Lessons of mad cow disease ‘in danger of being lost’

Mad cow disease may be over but we shouldn’t forget the lessons learned or relax food safety regulations, warned Professor Richard Knight, the director of the National CJD Research and Surveillance Unit. 

Knight, a neurology professor, appears in a BBC Two programme tonight (11 July) that examines the events surrounding the bovine spongiform encephalopathy (BSE) meat scandal.

BSE was spread among UK herds by feeding infected beef to cows: parts of the cow that humans didn’t eat were cooked, dried, powdered and put into animal feed. BSE then spread to humans as food manufacturers developed new ways to use more of the animal carcass, mechanically recovering previously unwanted parts of the cow – often the brain and spinal cord – to put in pies and sausages.

The programme also interviews Daily Mirror journalist Kevin Maguire, who broke the story in March 1996 that BSE could cross species and infect humans, causing an incurable degenerative brain disease: Variant Creutzfeldt-Jakob disease (vCJD). He told the programme makers: “It was a scandal – that hunger to get every penny profit out of a carcass. It was almost as if capitalism went mad and literally began to eat itself.”

Knight echoed these sentiments. He said: “Underlying all of this was the desire to have excessive amounts of, and readily available, cheap meat.”

Knight added: “The thing that worries me is because all of this in some sense is over, people are talking about relaxing animal regulations – though they have not gone back to ruminants feeding ruminants again – and what’s driving that is economics.

“There are people who say it’s okay because BSE has gone. Many of us who have been through this period from the scientific point of view see that people’s memories are short and they haven’t been able to learn the lessons.”

There is no simple diagnostic test for vCJD, which was why the surveillance unit has been set up at Edinburgh University comprising neurologists, pathologists and diagnosticians. Attempts have been made to create a test, and most scientists believe the disease is caused by changes in prion proteins.

The number of deaths from definite or probable vCJD between 1995 and 2019 is 178. However, it has a long incubation period and beyond being sure that there will be more deaths, huge uncertainty remains.

Knight said: “People have forgotten about it and because they haven’t heard anything they assume nothing is happening. It’s always been anticipated that there will be more cases but hopefully over a longer period and not very many.

“The modeling is based on assumptions but it’s always been thought there would be more cases because in epidemics like this there are people with varying genetics and exposures. And these diseases have long incubation periods.”

Everyone who has been diagnosed with vCJD has died from the disease, but it is not known whether it can be carried subclinically. In many countries people who lived in the UK for more than six months during exposure period of 1980 to 1996 are banned from giving blood.

Knight added: “Just one more case would be very bad but if you go back in time, there was a suggestion that there could be 500,000 more cases – no one is now expecting that huge epidemic of cases.”

To date there have been no UK cases of vCJD in people born after 1989, when measures were put in place to protect the human diet from BSE.

• Mad Cow Disease: The Great British Beef Scandal airs tonight (11 July) at 9pm on BBC Two.