Predicting the size of the vCJD epidemic in France.

More than 5 years after the description of the first cases of variant Creutzfeldt-Jakob disease (vCJD), there is still great uncertainty about the size of the vCJD epidemic in the United Kingdom (UK), although the most recent predictions based on statistical modelling are more optimistic than the previous ones. The number of vCJD cases in France is far too small to attempt any direct modelling of the vCJD epidemic in the French population. Comparative assessment of the level of exposure to the bovine spongiform encephalopathy (BSE) agent in the UK and France could help to estimate the size of the vCJD epidemic in France. Data on imports of beef products from the UK between 1985 and 1996, BSE epidemic in French cattle, and travel of French people to the UK suggest that the French population was much less exposed to the BSE agent than the UK population. The France/UK ratio of vCJD incidence is currently approximately equal to 0.05. Further studies are needed to estimate accurately the exposure ratio between UK and France and to examine whether comparative data about exposure and incidence are fully consistent. The temporal pattern of exposure in UK and France, and possible differences in exposure to high risk bovine tissues because of food habits or risk reduction measures should be carefully considered.