For decades, microbiologists have exchanged anthrax strains for research with few restrictions, even the most virulent isolates. Unless its a rare strain, Spertzel says the spores used in the attacks could have come from anywhere.
The "Ames" strain has been the focus of much speculation in the press, as law enforcement sources say it was the source of the Florida exposures. But it isn't that rare. The strain was extracted from a dead cow in Ames, Iowa, in the 1950s, then sent to the U.S. Army Medical Research Institute of Infectious Diseases around 1980 for research.
British and American scientists discovered that Ames was one of the strains that defeated the licensed U.S. and British anthrax vaccines. Quite simply, it killed vaccinated guinea pigs. (Before you get too scared, antibiotics successfully kill the Ames strain). One can find Ames "reference strains" in laboratories around the world.
But if the agents used in the attack are found to contain the telltale presence of certain compounds used in a professional drying process, this could be a very revealing clue. For instance, the presence of aluminum clay, an anti-clumping agent employed in an air-drying process for anthrax, would point to professionals rather than amateurs, and narrow the field of possible suppliers.
It's clear the Florida cases involved a less elegant preparation with spores of an inconsistent size. Still, someone succeeded in manufacturing tens of thousands of particles, or more, to the required size to infect two victims with pulmonary anthrax. That took more than a mortar and pestle.