Scarcely has the number of BSE cases decreased that the first voices have been raised to ease measures taken to contain BSE. For purely economical reasons, these people recommend relaxation of feed restrictions and reduction of BSE testing, thereby risking a new BSE epidemic.
We know that BSE can be transmitted to humans by consumption of tainted beef, causing variant Creutzfeldt-Jakob disease (vCJD). Furthermore, vCJD can spread between humans. On February 10th 2006, a third vCJD case associated to blood transfusion was reported. The third vCJD case occurred in a relatively small group (less than 30) of individuals - still living today - that received blood from donors, who later developed vCJD. This indicates that human-to-human transmissions may be very efficient. However, many unknowns and uncertainties remain.
To date, over 170 vCJD cases have been identified - most of them in the UK. Has the peak of vCJD incidence passed or is it still to come? People infected with vCJD do not necessarily show symptoms. A study by Hill and colleagues in 1999 on tonsil and/or appendix biopsies indicated that the incidence of infection may be significantly higher than the incidence of clinical disease. Therefore, it is impossible to get an idea of the real occurrence of vCJD. This poses a hypothetical threat, since even those that do not fall ill themselves, may still carry the disease and transmit the TSE agent via blood, tissue transplantations or surgical instruments. Once a critical number of humans get infected with the TSE agent the disease can no longer be controlled.
In this issue of eSCOPE we address the progress in development of blood tests. Efficient ante mortem tests would certainly help reduce the risk of human-to-human transmissions. But it is equally important to halt the epidemic at its roots. BSE is still a ubiquitous cattle disease. To give an idea of the potential for spread: the meat of one BSE cow lands on average on 1000 plates and could potentially infect the same number of human beings. The prevention of new vCJD infections via the consumption of BSE tainted beef continues to deserve our full attention.
Marjan van der Haar
Corporate Communications
