What is Anthrax?

Having trouble viewing this email? View it as a Web page.

Minnesota Board of Animal Health Reportable Disease of the Month Header

September 2016


Microscopic view of Anthrax

What is it?

Anthrax is a disease primarily of plant eating animals, including: cattle, horses, mules, sheep, goats, deer, and elk.  It is a naturally occurring disease in animals around the world.  Anthrax was brought to North America by European settlers bringing animal hides, wool, and other goods that carried anthrax spores.  Cattle drives in the 19th and early 20th centuries spread the bacteria in Canada and the U.S.

The disease is caused by a spore-forming bacterium called Bacillus anthracis.  Ruminants are the most likely to contract it from ingesting spores while grazing on pasture.  The spores become active in the animal’s body and the bacteria multiply, which causes illness.

People can get the disease through contact with infected animals or animal products.

How is it transmitted?

Due to the longevity of the Bacillus anthracis spores in certain soils, it can survive many years before being ingested or exposed to animals.  Anthrax usually occurs in Minnesota in mid to late summer and is primarily seen in livestock grazing on pasture.  The specific pathway for exposure is not known but grazing or browsing are potential routes of exposure.  Hay or other dried feedstuffs containing spores have also been identified as a possible route of infection.

Once inside an animal, it can transmit through blood contact between animals and insects.

What are the signs in animals?

In ruminants, there may be signs of high fever, muscle tremors, difficulty breathing, and unclotted blood from any cuts or scrapes.  Many animals are found dead before any indications of the disease, in which case the body may not stiffen after death.

What is the treatment?

If discovered soon enough, the disease can be treated with antibiotic therapy.  Other animals in the herd should be moved off the pasture or away from the area to prevent further exposure to anthrax.  Before returning to the pasture, animals should be vaccinated to protect against anthrax.  Infected and exposed animals are quarantined so there is no chance of exposed or infected animals being moved into the food supply.

How is anthrax in animals diagnosed?

Animals on pasture that die suddenly or are found dead should be examined by a veterinarian to determine if anthrax is a potential cause of death.  Samples can be collected from the carcass and submitted to a laboratory to test for anthrax.

Confirmed cases of anthrax in animals are reportable to the Board.  A follow up investigation of these cases is done to ensure local public health and law enforcement officials are aware of the occurrence of anthrax in livestock in the area.  BAH staff work with the producer to dispose of the carcass in a way that minimizes contamination of the environment from anthrax and to see that other susceptible animals are removed from the area to prevent further animal exposure to anthrax.

Is there a risk to people?

Yes, people who handle animals with infected spores can get a skin infection.  There is also a risk of infection by ingesting spores through consumption of an infected animal.  The greatest risk to people is inhalation of the spores from an animal’s hide or hair.  These risks are all minimal to humans.

How can it be prevented?

Vaccination.  There is an effective vaccine for domestic animals.  It is recommended for use on animals where anthrax has been a problem historically.  The vaccine needs to be administered annually to maintain its effectiveness.