Anthrax is an acute disease caused by the bacterium Bacillus anthracis. Most forms of the disease are lethal, and it affects mostly animals. It is not contagious but can be transmitted through contact or consumption of infected meat. Effective vaccines against anthrax are available, and some forms of the disease respond well to antibiotic treatment. Anthrax commonly infects wild and domesticated herbivorous mammals that ingest or inhale the spores while grazing. 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.