Anthrax infection. Light micrograph of tissue infected by anthrax bacteria (Bacillus anthracis, rods). Anthrax affects humans and livestock. There are 3 main forms of the disease. Cutaneous (skin) anthrax causes a raised, itchy lesion at the site of entry of the bacteria. Antibiotic drugs can cure the disease, although it may be fatal if left untreated. Gastrointestinal anthrax is more serious, causing vomiting of blood and severe diarrhoea. Pulmonary (lung) anthrax, caused by inhaling the bacteria, is fatal in most cases unless treated soon after exposure. In 2001, a series of postal anthrax attacks in the USA killed five. Magnification unknown.