Likelihood of a large vCJD epidemic remains small claim researchers

The likelihood of a large number of future cases of vCJD remains small claim researchers from Imperial College London.



According to research published today in Journal of the Royal Society Interface, the team believe there will be around 70
future cases of vCJD arising from the consumption of BSE-infected beef. At most this could rise to a total of around 600
deaths, although the researchers feel this is unlikely.


This work follows on from a study in 2003 at Derriford Hospital, Plymouth, which looked at tissue from appendectomies. The
researchers found a higher prevalence of vCJD than expected from clinical data alone, indicating that around 3,800
individuals in the UK could test positive.


The team at Derriford found three positive samples among 12,764 tonsil and appendix samples and from this concluded that
around 3,800 individuals could be at risk across the UK. Despite this, only one of the three samples positively matched
tissues taken from those with clinical disease. The interpretation of the other two samples was less certain, and could
indicate individuals infected with vCJD that do not go on to develop clinical symptoms - so called sub-clinical infections.



Dr Azra Ghani, from Imperial College London, and based at St Mary's Hospital, comments: "Since 2000 there has been a decline
in the number of clinical cases reported. One reason for the discrepancy between the high estimated number of positive tests
and low number of actual recorded clinical cases could be that many infected individuals do not go on to develop clinical
disease in their lifetime."


Using computer modelling the team ran a number of different scenarios. The first scenario in which 90 per cent of infections
are sub-clinical suggested that relatively few future cases would arise through primary transmission, such as eating BSE
infected beef. The other 'worst case' scenario, where all genetic groups were susceptible, suggested that a five fold rise
could be possible, although this was felt to be unlikely, due to the low number of clinical cases currently recorded in these
other genetic groups.


Dr Ghani adds: "Although our results indicate there is little chance of large numbers of vCJD infections from primary
transmission, we have not taken into account the possibility of additional cases infected by blood transfusion. This could
result in more clinical cases emerging at a later date."


Notes to editors:


1. Projections of the future course of the primary vCJD epidemic in the UK: inclusion of sub clinical infection and the
possibility of wider genetic susceptibility, Journal of the Royal Society Interface, 12 January 2005.


2. Consistently rated in the top three UK university institutions, Imperial College London is a world leading science-based
university whose reputation for excellence in teaching and research attracts students (11,000) and staff (6,000) of the
highest international quality. Innovative research at the College explores the interface between science, medicine,
engineering and management and delivers practical solutions that enhance the quality of life and the environment -
underpinned by a dynamic enterprise culture. Website: imperial.ac.uk.


Contact: Tony Stephenson

at.stephensonimperial.ac.uk

44-207-594-6712

Imperial College London