The incidence of variant Creutzfeldt Jacobs Disease (vCJD)—the human form of “Mad Cow Disease”—has increased 20 percent in the UK since last year. In his announcement last week, Professor James Ironside, head of the CJD Surveillance Unit in Edinburgh, said that instead of “a flat line, we are now seeing an upward trend that has been sustained for the past four quarters”. The total number of cases could vary between several hundred and 150,000, he added. Professor Ironside’s unit has released figures showing there are now 106 confirmed or probable cases of vCJD, the fatal and incurable brain wasting disorder in the UK. Most scientific opinion now accepts that the disease is probably related to eating beef infected with BSE (Bovine Spongiform Encephalopathy), or “Mad Cow Disease”.
Ironside also revealed that people in the north of Britain are twice as likely to get the disease as those living in the south. He thought this could be due to differences in genetic make-up, but was more likely to be the result of differences in diet.
Professor Tim Laing, from the Centre for Food Policy, told the BBC that differences in diet were a “class issue”. Cheaper meat products such as pies, sausages and burgers often contained the most infective tissues such as brain and spinal cord, before their use in the human food chain was banned. “Lower-quality meat products tend to be eaten by people on lower incomes, so in the north-south gap we might be seeing the beginnings of a class element to vCJD,” Professor Laing said.
Other scientists are sceptical that regional differences in diet are the cause of a north-south gap in the distribution of vCJD. But the resolution of this scientific question has been hampered by the actions of the food manufacturers, who for several years have refused to give statistics to epidemiologists about the use and distribution of mechanically recovered meat (MRM), a product widely used in meat pies, sausages and so-called “economy burgers” and which has also been included in soups and prepared meals. The MRM slurry is obtained by blasting cow carcasses with high-pressure water jets after removal of the prime cuts. Members of the government’s Spongiform Encephalopathy Advisory Committee (SEAC) complained last month that they had tried for five years to get the meat industry to provide the information.
The British Meat Manufacturers Association (BMMA) has said the information is difficult to obtain or is non-existent, although it seems only twelve premises processed MRM. A report in the Independent newspaper said the BMMA did carry out its own confidential survey in 1997, but the data was “lost during an office move”. The BMMA also says it raised the need for an official survey in 1997-98 after Labour came to power, but “it wasn’t done”.
The MRM information is vital for scientists such as epidemiologists trying to understand its role in the spread of vCJD. After a two-year investigation, the official BSE Inquiry, set up by Labour shortly after coming to office in 1997, said, it is “now clear is that this was the route by which infectious material was most likely to enter the human food chain.”
In 1989, the Conservative government banned the most highly infective tissue—brain and spinal cord—from human consumption. However, it still allowed the backbone to be used to obtain MRM, provided the slaughterhouses could guarantee 100 percent removal of the spinal cord. The BSE Inquiry pointed out that a Ministry of Agriculture report in 1990 on slaughterhouse practices “might have led one to expect such failures [of that guarantee]”. Even if the spinal cord had been removed, other infective nervous tissue such as the dorsal root ganglia would be left behind.
The government was reluctant to ban the use of MRM, arguing that meat industry profits would be affected. At that time, over 5,000 tons of MRM were produced each year, worth about £3 million.
According to the BSE Inquiry, at its meeting in August 1994, SEAC agreed not to ban the use of backbones in MRM when Ministry of Agriculture officials gave assurances that the spinal cord was being removed. At its meeting in June 1995, a ban was considered again but was postponed; one reason given was that “the impact of prohibiting the use of spinal columns on the meat industry would be enormous”. The BSE Inquiry also notes that despite assurances, some officials already realised there were “potentially serious failings” in the ability of slaughterhouses to completely remove the spinal column.
At its November 1995 meeting, SEAC learned that checks had found spinal cord contaminations on 17 separate occasions in 16 slaughterhouses, and recommended a ban on the use of cattle backbone in MRM, which the government finally implemented in December 1995. Backbones from sheep and goats were only banned in 1998. The production of MRM, mainly from chickens, still continues in enormous quantities.
The BSE Inquiry concluded that the eventual ban on using backbones to obtain MRM, “as far as preventing fragments of the spinal cord from getting into the human food chain was concerned, this was to a large extent a case of shutting the stable door” after the horse had bolted.
A related food safety issue also came to public attention last week. Doctor Richard Kimberlin, a member of SEAC for eight years, warned of the dangers of BSE in lamb. He accused the Labour government’s new Food Standards Agency of playing a potentially dangerous “waiting game” by not implementing a ban on sheep offal. Kimberlin believes BSE may have passed to sheep in the 1980s, but it has been masked by scrapie, a Spongiform disease similar to BSE, but usually non-fatal to humans. Recent experiments on sheep brains suggest that some animals originally thought to have died from scrapie could actually have died as a result of BSE. Many scientists believe that BSE possibly originated from mutations that occurred in scrapie, when sheep tissues were used in the manufacture of cattle feed. The resulting BSE could then have passed back to sheep, and consequently to humans who ate mutton.
Professor Malcolm Ferguson-Smith, who sat on the BSE Inquiry, accused the government of ignoring its recommendations and feared the 16-volume report would become “a hugely expensive doorstop”. He attacked the government’s decision to hold the foot and mouth inquiries in private, saying the “same old gang” seems to be in charge of the new Department of Environment, Food and Rural Affairs, set up in June to replace the Ministry of Agriculture, and regarded by many critics as little more than a lobby for agribusiness.