Last Updated

16 Dec 2002

Source: Washington Post, December 12, 2001.

Anthrax peril was likely high in Senate

DECATUR, Ga. - People in the Senate office where a letter containing anthrax spores was opened in October may have been exposed to concentrations of the bacteria that were tens, and possibly hundreds, of times higher than the normally fatal dose.

If that's the case, then immediate antibiotic treatment probably saved their lives and will be imperative for other targets of mail-borne anthrax attacks.

Those are among the conclusions suggested by experiments done by Canadian military researchers months before the events in the office of Senate Majority Leader Tom Daschle, D-S.D.

"There was a very great risk of someone getting massive concentrations of spores from just opening a letter," said Bill Kournikakis, a scientist at a laboratory in Alberta, who described his findings to about 100 epidemiologists, toxicologists, physicians and veterinarians meeting in Decatur to plan bioterror research.

The new study suggests doses of anthrax bacteria able to kill almost anyone are released in a Daschle-letter scenario.

Because the study was classified by the Canadian government, the findings were initially kept secret.

The findings were sent to a laboratory manager at the U.S. Centers for Disease Control and Prevention in Atlanta after the first anthrax case was reported in Florida. However, they apparently weren't reviewed until another CDC employee learned of the findings through other channels three weeks later.

The Canadians' research was done in response to an anthrax hoax in January, in which a powder-filled letter was sent to an immigration official in Ottawa.

He and his colleagues put 1 gram of powdered Bacillus globigii, a close relative of the anthrax bacterium, into an envelope. The particles were between 3 and 10 microns in diameter, small enough to be easily inhaled. The researchers then counted airborne spores for 10 minutes following the opening of a letter.

The researchers translated their findings into "LD-50s," which is the dose of spores that will kill 50 percent of people in a population. That dose is believed to be between 2,500 and 55,000 spores.

The researchers found that a person in the room where the envelope was opened could have received between 140 and 3,080 LD-50s of spores (depending on whether the low or high-end estimate of spores in an LD-50 is used). A letter containing 0.1 gram is not much safer. It released 22 to 480 LD-50s.

In both cases, the amount of powder wasn't enough to make the envelope feel lumpy or suspicious, Kournikakis said. Furthermore, most of it remained in the envelope even once the simulated letter was removed, dispersing the spores.

It's possible to survive a dose of anthrax bacteria that is multiple LD-50s, or to succumb to a fraction of a dose, as investigators suspect happened in the case of a 94-year-old woman who died of inhalation anthrax in Connecticut last month.

Numerous ideas for urgent research emerged from this two-day meeting, which ended Tuesday. Among the highest priorities are studies on how easily finely ground spores are passed from object to object in indoor environments, or are kicked back into the air once they've settled on a surface.

Another is whether giving an anthrax-exposed person anthrax vaccine along with antibiotics might make it possible to shorten the current 60-day course of medication.

A third is the need to determine whether antibodies filtered from the roughly 500,000 people who've gotten the vaccine could act as an antitoxin that would protect someone exposed to spores, or becoming ill with anthrax.

A fourth is the need to develop methods for rapidly evaluating powders, measuring the size and electric charge of particles, and identifying additives, that would allow investigators to immediately rate a substance's hazardousness.