Risk of variant Creutzfeldt-Jakob disease in France

France has the second highest number of variant Creutzfeldt-Jakob disease (vCJD) cases worldwide. Imports of bovine carcasses from the UK probably constituted the main source of exposure of the French population to the bovine spongiform encephalopathy (BSE) agent. Meat products consumed whilst visiting the UK have also been considered as a possible source of exposure.

We estimated the number of future vCJD cases in France using a simulation approach. Both the distribution of the vCJD incubation period and the age-dependent susceptibility to the BSE agent were estimated from UK data. The French epidemic was simulated by gender and birth-cohort from data on the infectivity of UK bovine tissues and simulations of the French consumption of infected beef products. We also used data on travel to the UK between 1980 and 1995.

We predicted 33 future cases of vCJD: 12 in the 1940-69 birth-cohort and 21 in the post-1969 birth-cohort. No case was predicted in the pre-1940 cohort. Based on our model, simulated vCJD cases occurred later in the older (1940-69) than in the younger cohort (post-1969). Age at onset was stable in the post-1969 cohort and increased in the older cohort. The model predicted a small excess of male patients. No case was attributed to travels in the UK.

This modelling confirms that a large vCJD epidemic in France is very unlikely. Since France (where 60% of the total British exports of bovine carcasses were exported) has been highly exposed to the BSE agent, our results are reassuring for most countries worldwide.