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Anthrax is an acute infectious disease caused by the spore-forming bacterium bacillus anthracis. Anthrax most commonly occurs in wild and domestic lower vertebrates (cattle, sheep, goats, camels, antelopes, and other herbivores), but it can also occur in humans when they are exposed to infected animals or tissue from infected animals.
Because anthrax is considered to be a potential agent for use in biological warfare, the Department of Defense has begun mandatory vaccination of all active duty military personnel who might be involved in conflict.
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 in wild livestock has occurred in the United States.
Anthrax infection can occur in three forms: cutaneous (skin), inhalation, and gastrointestinal. 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.
Symptoms of disease vary depending on how the disease was contracted, but symptoms usually occur within seven days.
• Cutaneous: 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: 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. Intest-
inal anthrax results in death in 25% to 60% of cases.
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.
Direct person-to-person spread of anthrax is extremely unlikely to occur. Communicability is not a concern in managing or visiting with patients with inhalational anthrax.
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.
The anthrax vaccine is manufactured and distributed by BioPort Corp. of Lansing, MI. The vaccine is a cell-free filtrate vaccine, meaning it contains no dead or live bacteria in the preparation. The final product contains no more than 2.4 mg of aluminum hydroxide as adjuvant. Anthrax vaccines intended for animals should not be used in humans.
The Advisory Committee on Immunization Practices recommends anthrax vaccination for:
Contact the anthrax Vaccine Immunization Program in the Army Surgeon General’s Office at (877) 438-8222. Web site: www.anthrax.osd.mil. Pregnant women should be vaccinated only if absolutely necessary.
The immunization consists of three subcutaneous injections given two weeks apart followed by three additional subcutaneous injections given at six, 12, and 18 months. Annual booster injections of the vaccine are recommended thereafter.
Mild local reactions occur in 30% of recipients and consist of slight tenderness and redness at the injection site. Severe local reactions are infrequent and consist of extensive swelling of the forearm in addition to the local reaction. Systemic reactions occur in fewer than 0.2% of recipients.
Anthrax is diagnosed by isolating B. anthracis from the blood, skin lesions, or respiratory secretions or by measuring specific antibodies in the blood of persons with suspected cases.
Doctors can prescribe effective antibiotics. To be effective, treatment should be initiated early. If left untreated, the disease can be fatal. Three types of antibiotics are approved for anthrax: ciprofloxacin, tetracyclines (including doxycycline), and penicillins. For people who have been exposed to anthrax but do not have symptoms, 60 days of one of these antibiotics is given to reduce the risk or progression of disease due to inhaled anthrax.
The Department of Defense recommends that servicemen and women contact their chain of command on questions about the vaccine and its distribution. The anthrax Vaccine Immunization Program in the U.S. Army Surgeon General’s Office can be reached at (877) 438-8222. Web site: www.anthrax.osd.mil
Source: National Center for Infectious Diseases, Atlanta, GA.