Bovine spongiform encephalopathy, or BSE, one of a group of rare neurodegenerative disorders called transmissible spongiform encephalopathies, has no reliable non-invasive test for detecting infection before the onset of clinical disease.

In addition to BSE, these diseases include scrapie, a closely related disease in sheep, and Creutzfeld-Jakob disease, or CJD, in humans, which causes neurological symptoms such as unsteadiness and involuntary movements that develop as the illness progresses, rendering late-stage sufferers completely immobile at the time of death.

The nine-year study conducted at the University of Edinburgh compared rates of disease transmission by examining blood transfusions from sheep infected with BSE or scrapie; the BSE donors were experimentally infected, while the scrapie donors had naturally acquired the disease.

The outcome of the experiment, published in the journal Blood, showed that both BSE and scrapie could be effectively transmitted between sheep by blood transfusion. The team noted that transmission could occur when blood was collected from donors before they developed signs of disease, but was more likely when they were in the later stages of infection.