Contaminated feed likely cause of 60 BSE cases in EU since ban: EFSA

By Jane Byrne contact

- Last updated on GMT

© istock/Franck Boston
© istock/Franck Boston
European Food Safety Authority (EFSA) experts have concluded that contaminated feed was the most probably source of infection in the 60 BSE cases that have occurred in the EU after the 2001 feed ban was enforced.

They said 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,”​ noted the BIOHAZ panel. 

The key measure for controlling bovine spongiform encephalopathy (BSE) in the EU is a ban on the use of animal proteins in livestock feed as BSE can be transmitted to cattle through contaminated feed, mainly in the first year of life.

One of the Authority’s recommendations, following its probe into the origins of those BSE cases, is that the Commission strengthens the EU monitoring and reporting system and create an EU-level system for the collection, collation and analysis of feed testing data from the EU-28.

Background to investigation

While the European response to after the crisis of the 1980s has significantly reduced prevalence of the disease in cattle, 60 cases of classical BSE - the type of BSE transmissible to humans - were reported in cattle born after the EU ban was enforced in 2001.

None of these animals entered the food chain, but the EU Commission asked EFSA to investigate their origin.

EFSA was asked to determine if these cases were caused by contaminated feed or whether they occurred spontaneously - without an apparent cause.

The EFSA scientists said they could not rule out causes other than tainted feedstuffs due to the difficulty of investigating individual cases. They cited certain constraints such as the long incubation period of the disease and the lack of detailed information available from farms at the time of the trace-back investigation.

“The source of infection cannot be ascertained at the individual level for any BSE case, including these BARB-60 cases, so uncertainty remains high about the origin of disease in each of these animals, but when compared with other biologically plausible sources of infection (maternal, environmental, genetic, iatrogenic), feed-borne exposure is the most likely.”

The team noted that despite the large number of feed samples tested in the EU and the high analytical sensitivity of the tests in place, in the context of the huge volumes of ingredients used for the production of livestock feed, the feed surveillance system has limited sensitivity for the detection of low levels of contaminated material.

“Infectivity, if present, is likely to be concentrated in small amounts in the form of lumps of infected material.”

The EFSA report said there was an overall effort to comply with the TSE legislation with regard to the enforcement of the total feed ban in the EU-28. “Over time, the deficiencies observed by the FVO [Food and Veterinary Office] teams in the early years of the implementation were progressively overcome by measures applied by MS.”

“However, contaminated material was still present in the EU after the total feed ban, as documented in the FVO audit reports. Within the national feed audits, animal protein has been detected in feed samples after 2001.”

EFSA’s findings can be accessed here​.

The coordinated European response to BSE has succeeded in reducing the prevalence of the disease. Between 2005 and 2015 about 73,000,000 cattle were tested for BSE in the EU, out of which 60 born after the ban tested positive for classical BSE. The number of affected animals rises to 1,259 if cattle born before the ban are included. The number of classical BSE cases has dropped significantly in the EU over time, from 554 cases reported in 2005 to just two in 2015 (both animals born after the ban). Moreover the EU food safety system is designed to prevent the entry of BSE-contaminated meat into the food chain (Source: EFSA)

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