Definition of Inhalation anthrax:

Inhalation (or respiratory) anthrax is an infectious disease caused by breathing in the spores of the bacteria Bacillus anthracis.

Causes, incidence, and risk factors:

Anthrax commonly affects hoofed animals such as sheep and goats, but humans can get sick from anthrax, too. Historically, the main risk factor for getting anthrax was some type of contact with contaminated animal hides, hair, bone products, and wool. Inhalation anthrax was most commonly contracted when workers breathed in airborne anthrax spores, which were released during industrial processes such as tanning hides and processing wool.

Breathing in spores means a person has been exposed to the disease, but it doesn't mean they'll get symptoms. The bacteria spores must "germinate," or sprout ( the same way a seed might before a flower grows) before the actual disease occurs. The process can take up to 60 days.

Once the spores germinate, they release several toxic substances, which cause internal bleeding, swelling, and tissue death.

The main form of inhalational anthrax is a bloody infection of the lymph nodes in the chest, a condition called hemorrhagic mediastinitis. Up to half of affected individuals may also have a hemorrhagic meningitis.