A joint opinion reviewing the latest available scientific information on possible links between Transmissible Spongiform Encephalopathies (TSEs) in animals and humans has been published by the European Food Safety Authority (EFSA) and the European Centre for Disease Prevention and Control (ECDC). At present, the only TSE proven to be zoonotic (i.e. transmissible from animals to humans), remains Classical Bovine Spongiform Encephalopathy (BSE), known in humans as variant Creutzfeldt-Jakob disease (vCJD), the findings in the opinion confirm.
Epidemiological evidence shows the most common form of TSE in humans is sporadic Creutzfeldt-Jakob disease (sCJD). The cause of sporadic CJD remains uncertain. Although scientific research to date has not identified an environmental source of infection, the panel could not exclude the possibility that a small number of cases could be zoonotic.
No epidemiological evidence suggests Classical scrapie in goats and sheep, is zoonotic. Regarding Atypical scrapie in sheep and goats, the scientific data currently available are too limited to conclude whether it has the potential to be zoonotic or not.
For other TSEs, some uncertainties make it currently impossible to make definite conclusions on possible links between animals and humans. One reason for this is data on the monitoring of TSEs in animals are too recent to be compared to the respective human data. As a result, the opinion recommends systematic monitoring of TSE diseases be continued in both humans and animals.
Scientists also evaluated evidence obtained from experimental transmission of TSEs in laboratory studies. The results of some of these studies suggest there might be a possibility of animal-to-human transfer for other TSEs, in addition to Classical BSE in cattle, the opinion states. Some data indicate one of the new atypical BSE agents, the L-BSE or BASE agent, may have a similar or higher zoonotic potential than the Classical BSE agent.
However, the opinion points out at present it is not possible to define how informative these laboratory studies are for measuring the transfer of TSEs between animals and humans under real exposure conditions.
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