BAD NEWS, BUT THIS DOES NOT MEAN OUR BEEF ISN’T SAFE TO EAT

IT IS bad news that a single case of BSE has been confirmed in a beef herd near Huntly in Aberdeenshire, the first case to be confirmed in Scotland for a decade.

But any kind of panic would be quite out of order. The risk to humans is zero. Scottish beef is perfectly safe.

The first case of BSE in the world occurred in a cow in Sussex. It fell ill in 1984. It was a brand new disease.

By 1987 there had been about 150 cases. Evidence was building that the disease was being spread by recycling; meat and bone meal from cattle was being fed to other cattle as a source of protein.

It was thought to be a perfectly safe practice because the meat and bone meal was treated in ways which would destroy well-known bugs such as salmonella. But the agent that causes BSE is extraordinarily tough. Boiling does not kill it.

Feeding cattle with meat and bone meal was banned in 1988, when meat from animals with BSE was prohibited from entering the human food chain.

In the following year cow brain and spinal cord were categorised as ‘risk offals’ and banned as a human food. It was hoped these controls would be the end of the matter.

But in 1995 several very unusual cases of Creutzfeldt-Jakob disease (CJD) – an unpleasant and rapidly developing lethal kind of dementia – were diagnosed. They were unusual because they were in young people. BSE had spread to humans. There was an enormous worry that there would be a massive epidemic. Many thousands of people had eaten products from cattle infected with BSE before the controls had come in. But the number of cases has turned out to be much smaller than feared: so far they number 178.

The outbreak peaked in 2000, when 28 people died from the disease, now called variant vCJD. The last case died in 2016, and none has been diagnosed since. In a sense the controls worked, in that nobody born after the offal ban has developed the disease from eating beef products.

Both BSE and vCJD are slow diseases in that years can go by between an animal or a person being infected and falling ill.

THAT is why the number of cases of BSE peaked long after the implementation of effective control measures; the peak number of UK cases – 37,280 – occurred in 1992. There has been a constant decline ever since, with 1,443 cases in 2000, 11 in 2010, and none in 2016.

However, I am not surprised about the single Aberdeenshire case this week. Single sporadic cases have been diagnosed in other countries.

In all probability that is how our own UK epidemic started in the 1980s, taking off because of the use of meat and bone meal. But without that, the case will stay a single one. The disease does not spread to other animals. It is not like foot and mouth disease, which spreads on the wind.

Many aspects of the science underpinning our understanding of BSE and vCJD are still unclear. We know enough about them to stop them spreading, but not enough to explain why single sporadic cases happen, or to devise treatments that work.

We do not know why cases of vCJD were measurably more common in northern England and Scotland than points south.

A world-leading centre is located in Edinburgh, the National CJD Research and Surveillance Unit. It was established in 1990 as part of the response to BSE.

Most of its work is done on CJD, which remains a big scientific puzzle. Most cases affect the elderly and occur out of the blue – they are sporadic. They have nothing to do with BSE.

It is certain that people with a particular genetic make-up are more likely to get CJD (and vCJD). We don’t know why.

There are still arguments about the make-up of the BSE/vCJD/ CJD causative agent. All agree that it is not a bacterium nor a virus.

We know that rarely it can be transmitted from person to person under unusual and very special circumstances. Tragedies have occurred when the agent was present in growth hormone extracted from pituitary glands, and when portions of the membrane lining the brain was used in transplants.

A Nobel Prize was given to Stanley Prusiner for his research on it. He called it a ‘prion’, and considers it to be a very unusual protein.

Some of us are not so sure. We think a small nucleic acid may be involved as well. It is an important scientific question because Prusiner’s ideas are very influential in driving other research programmes, notably on far commoner dementias such as Alzheimer’s disease.

The very bad BSE times in the 1980s and 1990s left their mark. Lessons were learned. One thing that comes out of the Aberdeenshire case is that they have not been forgotten. We can be confident no risks will be taken, and any control measures will almost certainly verge on the draconian.

It can be said without any exaggeration that British beef is the safest in the world.

My only worry is that some ill-conditioned person uses a single sporadic case of BSE in the most highly regulated industry in the world as a constraint on exports in trade negotiations.

It is impossible to escape Brexit these days.

Hugh Pennington is Emeritus Professor of Bacteriology at the University of Aberdeen.