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Last Updated

13 Dec 2002

Source: Washington Post, January 29, 2002.

One Anthrax Answer: Ames Strain Not From Iowa

By Joby Warrick, Washington Post Staff Writer

In four months, FBI agents and scientists have unraveled many of the mysteries surrounding the strain of anthrax used in last fall's deadly attacks. The "Ames strain" is now known to be highly virulent, resistant to many vaccines and a perennial favorite of military researchers and bioterrorists.

But here's one thing the lethal bug is decidedly not: originally from Ames, Iowa.

New details emerging from the infamous bacterium's murky past suggest the Ames strain did not come from the sleepy Iowa college town of the same name, or from anywhere else in Iowa. It was a Texas strain, cultured from a Texas cow, federal officials now say.

How it came to be known internationally as the Ames strain is a story of confused labeling and mistaken identity in the Defense Department's two-decade-old quest to find the perfect vaccine to protect troops against a near-perfect killer.

"It's been a puzzle," said the U.S. Department of Agriculture's Tom Bunn, one of several officials of the agency's Animal and Plant Health Inspection Service who have been trying to sort out the strain's true origins since it was first linked to the spate of bioterrorism attacks in Florida, New York and Washington.

The Ames strain -- one of 89 known genetic varieties of anthrax -- was used in each of the attacks on U.S. Senate offices and Florida and New York media companies in September and October. To law enforcement officials, that suggests the attacker had a scientific background and, quite possibly, access to one of a small group of U.S. military research labs and contractors known to possess Ames.

The Army acquired the strain in 1981 as part of a national search for novel types of anthrax to use in testing vaccines. It had no name until 1985, when it was described in a scientific paper by researchers at the U.S. Army Medical Research Institute of Infectious Diseases in Fort Detrick, Md.

The name "Ames" was chosen because the researchers believed the strain came from there: The shipping package bore a return address from the USDA's National Veterinary Services Laboratories, an Ames, Iowa, lab that diagnoses illnesses in cattle, according to Gregory Knudson, a former USAMRIID scientist and a co-author of the article that identified the strain. The label stuck.

But in the weeks after the anthrax attacks, questions emerged about the strain's origins. The Washington Post filed a request with the USDA under the Freedom of Information Act asking for details about the strain's history. After an exhaustive search, USDA officials in Iowa could find literally nothing: no record of anthrax strains delivered to the Army, and no reports of anthrax outbreaks among Iowa cattle in the early 1980s.

"When we went back and checked, there was no record of a bacterial culture coming from a cow in Iowa in 1980-81," said Bunn, chief of the USDA's Diagnostic Bacteriology Laboratory. He added: "If the Army asked for something we would have given it to them."

A search of long-forgotten Army documents finally resolved the mystery. The strain, it turns out, had come from Texas, which did experience anthrax outbreaks around 1980. The bacteria was isolated by the Texas Veterinary Medical Diagnostics Laboratory at Texas A&M University and shipped to USAMRIID in May 1981.

The germs were mailed in a special container, a package identical to hundreds of others that the USDA supplies to veterinary labs around the country. The return address on the package: The USDA's Veterinary Services Center, Ames, Iowa.