What Is Anthrax?

Anthrax is a serious disease caused by Bacillus anthracis, a bacterium that forms spores. A bacterium is a very small organism made up of one cell. Many bacteria can cause disease. A spore is a cell that is dormant (asleep) but may come to life with the right conditions.

There are three types of anthrax:

    * skin (cutaneous)

    * lungs (inhalation)

    * digestive (gastrointestinal)

What are the types of anthrax infection?

Anthrax infection can occur in three forms: cutaneous (skin), inhalation, and gastrointestinal.

Cutaneous anthrax: Most (about 95%) 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 resembles an insect bite but within 1-2 days develops into a vesicle and then a painless ulcer, usually 1-3 cm in diameter, with a characteristic black necrotic (dying) area in the center. Lymph glands in the adjacent area may swell. About 20% of untreated cases of cutaneous anthrax will result in death. Deaths are rare with appropriate antimicrobial therapy.

Inhalation anthrax: Initial symptoms may resemble a common cold – sore throat, mild fever, muscle aches and malaise. After several days, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax is usually fatal.

Gastrointestinal anthrax: 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% to 60% of cases.

Where is anthrax usually found?

    Anthrax can be found globally. 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 others.

Can the presence of Bacillus anthracis spores be detected by a characteristic appearance, odor, or taste?

Bacillus anthracis spores do not have a characteristic appearance (e.g., color), smell, or taste. Spores themselves are too small to be seen by the naked eye, but have been mixed with powder to transport them.

How is anthrax transmitted?

Anthrax is not known to spread from one person to another person. B. anthracis spores can live in the soil for many years, and humans can become infected with anthrax by handling products from infected animals or by inhaling anthrax spores from contaminated animal products. Anthrax can also be spread by eating undercooked meat from infected animals. It is rare to find infected animals in the United States. Anthrax spores can be used as a bioterrorist weapon, as was the case in 2001, when Bacillus anthracis spores had been intentionally distributed through the postal system, causing 22 cases of anthrax, including 5 deaths.

Can anthrax be spread from person-to-person?

    Person-to-person transmission is extremely unlikely and has only reported with cutaneous anthrax, where discharges from skin lesions are potentially infectious.   Communicability is not a concern in managing or visiting with patients with inhalation anthrax.

How common is anthrax and who can get it?

    Anthrax is most common in agricultural regions where it occurs in animals. These include South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean, and the Middle East. When anthrax affects humans, it is usually due to an occupational exposure to infected animals or their products. Workers who are exposed to dead animals and animal products from other countries where anthrax is more common may become infected with B. anthracis (industrial anthrax). Anthrax outbreaks occur in the United States on an annual basis in livestock and wild game animals such as deer.

How Do You Get It?

Anthrax is not known to spread from one person to another.

Anthrax from animals. Humans can become infected with anthrax by handling products from infected animals or by breathing in anthrax spores from infected animal products (like wool, for example). People also can become infected with gastrointestinal anthrax by eating undercooked meat from infected animals.

Anthrax as a weapon. Anthrax also can be used as a weapon. This happened in the United States in 2001. Anthrax was deliberately spread through the postal system by sending letters with powder containing anthrax. This caused 22 cases of anthrax infection.

How Dangerous Is Anthrax?

The Centers for Disease Control and Prevention classifies agents with recognized bioterrorism potential into three priority areas (A, B and C). Anthrax is classified as a Category A agent. Category A agents are those that:

    * pose the greatest possible threat for a bad effect on public health

    * may spread across a large area or need public awareness

    * need a great deal of planning to protect the public’s health

In most cases, early treatment with antibiotics can cure cutaneous anthrax. Even if untreated, 80 percent of people who become infected with cutaneous anthrax do not die. Gastrointestinal anthrax is more serious because between one-fourth and more than half of cases lead to death. Inhalation anthrax is much more severe. In 2001, about half of the cases of inhalation anthrax ended in death.

What are the case fatality rates for the various forms of anthrax?

