental to pathogenicity. Epidemiology in animals is typified by prolonged environmental quiescence and acute systemic disease. Human disease is non-contagious and derives usually from contact with livestock or animal products, although military or terrorist dispersal of spores remains a threat.