|Anthrax spores can infect humans through a cut or graze, in contaminated meat or by being inhaled. The disease is classified by the way it is caught, so there are three types: cutaneous, gastro-intestinal and pulmonary or inhalation anthrax.
Evidence indicates that man is fairly resistant to anthrax. A study in the early 1960s found that mill workers inhaling up to 1300 spores over 8 hours suffered no ill effects. It is estimated that a human would have to inhale more than 10,000 spores to become infected. Infection will only result if sufficient spores germinate and release harmful toxins.
Signs of the disease usually appear within three days, but in some cases it can be up to two months. An anthrax vaccine is available for people in high risk occupations or for members of the armed forces who may be in danger from biological warfare.