Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. It most commonly occurs in mammal such cattle, sheep, goats, camels and antelopes, but can also occur in humans when they are exposed to infected animals or tissue from infected animals. Anthrax is a colorless, odorless, tasteless bacterium that protects itself from sunlight, heat and disinfectant by forming a protective coat. With this coat, the bacterium is called a "spore." The spores are so small that even an infectious dose — between 8,000 and 10,000 spores — is smaller than a speck of dust.

If inhaled, anthrax spores can germinate and lead to infection within one to 60 days. This is pulmonary
anthrax, which usually causes death. Less lethal forms include cutaneous infections, which occur if anthrax spores come in contact with a cut or other opening in the skin.

Another form of anthrax develops in the intestine of those who eat improperly cooked meat of animals that
have been infected with anthrax.

All three forms of anthrax disease can be caused by the same bacterium — Bacillus anthracis.

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.

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.

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 centimeters in diameter, usually with a black center 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 characterized 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.

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.

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

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

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.

It is manufactured and distributed by BioPort Corp. of Lansing, Michigan. 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.

The CDCP's advisory committee on immunization practices recommends vaccination for the following:
             - 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.
               (Incidence is low in the United States, but veterinarians who travel to work in other
               countries where incidence is higher should consider getting vaccinated.)

             - 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.

Anthrax does not spread from person to person. It is a "one-time agent" — to catch it a person must come
directly in contact with the bacterium.

Symptoms of pulmonary anthrax are very similar to the flu, which can make an initial diagnosis somewhat
difficult. However, in light of recent events many doctors have a heightened awareness of the possibility, and
are therefore more likely to diagnose it.

Symptoms of the disease vary depending on how the disease was contracted, but usually occur within seven days.
The Centers for Disease Control list the following:

                 Cutaneous: Most (about 95 percent) 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 (especially goat hair) of infected animals. Skin infection
                 begins as a raised itchy bump that is dark in color and resembles an insect bite but
                 within 1-2 days develops into a vesicle and then a painless ulcer, usually 1-3
                 centimeters in diameter, with a characteristic black area in the center. Lymph glands
                 in the adjacent area may swell. About 20 percent of untreated cases of cutaneous
                 anthrax will result in death. Deaths are rare with appropriate therapy.

                 Inhalation: Initial symptoms may resemble a common cold. After several days, the
                 symptoms may progress to severe breathing problems and shock. Inhalation anthrax
                 is usually fatal.

                 Intestinal: The intestinal disease form of anthrax may follow the consumption of
                 contaminated meat and is characterized by an acute inflammation of the intestinal
                 tract. Initial signs of nausea, loss of appetite, vomiting, fever are followed by
                 abdominal pain, vomiting of blood, and severe diarrhea. Intestinal anthrax results in
                 death in 25 percent to 60 percent of cases.

Antibiotics, including Ciprofloxacin (sometimes shortened to "cipro") and penicillin can be effective if administered
after infection. For pulmonary anthrax, the drugs must be administered very soon after infection.

Only one American company, BioPort Corporation of Lansing, Mich., is licensed to produce an Anthrax vaccine right now. Robert Kramer, President and COO of BioPort said that they have enough vaccine to support the anthrax vaccination immunization program that is currently sponsored by the Department of Defense, and at some point in the future, they will have additional vaccine available for civilian use.

BioPort plans to file papers to ship new Anthrax vaccines next year, but the drug, as planned, would not be safe for children, pregnant women or the elderly.

Critics of the vaccine have raised many questions about its safety. More than 400 members of the military have either quit or faced court-martial rather than take the anthrax vaccine for fear of side effects reported, such as extreme fatigue, headaches, muscular problems and insomnia.

Some strains of anthrax could be resistant to the vaccine. Someone with the proper knowledge and materials could try to culture such a strain. Vaccine- and antibiotic-resistant anthrax was one of the weapons being developed in the former
Soviet Union. Still, there is little or no reason to believe that this particular material ever made it out of the laboratory.

No. Only those persons determined by health officials to be at risk of exposure should take antibiotics. Taking antibiotics unnecessarily can be dangerous. The course of antibiotic treatment to prevent anthrax infection is long (60 days), and many people experience side effects.

Although most side effects are mild, severe ones may occur, such as diarrhea, abdominal symptoms, rash, and allergic reactions, and the use of antibiotics may dangerously interfere with other medications. In addition, the inappropriate use of antibiotics may cause the development of antibiotic-resistant strains of common bacteria.

No, storing a supply of antibiotics "just in case" can be dangerous. Antibiotics should only be taken under the supervision of a physician who has done an evaluation to minimize the potential for side effects or interaction with other medications.

Experts say it remains very difficult to transform the deadly bacterium into a weapon that can be effectively dispersed and kill large numbers of people. To develop an anthrax strain in its most lethal form — pulmonary anthrax — spores have to be crafted to just the right size. If too small, a person will exhale the spores. If too large, the spores fall to the ground and become ineffective.

A bomb carrying anthrax would likely destroy the germ as it explodes. Dispersing the bacterium with aerosols is challenging because, unless it is in spore form, it is a wet substance and can clog sprayers. The Aum Shinrikyo cult, which released the nerve gas sarin in the Tokyo subway system in 1995, killing 12 people, repeatedly tried to produce and disseminate anthrax, but failed to hurt anyone each time, according to testimony of its members.

Rapid detection of a disease outbreak remains a problem since many doctors have not been trained in how to recognize early symptoms of anthrax infection, though they have become much more alert in light of recent events. Emergency room doctors were quick to identify anthrax in the Florida cases.

There is new technology available that can help with detection. A portable DNA analyzer is available to quickly identify specific biological agents once an attack is suspected. Lawrence Livermore National Labs has invented a machine that tests air quality every half-hour and can sound an alarm if any of several pre-programmed biological or chemical agents are detected.

The machines can be installed at possible terrorist targets, including airports, subway stations, and government buildings.

Once detected, Anthrax is a relatively easy germ to handle, given that it is usually responsive to early antibiotics and is not contagious.