Anthrax can be contracted from soil or farm animals, particularly goats and sheep, but until recently had not been detected east of the Mississippi River since the 1970s, experts said yesterday.

Dr. Martin Hugh-Jones, a veterinarian and anthrax expert at Louisiana State University, said acidic soil conditions in the Deep South are generally a deterrent to the organism's long-term survival.

That is one key reason, officials said, that law-enforcement officials have become involved in the investigation into how two men working at a newspaper in Boca Raton, Fla., were infected with the disease, which can be deadly if left untreated.

Here is a breakdown on the disease:

Q: What is anthrax?

A: Anthrax, caused by the bacterium known formally as Bacillus anthracis, is a hemorrhagic disease, which means it causes internal bleeding. It is fatal in 95 percent of cases when ingested or inhaled and in 25 percent of cases when contracted through skin.

Q: What are the special features of the bacteria?

A: The bacteria are very hardy. They release spores that can remain viable in a dormant phase in soil or animal products for decades. They also are sometimes found in bone meal. Scientists believe the disease can persist in a dormant phase for more than a century. In most cases, though, the spores are easily killed by sunlight or other sources of ultraviolet light.

Q: Is anthrax contagious?

A: No. It is contracted by direct exposure to active spores. It is not passed from person to person.

Q: So how do people develop anthrax?

A: Usually through contact with animals because the organism thrives on animal hair, wool and pelts. It enters the body through a cut on the skin, on contaminated meat or when spores are inhaled.

Q: Do cases of anthrax occur often in the United States?

A: Sporadically, with more than 90 percent of cases being contracted through the skin. The last such case was reported this year in Texas. In Florida, health officials sometimes confiscate goat skins from the Dominican Republic and incinerate the pelts for fear of contamination. Only 18 inhalation cases in the United States were documented in the 20th century.

Q: What are the symptoms?

A: Initially, symptoms are nonspecific and can be mistaken as the flu. The patient has fever, fatigue, a cough and mild chest discomfort. The patient may show brief improvement, but as the infection spreads, hemorrhaging begins, and vital functions shut down.

Q: How long does it take to see symptoms?

A: It may take as few as 12 hours or as long as 60 days. The usual incubation period is one to seven days.

Q: Are there different levels of the disease?

A: Yes. Two years ago, scientists reported in The Journal of the American Medical Association that lethality is dose-specific. The greater the spore exposure, the greater the likelihood of death. To die of pulmonary anthrax, the type seen in Florida, scientists estimated someone would have to inhale between 2,500 and 55,000 spores.

Q: Is there an anthrax vaccine?

A: Yes, but it is available only to the military.

Q: Are there other treatments?

A: Penicillin has long been used as a treatment. Another antibiotic, ciprofloxacin hydrochloride (brand name Cipro), also is prescribed.

Q: Could anthrax survive in an air-conditioning system?

A: Experts doubt it because the spores do not thrive in water or low temperatures.

Q: Anthrax caused a death at The Sun, a supermarket tabloid, and another employee was exposed. Could spores survive on copies of the paper itself?

A: Experts seriously doubt that possibility.

Q: Why is anthrax associated with bioterrorism?

A: Anthrax spores were made into weapons by the United States in the 1950s and 1960s before the program was ended.

Scientists did this by prodding the bacteria to release all water molecules from their cells, transforming them into hard, tiny beads that withstand a wide range of temperature and weather conditions. In that form, anthrax can be sprayed.