Abstract
We extended an existing back-calculation model to analyse data on reported clinical cases of bovine spongiform encephalopathy (BSE), data from random testing of healthy animals slaughtered in abattoirs and testing data from animals reported as sick or dying on the farm. Extensive analysis of demographic data was also undertaken. We estimated past and current BSE infection prevalences in the cattle population and the degree of case under-ascertainment resulting from excess mortality in cattle near to disease onset. Ongoing levels of human exposure to BSE infectivity were also estimated, together with the effect on these of a range of possible exposure-reduction strategies that might replace the current rule banning tissue from cattle over 30 months (OTM) of age from the human food supply. While any policy change that allows a wider age range of animals into the human food supply will increase levels of human exposure to infectivity, the risk posed by such increases is small by comparison with historical exposure levels. Making the pessimistic assumption that there will be 5000 deaths during the variant Creutzfeldt-Jakob disease (vCJD) epidemic in total, our analysis indicates that replacement of the OTM rule with testing would result in 0.04 additional vCJD deaths over the next 60 years. However, there is substantial (more than 40-fold) uncertainty surrounding this estimate, the sources of which are discussed.
Full Text
The Full Text of this article is available as a PDF (135.7 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Anderson R. M., Donnelly C. A., Ferguson N. M., Woolhouse M. E., Watt C. J., Udy H. J., MaWhinney S., Dunstan S. P., Southwood T. R., Wilesmith J. W. Transmission dynamics and epidemiology of BSE in British cattle. Nature. 1996 Aug 29;382(6594):779–788. doi: 10.1038/382779a0. [DOI] [PubMed] [Google Scholar]
- Brookmeyer R., Gail M. H. Minimum size of the acquired immunodeficiency syndrome (AIDS) epidemic in the United States. Lancet. 1986 Dec 6;2(8519):1320–1322. doi: 10.1016/s0140-6736(86)91444-3. [DOI] [PubMed] [Google Scholar]
- Donnelly C. A., Ferguson N. M., Ghani A. C., Woolhouse M. E., Watt C. J., Anderson R. M. The epidemiology of BSE in cattle herds in Great Britain. I. Epidemiological processes, demography of cattle and approaches to control by culling. Philos Trans R Soc Lond B Biol Sci. 1997 Jul 29;352(1355):781–801. doi: 10.1098/rstb.1997.0062. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Donnelly Christl A., Ferguson Neil M., Ghani Azra C., Anderson Roy M. Implications of BSE infection screening data for the scale of the British BSE epidemic and current European infection levels. Proc Biol Sci. 2002 Nov 7;269(1506):2179–2190. doi: 10.1098/rspb.2002.2156. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ferguson N. M., Donnelly C. A., Woolhouse M. E., Anderson R. M. The epidemiology of BSE in cattle herds in Great Britain. II. Model construction and analysis of transmission dynamics. Philos Trans R Soc Lond B Biol Sci. 1997 Jul 29;352(1355):803–838. doi: 10.1098/rstb.1997.0063. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ghani Azra C., Ferguson Neil M., Donnelly Christl A., Anderson Roy M. Factors determining the pattern of the variant Creutzfeldt-Jakob disease (vCJD) epidemic in the UK. Proc Biol Sci. 2003 Apr 7;270(1516):689–698. doi: 10.1098/rspb.2002.2313. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Isham V. Estimation of the incidence of HIV infection. Philos Trans R Soc Lond B Biol Sci. 1989 Sep 5;325(1226):113–121. doi: 10.1098/rstb.1989.0076. [DOI] [PubMed] [Google Scholar]
- Wells G. A., Scott A. C., Johnson C. T., Gunning R. F., Hancock R. D., Jeffrey M., Dawson M., Bradley R. A novel progressive spongiform encephalopathy in cattle. Vet Rec. 1987 Oct 31;121(18):419–420. doi: 10.1136/vr.121.18.419. [DOI] [PubMed] [Google Scholar]
- d'Aignaux J. N., Cousens S. N., Smith P. G. Predictability of the UK variant Creutzfeldt-Jakob disease epidemic. Science. 2001 Oct 25;294(5547):1729–1731. doi: 10.1126/science.1064748. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.