Can you acquire CJD from mutton?

Atypical scrapie has been found in UK sheep. But is it a threat to human health? asks Emma Baines.

What is the story?

A new animal disease which has been found in UK sheep has raised 'the most serious concern about the safety of meat since the discovery of mad cow disease', according to media reports.

They reported that the Food Standards Agency (FSA) had issued a warning saying that it 'could not rule out' a risk to human health from the brain-wasting disease atypical scrapie, which has been discovered in UK sheep.

The papers added that the only way to avoid all risk of contracting the disease was to avoid mutton, goat and sausages made with sheep intestines.

What is the background?

The media reports were written before last week's FSA board meeting, at which a report on atypical scrapie was presented.

Cattle, sheep and goats can suffer from a group of neurological diseases known as transmissible spongiform encephalopathies (TSE). The best known of these is bovine spongiform encephalopathy (BSE) which can be transmitted to humans and cause vCJD.

The TSE most commonly found in sheep and goats is scrapie. This disease is known to have been present in sheep in the UK for over 200 years, and is not transmissible to humans.

However, following the BSE scandal, experts feared that some sheep could have been infected with the bovine form of the disease, potentially posing a human health threat.

In 1998 a programme of testing for scrapie using new and more sensitive testing methods was introduced. This was designed to reduce the number of scrapie-infected sheep in the UK and ensure they were not in fact carrying BSE.

By 2003 a number of sheep had been found to be infected with a TSE which was not the same as scrapie. Further tests showed that the disease was not the same as BSE. This TSE was designated 'atypical scrapie'.

Since then, the disease has been found to be widespread in the UK flock, and also in the EU.

According to a Spongioform Encephalopathy Advisory Committee (SEAC) statement released in February, about 82,000 sheep in Great Britain are currently infected with atypical scrapie, compared to 56,000 with the classical form of the disease.

Because it is impossible to know if atypical scrapie is a new TSE, or just newly detected, it is unclear how much of a risk to human health it presents.

What is the FSA's advice?

The FSA has said: 'It is not possible at the present time to determine what risk, if any, atypical scrapie may present to people.

'Because the possibility of a risk cannot be ruled out, a number of precautionary controls are in place. These include controls on animal feed and removing certain parts of the animal before the meat goes into the food chain.

'While the Agency is not advising anyone to stop eating sheep or goat meat or products, any possible risk could be reduced further by not eating meat from older animals.

'In addition, some sausages are contained in natural sheep casings made from sheep intestines which are more likely to carry the disease agent.'

What do other experts say?

Professor Hugh Pennington, president of the Society for Microbiology, said that there was no reason to believe that atypical scrapie presented any human health threat.

'This atypical scrapie has only come out because we've been looking for scrapie more aggressively. This is bad news for the plan to eliminate scrapie as a disease of sheep, but has nothing to do with human health.

'The nightmare scenario was that sheep were infected with BSE and that it has been there in a hidden way. But there is no evidence that that has happened.'

He added that atypical scrapie was probably not new anyway.

'It might well have been there, but we never found it because we did not look for it. We did not have these sophisticated tests 10 years ago,' he said.

emma.baines@haynet.com

Food Standards Agency

Live links at GPonline.com

WHAT THE PAPERS SAID
"Mutton warning as new disease is found in sheep"
DAILY MAIL
"New warning on mutton as brain disease hits sheep"
THE TIMES
"Food warning over sheep brain disease"
THE DAILY TELEGRAPH

INFORMING PATIENTS

- A brain disease has been found in sheep which belongs to the same family of diseases as scrapie and BSE, but it is not the same as BSE.

- The disease might have always existed, and only have been detected recently because of more sensitive tests.

- Whether or not people can catch the disease by eating infected sheep is not clear.

- Precautionary controls have been put in place.

- The risk of catching it from eating lamb is very low. The risk from eating mutton, goat and some sausages may be higher.

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