Classic anthrax is caused by Bacillus anthracis, which tends to strike ungulates (hoofed mammals) in seasonal outbreaks in arid locales, such as the African savannahs. The bacteria can cause infection in skin, lungs, or intestines. In humans, B. anthracis causes ghastly skin lesions and severe respiratory and intestinal infections—which have mortality rates as high as 85 to 60 percent, respectively.The alternative anthrax bacteria appear to cause an identical anthrax disease in animal models. But, those bacteria aren’t B. anthracis; they’re cousins, B. cereus, commonly found in soil and food. Usually, these are relatively harmless, with some strains known to cause a minor fraction of food poisoning cases. But the ones causing alternative anthrax are different. They just so happen to have gotten their grips on B. anthracis’ virulence plasmids—circular, shareable bits of DNA that contain the genetic code for their disease-causing gene products.