Bacteria took high level of skill to make

The anthrax spores delivered to a Senate office appear to be concentrated, pure and processed to a minute size that would make them a formidable weapon, government officials said Wednesday, suggesting that the biological attack required sophisticated expertise.

Evidence also mounted that the anthrax attacks in Washington, Florida and New York may have been coordinated. The federal Centers for Disease Control and Prevention said Wednesday that anthrax spores collected from Florida and New York belong to the same bacterial strain. Investigators earlier said similarities of letters and writing in the New York and Washington attacks indicated those cases also were linked.

Sen. Bill Frist, R-Tenn., who was briefed by investigators at the U.S. military’s Ft. Detrick, Md., testing laboratory, said the spores that contaminated congressional workers were mostly a uniform size of 1 to 3 microns -- about one-tenth the width of a human hair. Experts said that particle size is ideal for infecting people with dangerous inhalation anthrax, and it would take significant technical skill to produce.

Throughout the day Wednesday, reports varied as to the quality of the anthrax spores; officials backed away from earlier reports that the Washington spores were “weapons grade.” Yet statements by health officials that the anthrax was of high quality suggest it could have originated in the biological weapons program of a foreign state, some experts said. At the least, experts said, the evidence points to a group with extensive resources.

“It certainly tells me that it’s more sophisticated than just some prankster growing the organism and sending it,” said Ronald Atlas, president-elect of the American Society for Microbiology.

Maj. Gen. John Parker, commander of medical research at Ft. Detrick, said at a Washington news conference Wednesday that the anthrax found in Sen. Tom Daschle’s office was a “common variety” that is sensitive to all antibiotics, including penicillin and ciprofloxacin.

“I can say that the sample is pure spores,” said Parker, who had examined the sample with an electron microscope.

Parker said the strain of the Washington sample has not been established. Investigators have said the Florida anthrax belongs to the Ames strain, a virulent but natural form of the bacteria often used in labs to test the effectiveness of anthrax vaccines.

Frist, a former transplant surgeon, said the fact that the Washington anthrax was not modified to be resistant to antibiotics suggests that the spores might not have been produced in a foreign nation’s weapons labs.

Yet other experts said that if the reports of uniform particle size are accurate, that suggests the perpetrators had some familiarity with state-sponsored bioweapons research, such as that performed in Iraq and the former Soviet Union.

It would be exceptionally difficult for even a skilled researcher to make spore particles of uniform size, said Gary Ackerman, a microbiologist and research associate with the Monterey Institute of International Studies.

“If you grind down anthrax in something like an average coffee grinder, you’ll destroy many of the spores,” Ackerman said. “You’ll also end up with all different particle sizes. If you really want to get the maximum bang for the buck, you have to engineer it to get a uniform spore size and to kill as few spores as possible. That requires quite a bit more technical sophistication.”

Scott Lillibridge, a bioterrorism expert at the U.S. Department of Health and Human Services, said during congressional testimony Wednesday that the Washington anthrax had been extensively processed.

“There’s been some attempt to collect it, perhaps refine it and perhaps make it more concentrated,” Lillibridge said.

Another possible clue, experts said, is that 31 staffers were exposed from what appears to have been a single envelope. That could indicate that the anthrax was in a dry powder form that floats easily in the air -- another challenging technical hurdle.

Producing anthrax spores that can travel in the air and contaminate many people probably would require tailor-made industrial equipment for freeze-drying and milling the spores to a minute size, experts said. Drying them makes them lighter and less likely to clump and fall.

“To make a dry, dustlike agent is a difficult technical feat,” said Raymond Zilinskas, a Monterey Institute scientist who inspected biological weapons plants in Iraq for the United Nations Special Commission.

It took the U.S. and the former Soviet Union decades and hundreds of millions of dollars to perfect the process of drying spores and milling them down to a usable size, experts said.

“The Iraqis had a dryer, so they were experimenting, but they hadn’t come up with an effective form of the dry agent,” Zilinskas said.

The resources necessary to make such sophisticated spores would be almost impossible for an individual to marshal and probably would be available only to someone who had contact with a state-run program, said Mike Powers, a research associate with the Washington-based Chemical and Biological Arms Control Institute.

Atlas of the Society for Microbiology agreed that the preparation took sophistication, though he said an independent group might have made high-quality anthrax on a small scale, without the help of a state.

Another challenge of making such agents is to avoid getting infected, said Mary Gilchrist, a University of Iowa microbiologist who helped form the CDC’s nationwide bioterrorism detection network. Such prevention could take “some pretty exotic safety devices,” Gilchrist said.

The sort of knowledge necessary to make such spores might have come from technicians who once worked in a state bioweapons program, said Ackerman of the Monterey Institute. It’s also possible that the spores were stolen from a foreign weapons lab or intentionally supplied to the attackers by a rogue state.

In a report to the Senate in 1995, the Office of Technology Assessment identified 17 countries believed to possess biological weapons: Libya, North Korea, South Korea, Iraq, Taiwan, Syria, Israel, Iran, China, Egypt, Vietnam, Laos, Cuba, Bulgaria, India, South Africa and Russia.

Chicago Tribune staff reporters Peter Gorner, Ronald Kotulak and Michael Dorning contributed to this report.