Once common where livestock were raised, it is now controlled through animal vaccination programs. Anthrax still occurs in countries where animals are not vaccinated, mainly in Africa and Asia. It does occur infrequently in many countries, including the United States. Human infection with anthrax usually results from direct contact with infected animals, or animal products such as wool, meat or hides. However, when anthrax is used as a biological weapon, people become infected by breathing anthrax that is released into the air.
Inhalation anthrax is the disease that results from breathing anthrax.
Under expected battlefield conditions, experts believe you can inhale enough anthrax spores to kill you in one deep breath. Symptoms of inhalation anthrax can begin as early as 24 hours after breathing the spores. Biological weapons are maintained by several countries around the world. Use of these weapons could cause widespread illness among unprotected personnel. Vaccines prevent illness by stimulating the body's natural disease-fighting abilities.