Epidemiological evidence of higher susceptibility to vCJD in the young
Pierre-Yves Boëlle1 
, Jean-Yves Cesbron2 
and Alain-Jacques Valleron1
1 INSERM U444, Assistance Publique Hôpitaux de Paris, Université Pierre et Marie Curie, Paris, France
2 Immunité Anti-Infectieuse JE 2236, UFR de Médecine de Grenoble, Université Joseph Fourier, Grenoble, France
author email
corresponding author email
BMC Infectious Diseases 2004, 4:26doi:10.1186/1471-2334-4-26
Abstract
Background
The strikingly young age of new variant Creutzfeldt-Jacob disease (vCJD) cases remains unexplained. Age dependent susceptibility to infection has been put forward, but differential dietary exposure to contaminated food products in the UK population according to age and sex during the bovine spongiform encephalopathy (BSE) epidemic may provide a simpler explanation.
Methods
Using recently published estimates of dietary exposure in mathematical models of the epidemiology of the new variant Creutzfeldt Jacob disease (vCJD), we examine whether the age characteristics of vCJD cases may be reproduced.
Results
The susceptibility/exposure risk function has likely peaked in adolescents and was followed by a sharp decrease with age, evocative of the profile of exposure to bovine material consumption according to age. However, assuming that the risk of contamination was proportional to exposure, with no age dependent susceptibility, the model failed to reproduce the observed age characteristics of the vCJD cases: The predicted cumulated proportion of cases over 40 years was 48%, in strong disagreement with the observed 10%. Incorporating age dependent susceptibility led to a cumulated proportion of cases over 40 years old of 12%.
Conclusions
This analysis provides evidence that differential dietary exposure alone fails to explain the pattern of age in vCJD cases. Decreasing age related susceptibility is required to reproduce the characteristics of the age distribution of vCJD cases.
