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 occurs 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.
Inhalational anthrax is the disease that results from breathing in anthrax spores.
Under expected battlefield conditions, experts believe you can inhale enough anthrax spores to kill you in one deep breath. Symptoms of inhalational anthrax can begin as early as 24 hours after breathing the spores. Initial symptoms include fever, cough, and weakness. These ultimately progress to breathing problems, shock, and death. Vaccines prevent illness by stimulating the body's natural disease-fighting abilities.