Sore throat link to CJD

vCJD is the human form of mad cow disease

By the BBC's Matt McGrath

The victims of vCJD may have succumbed to the disease because they ate contaminated beef when they were suffering from a bout of tonsillitis or a simple sore throat.

Could it be that these patients had a sore throat and they were just unlucky that they ate a sausage or a meat pie that had a lot of BSE brain associated with it?

Professor Stephen DeArmond, UCSF

The theory has been put forward by a leading American scientist, Professor Stephen DeArmond, from the University of California at San Francisco.

He said it could explain why relatively few people had been struck down with the illness so far and why so many of those who had were under the age of 35.

British researchers studying vCJD said the theory was plausible but stressed there was no experimental data to support it.

Scientists still know very little about why the variant form of Creutzfeldt-Jacob disease seems to strike some people and not others.

Exact route

To date, it has killed 94 people in the UK. Another eight are suspected sufferers and are still alive.

Researchers believe the illness is caused by infectious proteins called prions being passed to humans through meat contaminated with the brains and spinal tissue of cattle suffering from BSE, or mad cow disease. But the exact route remains a mystery.

Now, Professor DeArmond, one of the world's leading prion experts, has told the BBC that inflammation in the throat area of victims could be the key factor.

"All I am trying to do is search for something that would get the protein into the lymphoreticular system, particularly into the tonsils, and certainly some irritation there, injury or inflammation, might have been one way that these 90-odd people were unlucky," he said.

Prion reservoirs

The tonsils are an important focus for research because they are known to be a reservoir for prions.

It is this fact that has prompted British hospitals to dispose of all surgical implements used in tonsillectomies, to counter the very slight risk that the equipment could pass vCJD from one patient to another.

But Professor DeArmond said serious consideration was now being given to the idea that the tonsils were the route through which the primary infection from cattle to humans occurred.

"Why does it [the infection] get into the tonsils for instance and it doesn't happen in sporadic CJD or any other forms of CJD that we know of.

"Could it be that these patients had a sore throat and they were just unlucky that they ate a sausage or a meat pie that had a lot of BSE brain associated with it?

"Again, I'm trying to think of any other factor that would explain why a relatively small number of individuals would get the disease."

With perhaps 30% to 40% of the British population having the genetic make-up susceptible to vCJD infection, and so many contaminated meals eaten over the years, Professor DeArmond said one could have expected many more victims to have emerged by now.

Age profile

However, if sore throats had acted as a contributory, but limiting, factor, it might also explain the age profile of vCJD victims.

Young people go through a lot of colds and sore throats that you become immune to later in life

Professor Stephen DeArmond, UCSF

"Young people go through a lot of colds and sore throats that you become immune to later in life," Professor DeArmond said.

"As you get older, you experience more viruses and you reach a stage where you become less susceptible to these problems."

Researchers in the UK said the ideas expressed by Professor DeArmond were plausible but nothing had been proven.

Teeth theory

"The truth is we don't know what the reason is for the particular age distribution of the vCJD cases that have been observed so far," said Professor Peter Smith, the acting chairman of the government's Spongiform Encephalopathy Advisory Committee (Seac).

"There are a lot of changes that take place around adolescence. Other people have suggested for example that it may be related to the sort of changes in teeth that take place at around that age - with some dental procedures there may be a risk.

"These are all possible hypotheses but we really don't know."

The UCSF professor is a colleague of Stanley Prusiner, the scientist honoured with a Nobel Prize for his pioneering work on prions. Californian researchers are now developing a therapy that will block the action of infectious prions.

The therapy, which has shown promise in the lab, will go into animal trials in the next 12 months. If these experiments are successful, they could lead to an effective treatment for spongiform diseases in humans within 10 years, Professor DeArmond said.