Anthrax is an acute disease caused by Bacillus anthracis. It affects both humans and animals and most forms of the disease are highly lethal. There are effective vaccines against anthrax, and some forms of the disease respond well to antibiotic treatment.
Like many other members of the genus Bacillus, Bacillus anthracis can form dormant spores that are able to survive in harsh conditions for extremely long periods of time—even decades or centuries. Such spores can be found on all continents, even Antarctica. When spores are inhaled, ingested, or come into contact with a skin lesion on a host they may reactivate and multiply rapidly.
Anthrax commonly infects wild and domesticated herbivorous mammals which ingest or inhale the spores while browsing—in fact, ingestion is thought to be the most common route by which herbivores contract anthrax. Carnivores living in the same environment may become infected by consuming infected animals. Diseased animals can spread anthrax to humans, either by direct contact (e.g. inoculation of infected blood to broken skin) or consumption of diseased animals' flesh.
Anthrax spores can be produced in vitro and used as a biological weapon. Anthrax does not spread directly from one infected animal or person to another, but spores can be transported by clothing or shoes and the body of an animal that died of anthrax can also be a source of anthrax spores.