Experts will, for example, look at any possible links between victims and GP practices, vaccines, water supplies and workplaces. Families of the deceased will be asked to complete questionnaires about their loved ones' lives. Every potential common link will be looked at. The difficulty is judging when something has become statistically significant'. Ninety people have died from vCJD since March 1995 while seven more are currently thought to be dying.
Scientists are reluctant to predict the eventual toll.
A study of the victims so far appears to suggest that northerners are twice as likely as southerners to be struck down. Simon Cousens, an epidemiolo-gist who led the study by the London School of Hygiene and Tropical Medicine and the CJD Surveillance Unit, discovered where 84 of the known victims were living in early 1991. The main finding is that the incidence of vCJD is twice as high in the northern half of Britain as it is in the south, ' said Mr Cousens. Data from the Government's annual household food survey suggests significantly more processed meat products were eaten in areas with the highest number of cases of the disease. The practice, widely used to produce cheap food, was not banned until 1995.