IT was 20 years ago today that scientists confirmed the truly shocking news that Bovine Spongiform Encephalopathy, or BSE, was indeed the cause of degenerative brain disease in humans.

It was a critical moment in the long BSE scandal that began in 1986 with a field of cows losing their balance. Now there was proof that the disease had indeed jumped the species barrier and was killing humans. The reaction was one of utter shock on the part of almost the entire population of beef-eating countries across the globe.

More than 20 people had died in Britain in the previous few months from so-called new variant Creutzfeldt-Jakob disease (nvCJD), a brain disease for which there was no cure. The public had long suspected “mad cow disease” was also affecting humans, but beef consumers were assured there was no link.

For several years, the government had declared there was no link between BSE and nvCJD, with agriculture minister John Selwyn Gummer famously going on television in 1990 to feed his daughter a burger.

But as the evidence mounted, John Major’s government commissioned more research and in March 1996 health minister Stephen Dorrell conceded there might be a link.

The European Commission promptly banned all British beef products from Europe, and yet another row broke out between the UK and EU.

BUT SURELY ALL THE BSE-INFECTED CATTLE WERE DESTROYED?

THAT was the theory. By 1995, cases of BSE in British cattle had topped 150,000. In France it was even worse, with double that number of cases.

The early signs were that cows contracted BSE by eating food derived from the tissues of infected cattle. An inquiry in Britain and Ireland showed that to be the case. That practice of feeding cattle meat-and-bone meal was banned as long ago as 1988, when the slaughter and destruction of cattle suspected of having BSE was made compulsory.

Certain types of offal from cows were also banned from the human food chain. The problem was that about 500,000 infected animals had entered the food chain before the bans took effect.

Tragically, even young people who had not eaten meat for years died of ncCJD.

WHO FOUND THE LINK?

REMARKABLY, two scientists working many miles apart both found separate evidence that proved the link. They were looking at prions, which are misshaped proteins that accumulate in the brain and cause degeneration.

Thanks to the Biotechnology and Biological Sciences Research Council and Medical Research Council, funding had been allocated to a major scientific research project to find the cause of BSE and nvCJD.

Not surprisingly, given that the UK Government had established the chief unit in Edinburgh to research nvCJD, it was a Scottish doctor who featured in the news on October 2, 1997.

Dr Moira Bruce, working with a number of colleagues at Edinburgh’s Institute for Animal Health, published in that week’s Nature magazine the interim results of their research into transmissions of sporadic CJD and nvCJD to mice.

Bruce concluded: “Our data provide strong evidence that the same agent strain is involved in both BSE and vCJD.”

At the same time, Professor John Collinge in London made the same conclusion public. An expert in prion diseases, he demonstrated that the prion strain in nvCJD matched that from BSE in cattle.

Collinge had also developed a blood test for early diagnosis of nvCJD. He had actually gone public in October 1996 with his fears that nvCJD was linked to BSE, to which the Department of Health responded: “the evidence is not conclusive, but it is persuasive.”

By the following September, Bruce and Collinge had proven beyond a reasonable doubt that “mad cow disease” was killing humans too.

WHAT HAPPENED NEXT?

APART from more panic, not least because nvCJD could take many years to develop in the human brain, the response was firm. Tony Blair’s New Labour government was determined to get British beef safe, and culling that had begun earlier in the year was extended massively. In effect, all cattle that could possibly be carriers were destroyed.

Later that year American biologist Stanley B Prusiner won the Nobel Prize for Physiology or Medicine for discovering prions, though some scientists still dispute exactly how BSE is transmitted.

There is still no cure for nvCJD. About 200 Britons are thought to have died of the disease in recent years.