Two decades have passed since the Bovine spongiform encephalopathy (BSE) epidemic struck Europe. Commonly known as mad cow disease, BSE remains without a cure and, after a long incubation period of 2 to 5 years, is completely fatal due to the spongiform degeneration of the brain and spiral cord.
Europe’s 1986-1998 BSE epidemic was primary focused on the United Kingdom with more than 180,000 cattle infected, requiring an eradication program to put the fire out that ended only after the destruction of 4.4 million cows.
During the epidemic, Europe also experienced 229 deaths of people — 177 in the UK and 52 in other EU countries that were supplied with British beef or beef products — due to new variant Creutzfeldt-Jakob disease (vCJD), the name for BSE once transmitted to humans.
The world response to bovine spongiform encephalopathy (BSE) after that crisis has significantly reduced prevalence of the disease in cattle. However, because isolated cases are still being reported in the European Union (EU), the European Commission asked the European Food Safety Authority (EFSA) to investigate their origin.
EFSA, based in Parma, Italy, provides independent scientific advice and communicates on existing and emerging risks associated with the EU’s food chain.
EFSA believes the key measure for controlling BSE in the EU is a ban on the use of animal proteins in livestock feed. This is because BSE can be transmitted to cattle through contaminated feed, mainly in the first year of life.
Sixty cases of classical BSE have been reported in cattle born after the EU ban was enforced in 2001. None of these animals entered the food chain. Classical BSE is the type of BSE transmissible to humans. The Commission asked EFSA to determine if these cases were caused by contaminated feed or whether they occurred spontaneously, i.e. without an apparent cause.
EFSA experts concluded 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.
Experts could not rule out other causes due to the difficulty of investigating individual cases. Some constraints are the long incubation period of the disease and the lack of detailed information available from farms at the time of the trace-back investigation.
EFSA experts made a series of recommendations to maintain and strengthen the EU monitoring and reporting system, and to evaluate new scientific data that become available.
The European response to BSE
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, according to EFSA, is designed to prevent the entry of BSE-contaminated meat into the food chain.
Four BSE-infected cows have been identified in the United States, the first being in 2003. None entered the food chain and each was an isolated case.
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