Feed is the most likely cause of infection transmission in the small number of BSE cases across the EU since the turn of the century, although there is no comprehensive proof.

This is the European Food Safety Authority (EFSA)’s conclusion after investigating the issue for the European Commission to ascertain whether the cases were caused by contaminated feed or had occurred spontaneously.

Some 73 million cattle have been tested across the EU for BSE between 2005 and 2015, with just 60 animals born after the 2001 EU ban on animal feed proteins testing positive for classical BSE. The number rises to 1,259 when cattle born before the ban are included. The number of cases reported has dropped from 554 in 2005 to just two in 2015.

 EFSA concludes that contaminated feed is the most likely source of infection. “This is because the infectious agent that causes BSE has the ability to remain active for many years. Cattle may have been exposed to contaminated feed because the BSE infectious agent was present where feed was stored or handled. A second possibility is that contaminated feed ingredients may have been imported from non-EU countries.”  It was not possible to conclude that any of the cases had a spontaneous origin.

But EFSA stresses that other causes can’t be ruled out due to the due to the difficulty of investigating individual cases, the long incubation period, and the lack of detailed information available from farms in view of the time elapsed when tracing back.

The report is available via: https://www.efsa.europa.eu/en/efsajournal/pub/4885