No Need for Panic Over Anthrax, Officials Say

It’s hard to catch anthrax. Even when people are exposed to the bacterium, conditions must be just right for infection to take hold.

In part because of that, public health officials say people have little reason to worry that they will catch the infection, despite the current investigation in Florida of two cases of anthrax exposure.

“Right now, with two cases, I wouldn’t be pushing the panic button,” said Raymond Zilinskas, a senior scientist at the Monterey Institute of International Studies.

Doctors say more than 2,500 anthrax spores must be inhaled to actually cause the illness. The second case in Florida turned up when doctors did a test swab on a man in his 70s who was hospitalized for pneumonia and found anthrax spores in his nose. That man, Ernesto Blanco, does not have the disease, officials say.

Exposing large numbers of people to enough spores to cause illness would be difficult, experts say. It is relatively easy to find anthrax bacteria in infected animals and grow them in a laboratory. But anthrax is not contagious; individuals must be exposed to the bacteria firsthand to be infected. Sickening large numbers of people would require spraying the bacteria into the air in a carefully controlled manner--technically difficult, experts say.

The bacteria, Bacillus anthracis, can enter the body in three ways: through the skin, by inhalation or by eating food contaminated with it. How the disease is contracted matters greatly: If the bacillus is inhaled, death occurs in 90% of cases. The death rate is much lower when the bacteria enter the body through the gut or the skin. About 20% of untreated cases stemming from skin infection result in death.

Once in the body, the bacteria grow out of control, sending their host into shock. The bacteria also release a deadly toxin that kills key immune cells, leaving the body more vulnerable to infection. When those immune system cells, called macrophages, die, they spill further toxins into the bloodstream.

When not in the body, however, the bacillus goes into a dormant stage--the spore. In that form, it can lurk in the environment for years. Spores dropped on the Scottish island of Gruinard in Allied tests during World War II were still alive 40 years later, requiring the island to be decontaminated with formaldehyde.

For that reason, the bodies of animals that have died of anthrax must be burned, not buried, lest their graves become storage grounds for later infections.

Exposure to infected animals or to their products in the workplace is the most common way that anthrax infects people. Worldwide, about 2,000 people contract anthrax annually through the skin, most typically when handling contaminated wool, hides or leather.

In the United States, only 224 such cases were reported from 1944 to 1994, according to a May 1999 article in the Journal of the American Medical Assn. Only 18 cases of inhaled anthrax were reported in the country from 1900 and 1978. Most were among tannery workers and wool sorters at industrial mills. Before this month, the last known human death caused by anthrax in the United States was reported in 1976.

Some experts believe, however, that anthrax deaths may have been classified as unexplained because autopsies were not done and doctors did not identify symptoms.

Symptoms generally appear within seven days of exposure, although the time lapse between exposure and illness varies depending on how the disease is contracted. The first symptoms of disease are similar to a common cold or flu, but later stages include serious breathing problems and shock.

Because the flu season begins in the next few weeks, some public health officials are worried that people may panic and confuse flu symptoms with anthrax infection.

Antibiotics can prevent infection among people exposed to anthrax. But once symptoms appear, chances of survival drop markedly. In case of an anthrax outbreak, health officials would draw on a government stockpile of antibiotics.

But people should not take antibiotics as a preventive measure, said Dr. Jonathan Fielding, director of public health for Los Angeles County, because the danger from indiscriminate use of antibiotics is higher than the remote chances of being infected with anthrax.

For the same reasons, public health officials do not recommend immunizing the general public against the disease. Mass vaccination would be costly, potentially risky and would require far more doses of vaccine than exist.

The Defense Department originally wanted to vaccinate all 2.4 million U.S. active and reserve troops against anthrax because of the threat of its use in overseas biological warfare, but the military has scaled back its plans.

The U.S. and Russia experimented with anthrax as part of their biological weapons programs in the second half of the 20th century. By 1995, about 17 countries were believed to have such programs, although there is no firm evidence of anthrax being part of those, the Center for Civilian Biodefense Studies at Johns Hopkins University said.