HEALTH MATTERS
By: David Herman, M.D.
You can no longer pick up a newspaper or listen to a news broadcast without hearing the term anthrax. Just what is anthrax?
Anthrax is an infectious disease caused by the bacterium Bacillus anthracis. It occurs most frequently as a disease of herbivores (e.g., cattle, goats or sheep) that acquire spores after direct contact with contaminated soil. Humans usually become infected through direct contact with B. anthracis spores from infected animals or their products (e.g., goat hair).
Anthrax can take one of three clinical forms.
Cutaneous anthrax, the most common form, occurs when an open wound is exposed to the spores. As of Oct. 25, despite many possible exposures in New York, New Jersey and Washington, D.C., CNN reported that there are only seven documented cases of cutaneous anthrax. The incubation period ranges from 1-12 days. A skin lesion called a papule (raised, itchy bump) forms, and over a period of several days evolves to form an eschar (blackened ulcer). This blackened ulcer is where anthrax, which is the Greek word for coal, gets its name. If treated, cutaneous anthrax has a mortality rate below 1 percent. Over a 50-year period, from 1944-1994, only 224 cases of cutaneous anthrax were reported in the United States.
Gastrointestinal anthrax is extremely rare and develops as a result of ingesting insufficiently cooked contaminated meat. It has an incubation period of 1-7 days. Watery diarrhea, gastrointestinal bleeding and abdominal pains are the symptoms. The mortality rate is high, in large part because it is difficult to diagnose.
Inhalational anthrax, the most lethal form of the disease, occurs by breathing in at least 8,000-50,000 anthrax spores. The incubation period ranges from 1-7 days and may extend to 60 days. Symptoms develop in two stages. The first stage involves non-specific symptoms that include fever, headache, cough, chills, difficulty breathing, abdominal pain, chest pain, malaise and vomiting. The symptoms then resolve briefly before the onset of the second stage that includes the sudden onset of fever, profuse sweating, respiratory failure, shock and possible death.
The diagnosis of anthrax involves isolating the bacteria from the blood, skin lesions or spinal fluid. Antibody tests are generally not useful for identification of illness. If a patient is infected with anthrax, antibiotics are prescribed.
People are currently concerned about being tested for and taking antibiotics for possible exposure to anthrax to prevent illness. According to the New Jersey Department of Health and Senior Services, asymptomatic patients without known exposure to a confirmed culture-positive letter/package or environmental sample should not be tested for anthrax.
The likelihood of becoming ill with anthrax in an asymptomatic patient with no known exposure is remote. Testing such patients will only serve to overwhelm the medical system and result in preventing timely testing to patients for whom it is indicated. Asymptomatic patients with potential exposure to a confirmed culture-positive letter/package/environment should receive antibiotic prophylaxis as recommended by public health authorities.
It is important to remember that patients experiencing upper respiratory symptoms with no known exposure to anthrax do not have anthrax and need not be tested. Cold and flu season is upon us. Patients with cold and flu symptoms likely have a cold or the flu.
Although the antibiotic Cipro was approved by the FDA for treatment of inhalational anthrax based on a small study of monkeys by the Defense Department, other antibiotics have been shown to be effective against other forms of the disease.
Amoxicillin is the antibiotic of choice for sensitive strains. Doxycycline has also been shown to be effective. Other fluoroquinolone antibiotics such as Levaquin and Tequin are likely to be equally efficacious. Because of the concern of possible penicillin and doxycycline-resistant bio-engineered strains, fluoroquinolone antibiotics are recommended for empiric therapy after exposure to an unknown source until sensitivity tests are available.
For optimum effectiveness, early treatment is required. It should be noted that the recent strain of B. anthracis in Florida was sensitive to both amoxicillin and doxycycline.
During the 1950s, a human vaccine was developed in the United States to protect textile mill workers. The vaccine is indicated for military personnel who may come in contact with anthrax spores and for workers who come in contact with imported animal hides, furs, bone meat, wool, animal hair (especially goat hair) and bristles. Anthrax vaccine has been routinely given in the United States to active-duty military personnel since 1970. The vaccine has a 93 percent success rate in protecting against cutaneous anthrax, and there have been no reports of long-term illness related to vaccination. The vaccine is not available to civilians.
The risk of acquiring inhalational anthrax from a bioterrorist dissemination of the spores is extraordinarily low. In order to infect people, the spores must be processed by using very sophisticated technology so as to make them small enough and stable enough to be airborne and dispersible. Spores dropped from an airplane would be diluted in the atmosphere, rendering the chance of inhaling 8,000-50,000 of them improbable. Cutaneous anthrax will only occur to persons who come in direct contact with the spores. Neither form of anthrax is contagious from person to person.
People should not keep antibiotics at home for self-administration. In the unlikely event of an aerosolized dissemination of anthrax spores, the government maintains a stockpile of antibiotics large enough to treat two million people for 60 days. Plans are underway to increase this stockpile even further. The antibiotics would be rushed to any location in the United States within 12 hours of an attack.
If people stockpile antibiotics at home, medication may become unavailable to those who actually need it. Furthermore, people will be tempted by fear to take them unnecessarily, resulting in the formation of dangerous antibiotic-resistant bacteria. The danger of the creation of these resistant bacteria by unnecessary antibiotic use far outweighs any potential benefit of prophylactic antibiotic use in such low-risk situations. Many people will also suffer potentially serious side effects from taking unnecessary antibiotics.
If you receive a suspicious piece of mail or suspect that you have been exposed to anthrax, call 9-1-1 and await further instructions. For further information, you can log onto www.state.nj.us/health, www.bt.cdc.gov, and www.hopkins-biodefense.org.
Dr. David Herman is a board-certified infectious disease specialist on staff at The Medical Center at Princeton. This article was prepared in collaboration with Lorraine Seabrook.

