Anthrax is a highly contagious, rapidly fatal zoonotic disease, caused by the spore-forming bacteria Bacillus anthracis
. Anthrax is an OIE-listed
disease, which is found worldwide, occurring on all continents except Antarctia. It is typically a disease of ruminants and humans.
is shed by its infected host onto the ground, and sporulates when exposed to air. These spores can live in the soil for decades and appears brown and powdery---similar to cinnamon or coca. Bacilli
exhibit an array of physiologic abilities that allow them to live in a wide range of habitats, including many extreme habitats such as desert sands, hot springs, and Arctic soils.
Immunization has led to a global decline in livestock anthrax cases in any parts of the world. Outbreaks are often associated with heavy rainfall, flooding, or drought.
Clinical signs differ depending on the route of transmission of the spores. Inhalation of the spores is the most serious type of infection. Affected animals usually die within 1–3 days, but some animals can survive for up to a week.
Transmission to horses is generally caused by ingestion of the spores while grazing, browsing, or drinking. Other, less likely ways are through inhaling dust containing the spores, direct animal-to-animal contact, biting flies, and human-associated malicious attempts.
The incubation period is generally 1–7 days, but spores can germinate in the lungs up to six weeks post-infection.