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Estimation of the age-dependent risk of infection to BSE of dairy cattle in Great Britain |
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| Authors: | Arnold M E Wilesmith J W |
| Institution: | aCentre for Epidemiology and Risk Analysis, VLA, New Haw, Addlestone, Surrey KT15 3NB, UK bThe Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, University of London, Keppel Street, London WC1E 7HT, UK |
| Abstract: | An important aspect of the bovine spongiform encephalopathy (BSE) epidemic has been an apparent age-dependent risk of infection, with younger cattle being more likely to become infected than older cattle. Our objective was to determine the age-dependent risk of infection of dairy cattle. We first reviewed unpublished data on the feeding patterns of proprietary concentrates for dairy-replacement cattle. These data showed that autumn- and spring-born cattle would receive different feeding patterns of proprietary concentrates, and so age-dependent risk of infection profiles were obtained separately for autumn- and spring-born cattle. We used back-calculation methods to analyse BSE-epidemic data collected in Great Britain between 1984 and 1996. Dairy cattle were most at risk in the first 6 months of life; adult cattle were at relatively low risk of infection. Between 6 and 24 months of age, risk profiles reflected feeding patterns of proprietary concentrates in each of the autumn- and spring-born cohorts. |
| Keywords: | Bovine spongiform encephalopathy Modelling Age-dependent susceptibility Epidemiology Back-calculation |
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