Definition of Anthrax
Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax most commonly occurs in warm-blooded animals, but can also infect humans.
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 (industrial anthrax) from other countries where anthrax is more common may become infected with B. anthracis. Anthrax in animals rarely occurs in the United States. Most reports of animal infection are received from Texas, Louisiana, Mississippi, Oklahoma and South Dakota.
Symptoms of disease vary depending on how the disease was contracted, but symptoms usually occur within seven days.
Cutaneous: Most 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: Initial symptoms may resemble a common cold. After several days, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax usually results in death in 1-2 days after onset of the acute symptoms.
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% to 60% of cases.
How is anthrax diagnosed?
Anthrax is diagnosed by isolating B. anthracis from the blood, skin lesions, or respiratory secretions or by measuring specific antibodies in the blood of suspected cases.
What is the treatment for anthrax?
Doctors can prescribe effective antibiotics. Usually penicillin is preferred, but erythromycin, tetracycline, or chloramphenicol can also be used. To be effective, treatment should be initiated early. If left untreated, the disease can be fatal.
Is there an anthrax vaccine for humans?
The anthrax vaccine for humans licensed for use in the United States is a cell-free filtrate vaccine, which means it uses dead bacteria as opposed to live bacteria. Anthrax vaccine is indicated for individuals who come in contact in the workplace with imported animal hides, furs, bonemeat, wool, animal hair (especially goat hair), and bristles; and for individuals engaged in diagnostic or investigational activities which may bring them into contact with anthrax spores. The vaccine is reported to be 93% effective in protecting against cutaneous anthrax. The anthrax vaccine was developed and is manufactured and distributed by the Michigan Biologic Products Institute, Lansing, Michigan. Anthrax vaccines intended for use in animals should not be used in humans.
Who should be vaccinated against anthrax?
Because anthrax is considered to be a potential agent for use in biological warfare, the Department of Defense recently announced that it will begin systematic vaccination of all U.S. military personnel. Among civilians, the Advisory Committee for Immunizations Practices (ACIP), recommends anthrax vaccine be given to individuals who come in contact in the workplace with imported animal hides, furs, bonemeat, wool, animal hair (especially goat hair), and bristles; and for individuals engaged in diagnostic or investigational activities which may bring them into contact with anthrax spores. The vaccine should only be administered to healthy men and women from 18 to 65 years of age since investigations to date have been conducted exclusively in that population. Because it is not known whether the anthrax vaccine can cause fetal harm, pregnant women should not be vaccinated.