Anthrax: What you need to know

(CNN) -- As concern about anthrax spreads across the world, here are some key questions and answers about the disease.

1. What is anthrax?

Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. It most commonly occurs in mammals such as cattle, sheep, goats, camels and antelopes, but can also occur in humans when they are exposed to infected animals or tissue from infected animals.

2. How common is anthrax and who can get it?

Anthrax is most common in agricultural regions where it occurs in animals. Humans infected with anthrax usually have been exposed to infected animals or their products through their occupations. Workers who are exposed to dead animals and animal products from other countries where anthrax is more common may become infected with Bacillus anthracis.

3. How is anthrax transmitted?

Anthrax infection can occur in three forms: cutaneous (skin), inhalation, and gastrointestinal. Spores can live in the soil for years, and humans can become infected with anthrax by handling products from infected animals or by inhaling anthrax spores from contaminated animal products. Eating undercooked meat from infected animals also can spread the disease. It is rare to find infected animals in the United States.

4. What are the symptoms of anthrax?

EXTRA INFORMATION In Depth: The anthrax investigation

They vary depending on how the disease was contracted, but symptoms usually occur within seven days.

- Cutaneous: About 95 percent of anthrax infections occur when the bacterium enters a cut or abrasion on the skin, such as when handling contaminated wool, hides, leather or hair products of infected animals. It begins as a raised itchy bump that resembles an insect bite, but soon turns into a painless ulcer, usually one to three centimetres in diameter, usually with a black centre in the middle. Lymph glands in the adjacent area may swell. About 20 percent of untreated cases result in death. The employee at NBC who contracted anthrax has cutaneous anthrax.

- Inhalation: Initial symptoms may resemble a common cold, but lead to severe breathing problems and shock after several days. Inhalation anthrax is usually fatal. An employee of a Florida tabloid publishing company contracted inhalation anthrax and died.

- Intestinal: This form of anthrax may follow the consumption of contaminated meat and is characterised by an acute inflammation of the intestinal tract. Initial signs include nausea, loss of appetite, vomiting and fever, followed by abdominal pain, vomiting blood and severe diarrhea. Between 25 percent and 60 percent of cases are fatal.

5. Where is anthrax usually found?

Anthrax is global. It is more common in developing countries or countries without veterinary public health programs. Certain regions of the world (South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean, and the Middle East) report more anthrax in animals than elsewhere.

6. Can anthrax be spread from person to person?

Direct, person-to-person spread of anthrax is extremely unlikely. It is not contagious.

7. Is there a treatment for anthrax?

Doctors can prescribe effective antibiotics. To be effective, treatment should be initiated early. If left untreated, the disease can be fatal.

8. Is there a way to prevent infection?

In countries where anthrax is common and vaccination levels of animal herds are low, humans should avoid contact with livestock and animal products and not eat meat that has not been properly prepared.

Also, an anthrax vaccine has been licensed for use in humans. It is reported to be 93 percent effective.

9. What is the anthrax vaccine?

It is a cell-free filtrate vaccine, which means it contains no dead or live bacteria in the preparation. Anthrax vaccines intended for animals should not be used in humans.

10. Who should get vaccinated against anthrax?

-- People who work directly with the organism in the laboratory

-- People who work with imported animal hides or furs in areas where standards are insufficient to prevent exposure to anthrax spores.

-- People who handle potentially infected animal products in high-incidence areas.

-- Military personnel deployed to areas with high risk for exposure to the organism (as when it is used as a biological warfare weapon).

Pregnant women should be vaccinated only if absolutely necessary.

*Information from the Centers for Disease Control and Prevention in Atlanta, U.S.