Anthrax: Disease of the Past Becomes Terror of the Present
By Herman Rosen, M.D.

Until recently, anthrax was an uncommon disease in the United States. Prior to 2001, the last person to die of anthrax in the U.S. was a home weaver who inhaled anthrax spores introduced by infected Pakistani yarn in 1976. He died of a disease known as “woolsorters’ disease.” In the ‘80s and ‘90s only four American cases of cutaneous (skin) anthrax were reported. This enormous reduction in the number of cases in the U.S. was a result of restriction in the importation of infected wool and vaccination of textile workers exposed to raw fiber.

Anthrax is caused by a specific bacterium, Bacillus anthracis (called B. anthracis by microbiologists). Under the microscope the bacteria are gram-positive, rod-shaped and tend to form chains resembling boxcars. Pasteur worked with B. anthracis in order to produce the first vaccine against a bacterial disease, used to successfully immunize sheep against anthrax infection. The bacterium B. anthracis, when faced with a lack of food can transform into a dormant, spore state. These spores can remain in the soil for years, and are able to withstand harsh conditions. When a grazing animal eats grass or other plants from an area where spores are in the ground, the spores can be inhaled or eaten or contact the animal’s skin. The spores are carried to the animal’s lymph nodes where they transform into bacteria, multiply and infect the animal. Anthrax most often occurs in grazing animals such as sheep, goats, cattle, camels and antelopes. When the infected animals die, the bacteria return to the spore state.

Anthrax is seen in animals in South America, the Caribbean, Eastern Europe, Asia, Africa, and the Middle East. Humans can become infected when they come in contact with material from infected animals or by eating undercooked meat from infected animals.

How does anthrax affect humans? There are three major syndromes: cutaneous, inhalational and intestinal. Each syndrome has manifestations that are caused by three toxins produced by the bacteria. The toxin “edema factor” causes tissue swelling; “lethal factor” causes death when injected into animals. The third toxin, ostensibly misnamed “protective antigen” is necessary for the toxic action of edema factor and lethal factor.

Cutaneous anthrax accounts for 95% of the disease in man. It occurs when the bacillus enters a cut on the skin, such as can occur when handling contaminated hides, wool or fur of infected animals. The infection begins as an itchy bump resembling an insect bite. In 1-2 days a small blister forms which ulcerates and forms a painless black, necrotic scar. The black scar resembles anthracite coal, hence the name of the bacteria, B. anthracis. Lymph nodes around the scar enlarge. Appropriate antibiotic therapy will result in a cure. However, about 20% of untreated cutaneous anthrax cases will lead to death.

The most severe form of anthrax is inhalational. Airborne anthrax spores, which are a tiny 2-5 microns in diameter, pose the most serious threat since they can pass down the trachea and bronchi and lodge in the air sacs of the lung. Scavenger cells carry the spores behind the lung, to an area called the mediastinum where lymph nodes begin to swell. These swollen nodes can be seen on chest x-ray and are an important finding in making the diagnosis of inhalational anthrax. Initial symptoms such as weakness, fever, muscle aches and headaches resemble the flu. But after 2-3 days the patient with anthrax develops severe respiratory distress, blue lips and nails due to lack of oxygen and shock. At this time the organisms are multiplying and spread throughout the body. This form of anthrax, unless treated early, is often fatal.

The third form of anthrax is intestinal, which can occur following ingestion of contaminated meat. Initially there is nausea, vomiting, fever, abdominal pain, later vomiting of blood and severe diarrhea. Death occurs in approximately 50% of untreated cases.

The treatment of anthrax is with antibiotics. For cutaneous anthrax, penicillin administered intravenously is effective against most strains of the bacteria, and ciprofloxacin (Cipro®) administered intravenously or oral doxycycline is also effective. Avoid doxycycline in pregnant women.

Inhalational anthrax is treated with IV antibiotics, starting with Cipro. The Center for Disease Control has suggested that drugs like clindamycin and rifampin can be added to prevent anthrax from causing meningitis. As the patient improves, oral antibiotics can be substituted. Treatment has to continue for two months.

Anthrax is not contagious from a patient to another person. It is not spread by coughing or sneezing. Letters containing B. anthracis spores were sent to people in Washington and New York City. If a person has had documented exposure to sources of B. anthracis they should be offered antibiotics to prevent the disease. No controlled studies in humans have been done to validate current treatment recommendations. Cipro or doxycycline are recommended but amoxicillin may be used in individuals allergic to the other agents.

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