August 2, 2008

Inhaled Form of Anthrax More Deadly Than Skin Infection

Americans became fearful of anthrax in October of 2001, after the white powder killed five people and sickened 17 as it was sent in envelopes through the U.S. postal service. The deadly attacks created contamination scares throughout the country and forced the post office to alter its letter-handling procedures.

The tragedy is now back in the news with the apparent suicide of biodefense researcher Bruce E. Ivins of the government labs at Fort Detrick, Maryland. At the time of his death, prosecutors had been preparing to seek charges against Ivins for the 2001 attacks.

The spores that cause anthrax, Bacillus anthracis, commonly occur in soil. At one time, the skin form of the anthrax infection was fairly widespread, especially among livestock and those who work with the animals, and effectively treated with antibiotics.

However, the mailed anthrax proved deadly as the spores were inhaled when the poisoned mail was opened. These spores then settled in the lungs of those exposed, causing an infection that is difficult to diagnose and nearly impossible to cure once symptoms appear. The infection is not contagious.

Experts initially estimated that 8,000 to 10,000 spores in the lungs can cause the inhaled form of an anthrax infection, but later questioned the figure. Infection with the skin form of the disease can result from significantly fewer spores.

In the aftermath of the attacks, there were media reports that the contaminated letters contained additives and had also been subjected to sophisticated milling, techniques used to weaponize the anthrax spores to make them more deadly. However, officials with the FBI later said these reports were inaccurate.

The skin form of an anthrax infection typically begins three to five days after exposure, with the appearance of a small, painless blister that is red around the edges. A day or two later, the blister turns black before eventually drying up and leaving a black scab behind. The scab usually falls off within a week or two. Anthrax skin infections are treated with common antibiotics such as Cipro, penicillin or doxycycline, which are very effective. 

Experts say that left untreated, approximately 5 percent of anthrax skin infections will progress to a deadly bloodstream infection that is almost always fatal.

Additional information about anthrax can be viewed at the U.S. Centers for Disease Control and Prevention Web site at http://emergency.cdc.gov/agent/anthrax/needtoknow.asp.