Letter: Does BSE harm people?

Sir: Professor Richard Lacey asserts (Another View, 15 November) that BSE is "now established as a cause of sporadic Creutzfeldt-Jakob disease (CJD) in humans".

This is not true. CJD occurs round the world with a relatively constant incidence, including countries that are free of both scrapie and BSE. In 1994, the incidence of CJD in the UK was lower than in the Netherlands and in Austria, which are both free of BSE. The occurrence of CJD in dairy farmers in the UK is unlikely to be directly linked to BSE, because CJD occurs with a similar frequency in dairy farmers in France, Germany and Italy, which are countries with a minimal potential occupational exposure to BSE. The occurrence of CJD in teenagers in the UK is tragic, but this does not establish a link with BSE, because CJD has previously been described in teenagers in other countries in which there could not possibly be a link with BSE.

The primary remit of the CJD Surveillance Unit is to determine whether there is a link between BSE and CJD by detailed investigation of all cases of CJD in the UK. We have not yet established a link and the evidence on which this statement is based has been recently published in an Annual Report. However, it is clearly imperative to continue to study closely the epidemiology of CJD, as the long incubation periods in CJD and other prion-protein diseases indicates that it will be many years before a theoretical link between CJD and BSE can be excluded.

Yours faithfully,

R. G. Will

James W. Ironside

M. Zeidler

National Creutzfeldt-Jakob

Disease Surveillance Unit

Western General Hospital

Edinburgh

15 November