Is 'Mad Cow' in Sheep a No-Brainer?

Scientists in the United Kingdom were about to publish results indicating that sheep may harbor bovine spongiform encephalopathy (BSE), or "mad cow disease." That would raise the possible nightmare of humans contracting variant Creutzfeldt-Jakob disease (vCJD) from mad sheep as well as mad cows (Science, 17 March 2000, p. 1906). But last week the paper was suddenly pulled from the online edition of the Journal of General Virology when, in a final check, an independent lab discovered a possible case of mistaken identity. The "sheep brain" used in the study may actually have come from cattle.

The work was done by an Edinburgh-based team from the U.K.'s Institute for Animal Health (IAH). Chris Bostock, IAH's chief, says that early this year the government's Veterinary Laboratories Agency (VLA)--which IAH had asked to check the samples to insure they were not contaminated with cattle brains--had reassured him that they appeared to be 100% sheep. But after a second lab concluded last week that it was all cattle brain, the VLA told Bostock that its laboratory had analyzed the wrong samples and withdrew its original reassurance that they were pure sheep. The IAH is now conducting an internal audit to determine whether it really did misidentify the samples and, if so, establish what the material actually was.

The episode has tattered the public reputation of the IAH, which has made some of the most important discoveries in this field. "BSE Tests Conducted on Wrong Brains," cried a headline in the London Times. Bostock complains that the British press has pronounced the IAH guilty of making a mistake before all the proof is in. "If there is an error on our part, we will state that," he says. Until then, Bostock insists, there should be no rush to judgment: "We have to balance this with a decade of high-quality work in this field."

Epidemiologist Peter Smith, chair of the government's Spongiform Encephalopathy Advisory Committee, says it "would be wise to withhold judgment" about what really happened. Smith adds that, after all, the affair provides "no reassurance" that sheep don't harbor BSE.

Related sites

Institute for Animal Health
U.K. Food Standards Agency
BSE Controls Review Web site