Early treatment of cutaneous anthrax is usually curative, and early treatment of all forms is important for recovery. Patients with cutaneous anthrax have reported case fatality rates of 20% without antibiotic treatment and less than 1% with it. Although case-fatality estimates for inhalation anthrax are based on incomplete information, the rate is extremely high, approximately 75%, even with all possible supportive care including appropriate antibiotics. Estimates of the impact of the delay in postexposure prophylaxis or treatment on survival are not known. For gastrointestinal anthrax, the case-fatality rate is estimated to be 25%-60% and the effect of early antibiotic treatment on that case-fatality rate is not defined.

What Are the Symptoms of Anthrax?

These symptoms can occur within 7 days of infection:

    * Fever (temperature greater than 100 degrees F). The fever may be accompanied by chills or night sweats.

    * Flu-like symptoms

    * Cough, usually a non-productive cough, chest discomfort, shortness of breath, fatigue, muscle aches

    * Sore throat, followed by difficulty swallowing, enlarged lymph nodes, headache, nausea, loss of appetite, abdominal distress, vomiting, or diarrhea

    * A sore, especially on your face, arms or hands, that starts as a raised bump and develops into a painless ulcer with a black area in the center.

See also Notice to Readers: Considerations for Distinguishing Influenza-Like Illness from Inhalational Anthrax.

Symptoms of disease vary depending on how the disease was contracted, but symptoms usually occur within 7 days.

    Cutaneous: Most (about 95%) anthrax infections occur when the bacterial spore 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 resembles an insect bite but within 1-2 days develops into a vesicle and then a painless ulcer, usually 1-3 cm in diameter, with a characteristic black necrotic (dying) area in the center. Edema or swelling of the surrounding tissues may develop and lymph glands in the adjacent area may swell. About 20% of untreated cases of cutaneous anthrax will result in death. Deaths are rare with appropriate antimicrobial 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, and even with aggressive antibiotic and supportive therapy 45% of inhalation anthrax cases were fatal in the bioterrorist attack in the fall of 2001.

    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 include nausea, loss of appetite, vomiting, fever are followed by abdominal pain, vomiting of blood, and severe diarrhea. Symptoms may also include lesions and soreness in the throat, difficulty swallowing, marked swelling of the neck and regional lymph glands. Intestinal anthrax results in death in 25% to 60% of cases.

How Soon Do Infected People Get Sick?

Symptoms can appear within 7 days of coming in contact with the bacterium for all three types of anthrax. For inhalation anthrax, symptoms can appear within a week or can take up to 42 days to appear.

How is anthrax diagnosed?

    Anthrax is diagnosed by culture and isolation of the causative bacterium, B. anthracis; by detecting the bacterial DNA or antigens; or by measuring specific antibodies in the blood of persons with suspected cases.   The bacteria can be cultured from the blood, skin lesions, fluid from the lungs or respiratory secretions, spinal fluid, or other affected tissues prior to the start of antibiotic treatment.    Detection of the DNA or antigens of the bacteria, and detection of antibodies in the blood of suspected cases, are important tools for diagnosis because positive culture is unlikely after antibiotic treatment has been started.

How Is Anthrax Treated?

Antibiotics are used to treat all three types of anthrax. Early identification and treatment are important. If left untreated, the disease can be fatal.

Prevention after exposure. Treatment is different for a person who is exposed to anthrax, but is not yet sick. Health-care providers will use antibiotics (such as ciprofloxacin, levofloxacin, doxycycline, or penicillin) combined with the anthrax vaccine to prevent anthrax infection.

Treatment after infection. Treatment is usually a 60-day course of antibiotics. Success depends on the type of anthrax and how soon treatment begins.

Ciprofloxacin, doxycycline and penicillin are FDA-approved for the treatment of anthrax in adults and children.

Can Anthrax Be Prevented?

Vaccination. There is a vaccine to prevent anthrax, but it is not yet available for the general public. Anyone who may be exposed to anthrax, including certain members of the U.S. armed forces, laboratory workers, and workers who may enter or re-enter contaminated areas, may get the vaccine. Also, in the event of an attack using anthrax as a weapon, people exposed would get the vaccine.

In countries where anthrax is common and vaccination levels of animal herds are low, humans should avoid contact with livestock and animal products and avoid eating meat that has not been properly slaughtered and cooked. Also, an anthrax vaccine has been licensed for use in humans. The vaccine is reported to be 93% effective in protecting against anthrax.

What Should I Do if I Think I Have Anthrax?

If you are showing symptoms of anthrax infection, call your health-care provider right away.