Center for Veteranary Public Health Glossary

Anthrax

Bacillus anthracis bacteria (see picture below)
These bacteria can form spores, which are basically “dehydrated” versions of the bacteria. The spores can survive for a long time in the environment, particularly in soil.
Anthrax is a zoonotic disease

A magnified picture of anthrax bacteria
(from the CDC’s Public Health Image Library

Cows	Goats	Sheep

Anthrax spores can be found in soil
When animals graze for food, they can kick the spores from the soil into the air and breathe them in, or they can swallow the spores.
Animals can become very sick and die from the infection
In Maryland, the last time animals were infected and died from anthrax occurred in 1969 on a dairy farm in Kent County; a total of 14 animals died during 1967-1969

Contact with spores can happen naturally by:

Handling animal hides or hair, bone products, or wool from infected animals
Touching or working with infected animals
Contact with spores can happen unnaturally by intentional exposure, such as in a bioterrorist attack, as demostrated in October 2001
Direct person-to-person transmission has not been documented

There are three major forms of human anthrax.

Occurs when spores enter cuts or breaks in the skin
At first, the infection looks like an insect bite, but painless
In 1-2 days, the infection site grows to be 1-3 inches across, with a black area (frequently referred to as an “eschar”) in the center (see picture below)
Nearly 20% of untreated cases result in death, but with medical treatment, death is rare

Cutaneous anthrax sore on a man’s neck
(from the CDC’s Public Health Image Library)

Occurs when anthrax spores are breathed into the lungs
The first symptoms are like a common cold (fever, body aches, tiredness, and headaches)
After several days, severe breathing problems and shock occur; it is frequently fatal
Inhalation anthrax is rare in the US; before 2001, there were only 18 cases in the last 100 years

Occurs when meat from an infected animal is eaten
Early symptoms include nausea, loss of appetite, vomiting, and fever
Later symptoms include abdominal pain, vomiting of blood and severe diarrhea
Death occurs in 25% to 60% of the cases
There have been no confirmed cases of gastrointestinal anthrax reported in the US

People with jobs such as farm workers, veterinarians, tannery and wool workers, and workers who are exposed to dead animals and animal products (hides, hair, wools) from other countries where anthrax is more common
Anthrax infections happen every once in a while in the US, with most reports of infections in animals coming from Texas, Louisiana, Mississippi, Oklahoma, and South Dakota

Some animals (primarily livestock) can be vaccinated; this is the best prevention
In areas where anthrax is common, humans should avoid direct contact with sick livestock and animal products, and avoid eating meat that has not been properly slaughtered and cooked
An anthrax vaccine is licensed for use in humans; it has been reported to be 93% effective in protecting against anthrax disease, however currently there are no recommendations that the general public receive this vaccine

Additional information

Anthrax has been found all over the world, but it is most common in areas that do not have veterinary public health programs, such as South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean, and the Middle East (see map below)


Colored map of natural anthrax distribution around the world (from the World Anthrax Data Site website)
RED = the highest levels of anthrax PINK = high levels of anthrax YELLOW = sporadic anthrax cases	LIGHT GREEN = probably no anthrax DARK GREEN = no anthrax GRAY = unknown