More questions than answers

Into the incincerator: The BSE crisis devastated an entire industry

By Environment Correspondent Alex Kirby

More than a decade of research has still not identified the exact cause of BSE, the worst crisis to devastate British farming in modern times.

BSE, or bovine spongiform encephalopathy, is more widely known as "mad cow disease".

Its presence can be established with certainty only after death, when examination of the victim's brain reveals spongy holes in the tissue.

But the stumbling gait and unpredictable behaviour of cattle in the grip of BSE is a good indication.

BSE is one of several similar diseases affecting a number of species, including humans. The best-known human equivalent is Creutzfeldt-Jakob Disease, which is invariably fatal.

Most scientists believe that BSE, first seen in 1984, was caused by feeding cattle with the remains of sheep suffering from another brain disease, scrapie.

Suspect insecticides

Changes in rendering techniques (the treatment of animal remains) are believed to have allowed the infective agent to cross between species.

But sceptics doubt the significance of the changes. Some believe BSE attacked cattle whose immune systems had been weakened by doses of organophosphate insecticides.

The government tried to contain the disease by banning the use of ruminant remains in feed for ruminants, and by paying farmers the full cost of suspect BSE animals.

Its critics say it should have acted faster and not waited for the scientists' advice.

More than a million cattle were killed to try to arrest the epidemic

In 1996, scientists suggested a probable link between BSE and CJD, an announcement which sent the beef industry into freefall.

Within days the European Union had banned all British beef exports.

The ban has gone. But so has the confidence in British meat, and with it many of the traditional markets.

The costs of the crisis are immense - about 175,000 confirmed cases, more than a million cattle slaughtered (most as a precaution) and a £4bn bill.

One theory now holds that eating meat from BSE cattle never posed a risk, suggesting the infection entered the bloodstream through cuts and bites, or through mucous membranes.

Another says there may never have been a risk at all, and that CJD is caused by the body's own reaction to a common bacterium.

Against that, there are concerns over the possible spread of infection through blood plasma, or serum used for vaccines.

The epidemic itself is likely to be almost played out by 2001. The answers may take longer to find.