When did bovine spongiform encephalopathy (BSE) start ? Implications on the prediction of a new variant of Creutzfeldt-Jakob disease (nvCJD) epidemic.
Background Knowing the starting date of the BSE epidemic and its size at the very beginning is crucial to interpret the timing of the nvCJD cases and to forecast the nvCJD epidemic.
The first cases occurred in 1985.
The models devised by Anderson (back-calculation) and Dealler (age-period-cohort) led to an estimate of less than 50 cases in 1983, and none earlier.
Here, we applied age-cohort models to the BSE data in order to estimate the earliest possible date of the first unrecognized BSE cases.
Methods The numbers of confirmed BSE cases in the UK, by age group and by calendar year from 1988 to 1996, were analysed by Poisson regression.
The cases'age distribution was considered as constant between the different birth cohorts.
The herd's age structure was taken into account.
Results According to the models, BSE cases may have occurred as early as 1980.
The expected number of cases before 1990 is almost twice the number of confirmed cases and exceeds by more than 20% the expected value of Anderson's model.
The scenario of first human exposure in 1980 leads to fewer future nvCJD cases than predicted by Cousens with exposure patterns starting in 1983 or 1985. conclusion The first birth cohort available, consisting of two cases older than 10 in 1988, does not allow any projections before 1980. (...)
Mots-clés Pascal : Encéphalopathie spongiforme Creutzfeldt Jakob, Infection, Estimation, Incidence, Modèle mathématique, Epidémiologie, Prédiction, Méthodologie, Homme, Bovin, Artiodactyla, Ungulata, Mammalia, Vertebrata, Animal, Prion, Système nerveux pathologie, Système nerveux central pathologie, Encéphale pathologie, Maladie dégénérative
Mots-clés Pascal anglais : Creutzfeldt Jakob disease, Infection, Estimation, Incidence, Mathematical model, Epidemiology, Prediction, Methodology, Human, Bovine, Artiodactyla, Ungulata, Mammalia, Vertebrata, Animal, Prion, Nervous system diseases, Central nervous system disease, Cerebral disorder, Degenerative disease
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0339919
Code Inist : 002B17G. Création : 14/12/1999.