WASHINGTON (AP)--A U.S. Department Agriculture official left June 16 for England carrying brain tissue samples from a cow suspected of having bovine spongiform encephalopathy.

The cow was declared free of the infection seven months ago, but the department did further tests in mid-June that came back positive.

The samples are destined for the internationally recognized laboratory in Weybridge, England, that gave independent confirmation of the first U.S. case of BSE in December 2003.

"When we have all of the final results, we will share them very publicly," Secretary of Agriculture Mike Johanns said in a statement June 16. The department has said testing will take about a week.

The lab will perform a combination of tests already done in the U.S., said Dr. John Clifford, the department's chief veterinary officer. More analysis will also be done at the National Veterinary Services Laboratory in Ames, Iowa, he said.

When it announced the suspected case on June 10, the department raised the possibility that it might be a different, naturally occurring strain of the disease.

Some experts have theorized that "atypical" strains can happen spontaneously and not result from eating infected cattle remains, which is the only way the disease is known to spread in cattle.

"There is such a thing in Europe that is called 'atypical BSE,' about which there's a lot of information and data that is still needed out there," Clifford said.

A scientist who works on the issue said that theory has limitations.

"If this phenomenon occurs, then why haven't we seen it before?" said Robert Rohwer, an expert on the disease who is affiliated with the University of Maryland. "We have the largest cattle population in the world and have had for decades. Why now?"

Rohwer said the theory could be used to help deflect concern about the suspected case because an animal that spontaneously developed the disease would not have caught it from another infected cow.

But he said it would be difficult to prove this case is atypical with the limited tissue samples remaining. The department has 12 grams of tissue from obex, which is part of the brain stem, and 30 grams from cerebellum, which lies just above the brain stem.

While lesions from BSE tend to be found in the brainstem, atypical cases may develop lesions in other parts of the brain, he said.

People who eat contaminated meat can develop a fatal brain disorder called variant Creutzfeldt-Jakob disease. The cow in question was a "downer," unable to walk, which is banned from the food supply.

Date: 6/23/05

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