Anthrax is primarily a disease of herbivorous mammals, caused by the Gram-positive rod Bacillus anthracis, which causes human infection when its spores enter the body, most commonly from handling infected animals or animal products. The disease occurs in most countries of the world, but is only sporadic where the condition is controlled in livestock by vaccination programmes. Anthrax is a leading agent of biological warfare. After entry into the body, anthrax spores are phagocytosed by macrophages and carried to regional lymph nodes, where they germinate to produce vegetative bacilli that enter the bloodstream. These produce anthrax toxins, which have effects including impairment of cellular water homeostasis and of many intracellular signalling pathways.