Searching for a test

Canadian health authorities have but one grisly way to stop mad cow disease: Kill all 150 animals at the Alberta ranch where a single, unsteady old cow was stricken.

That is because no simple diagnostic test is available for bovine spongiform encephalopathy in live animals.

“We can’t look for the agent that causes mad cow disease itself,” said Dr. Stephen Sundlof, director of the Food and Drug Administration’s Center for Veterinary Medicine. “The science hasn’t gotten us that far.”

Dr. Sundlof and others say an early diagnostic test for BSE would save money, time and healthy livestock, and would stifle the public alarm that mad cow triggers.

In the past two years, several potential live tests using blood, urine and nasal mucous have generated biotech buzz and inflated stock prices, but skeptical researchers and regulators say it may be years before an experimental method proves reliable.

“I’ll believe it when I see the test,” said University of Wisconsin microbiologist Judd Aiken.

“These diseases have an extended preclinical stage where there are no symptoms, and yet the animal has high levels of the infectious agent,” Mr. Aiken said. “It is exceedingly important to develop a test that will identify the disease earlier and keep [other] animals alive.”

Mad cow disease appeared in Britain in 1986 and spread to countries in Europe and Asia. It is thought to have been carried in cattle feed that included protein and bone meal from sheep or other mammals infected with otherspongiform diseases.

The cattle disease is linked to a brain-destroying human illness called new variant Creutzfeldt-Jakob disease. The human illness is believed to be spread by eating brain or nerve tissue from infected animals and has killed at least 132 persons, 122 of them in Britain.

No BSE has been found in U.S. cattle. The FDA outlawed feeding meat and bone meal from mammals to cattle, sheep and goats in 1997, the same year Canada issued a similar ban.

Canadian officials say the infected cow there may have been born before that ban, but they are not certain about its age.

Test results have cleared all other cattle in the original herd linked to the mad cow case, Canadian officials announced yesterday.

“The results from diagnostic testing on the first quarantined herd are negative,” said Dr. Laude Lavigne of the Canadian Food Inspection Agency.

“It means the incidence of BSE in Canada presently remains in one cow.”

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