The risk of contracting vCJD the human form of BSE is twice as high in the North as in the South, according to a medical specialist who criticised the food industry yesterday for blocking a scientific study to find out why.
Professor James Ironside, of the National CJD Surveillance Unit in Edinburgh, said there were now 106 confirmed cases of the human brain disease. He said the latest figures showed that the rate of increase was now more than 20 per cent greater than it was this time last year.
But people in northern England and Scotland appear to be at twice the risk of developing vCJD, compared with people living in southern England and Wales, which could reflect a difference in exposure to BSE 10 or 15 years ago when the cattle epidemic was at its height. Professor Ironside said: "My statisticians and epidemiological colleagues all agree that this is a real observation, so instead of moving from a flat line we're now seeing an upward trend and that is being sustained over the past four quarters. Whether it will continue to be sustained obviously remains to be seen."
Each case is extensively investigated, with the relatives of the patients being asked about lifestyle and eating habits dating back many years. But scientists want more information from the food industry on the use of cheap, mechanically recovered meat, which is believed to have been at greatest risk of contamination with BSE.
Professor Ironside told the British Association science festival in Glasgow: "One of the difficulties in this research when we carry out our case-control study is the ongoing lack of information from the food industry as to what type of products mechanically recovered meat went into.
"We could focus our questionnaire much more efficiently if we knew that."
The food industry denies it has been obstructive. Bill Jermey, president of the British Meat Manufacturers' Association, said his organisation had co-operated fully with the Government's Spongiform Encephalopathy Advisory Committee (Seac).
But Professor Ironside disputed this. "That's not my understanding and if you talk to the chairman of Seac and other members of Seac they will share my views on this," he told The Independent.
"We still have a woeful lack of information on precisely the type of food products that mechanically recovered meat went into. If we knew this it would help to focus our questions more efficiently."
Although the total number of cases of vCJD is roughly equal in the North and the South, the difference in total population means the rate per million people is 2.71 in the North and 1.47 in the South.
Professsor Ironside said: "We find that the rate of vCJD in terms of cases per million is roughly twice in the North compared to the South. I think this is not just a blip because it's been observed over quite a period now, so it seems to be quite a firm finding and of course it raises another question as to why that might be."
One possibility is that there are minor genetic differences in the population, which could make Northerners more susceptible, although scientists think that this is unlikely.
Another possible explanation is that people in the North were more likely to eat cheaper cuts of meat that included mechanically recovered meat contaminated with BSE.
If scientists could estimate how much BSE-contaminated material entered the human food chain, they could give a better insight into the course of the epidemic. Professor Ironside said the lack of this information was making accurate predictions difficult.
"I don't think anyone is in any position to predict where the upward curve of the epidemic is going to go," he said. "The parameters that might affect the upward curve are perhaps widening and we need to look more closely at what the potential explanations for the difference between the North and South ... might be.
"I think what we can say is that some of the worse-case scenarios are now very unlikely. We are not going to see millions of cases."
Mr Jermey said there was no evidence to suggest that meat manufacturing processes and the use of mechanically recovered meat differed substantially from one part of the country to the next. "Certainly most meat products these days are sold all over the country from individual plants," he said.
"We think the use of mechanically recovered meat was far wider than our members. It's possible that the worst use of mechanically recovered meat took place in many of the smaller operations that are no longer in business. It's going to be very difficult to get to the truth of what happened 10 or 15 years ago."