The Centers for Disease Control and Prevention says 5,000 people are now taking 60-day courses of the pills, chiefly Cipro and doxycycline, as a precaution against their potential exposure to anthrax spores. Many of the rest of the 32,000 who got the precautionary drugs have stopped, or will stop, taking the medications when tests show that their risk of exposure is minimal, the agency adds.
At last count, anthrax has been confirmed or suspected in 22 people, four of whom have died. Twelve of those cases involve the skin form of the infection, while 10 -- including the four deaths -- involve the much more lethal inhaled form.
In a report released today, the CDC says 1,132 employees of American Media Inc. in Boca Raton, Fla., began taking Cipro and other antibiotics last month after their potential exposure to the bioterrror bacteria. A photo editor at the media company was the first person to die from inhalation anthrax once the anthrax-by-mail attacks began.
A survey of 490 of those workers who took the anti-anthrax antibiotics showed that almost one in five reported having at least one bad reaction to the drugs, including itchiness, swelling, and breathing problems.
And six from a more narrow group of 95 surveyed stopped using the drugs and sought medical attention, including two who were treated in the emergency room and two who had to be hospitalized. However, the agency says none of those problems was linked to the drugs.
Dr. Jean Malecki, director of the Palm Beach County Health Department and lead author of the survey in the Nov. 9 Morbidity and Mortality Weekly Report, says officials had "a lot of anecdotal information, people saying 'I had this, I had that.'" But there was no solid evidence of adverse reactions to the drugs, she adds, and the 19 percent figure for minor episodes was expected.
Florida health workers continue to monitor people there who are still taking the antibiotics, and have set up a toll-free phone line for them to call with complaints. "We're following them very closely," Malecki says.
Health officials say they're now watching for potential drug reactions in New York, Washington, D.C., and New Jersey, where the majority of those taking preventive courses of antibiotics are. They include thousands of postal workers.
Dr. Stuart Levy, a Tufts University molecular biologist and president of the Alliance for the Prudent Use of Antibiotics, says he's not surprised that "with thousands of people on a drug that some are going to have side effects."
Their risk of adverse reactions is almost certainly far greater than the risk of contracting anthrax, and some of these problems may be serious, experts say. Bayer A.G.'s Cipro, for example, can trigger seizures in rare cases, and has been linked to other reactions including dizziness, confusion, depression and ruptured tendons, according to the Food and Drug Administration.
What's more, Levy adds, doctors have no idea what the effects of taking the drug for two months may be, because the typical prescription is for a few weeks at the most.
Dr. Calvin Kunin, a noted internist at Ohio State University in Columbus and an advisor to the antibiotics group, says the addition of 32,000 people to the million or so people who take the same antibiotics each day for other reasons isn't particularly significant. But it's likely to make a dent in the drugs' ability to kill germs.
"Every time that any drug is used, each occasion is a potential for pressure" on bacteria that can lead to resistance, he says.
"This is just the beginning of the number of people who will be taking Cipro" and other germ killers, he adds, "so we can anticipate selective pressure."
In a separate but related report, CDC officials issued guidelines for doctors to help them accurately diagnose lung anthrax and avoid confusing the disease with flu-like illnesses that have similar symptoms.
A review of the 10 confirmed and suspected inhaled anthrax cases so far shows that form of the disease almost never causes a runny nose, which is common in flu and similar infection, according to the CDC. Inhaled anthrax is also somewhat less likely than flu or flu-like infections to cause sore throats, headaches and diffuse muscle pain.
At the same time, patients with anthrax are more likely than flu sufferers to feel short of breath and have nausea and vomiting.
But Kunin says this kind of breakdown might be too finely parsed, particularly with a disease as rare as anthrax. For instance, one of the 10 people diagnosed with lung anthrax did have a runny nose. On the other hand, the report says that one in five people who have the flu does not have a runny nose.
"Why can't a person have a cold and anthrax at the same time?" Kunin asks, noting that the respiratory disease season is now heating up.
What To Do
For more on adverse reactions to medication, try the American Academy of Allergy, Asthma and Immunology.
The U.S. Food and Drug Administration has a warning to consumers about bogus offers to treat bioterror diseases. And the Alliance for the Prudent Use of Antibiotics has more on how to avoid drug-resistant germs, as well as the risks of stockpiling antibiotics to deal with bioterror threats.