Background. Transmissible spongiform encephalopathies (TSEs) or prion
diseases are a unique group of neurodegenerative diseases of animals and
humans, which always have a fatal outcome and are transmissible among animals
of the same or different species. Scope and Approach. The aim of this work is
to review some recent data about animal TSEs, with the emphasis on their
causative agents and zoonotic potential, and to discuss why the surveillance
and control measures over animal TSEs should remain in force. Key Findings
and Conclusions. We still have incomplete knowledge of prions and prion
diseases. Scrapie has been present for a very long time and controlled with
varied success. Bovine spongiform encephalopathy (BSE) emerged unnoticed, and
spread within a few years to epidemic proportions, entailing enormous
economic consequences and public concerns. Currently, the classical BSE
epidemic is under control, but atypical cases do, and probably will, persist
in bovine populations. The Chronic Wasting Disease (CWD) of the cervids has
been spreading in North America and has recently been detected in Europe.
Preventive measures for the control of classical BSE remain in force,
including the feed ban and removal of specified risk materials. However,
active BSE surveillance has considerably decreased. In the absence of such
preventive and control measures, atypical BSE cases in healthy slaughtered
bovines might persist in the human food chain, and BSE prions might
resurface. Moreover, other prion strains might emerge and spread undetected
if the appropriate preventive and surveillance measures were to cease,
leaving behind inestimable consequences.