TRUTH OR CONSEQUENCES: BSE, CJD AND HUMAN HEALTH
I have taken advice from the leading scientific and medical experts in this field. I have checked with them again today. They have consistently advised me in the past that there is no scientific justification for not eating British beef and this continues to be their advice. I therefore have no hesitation in saying that beef can be eaten safely by everyone, both adults and children, including patients in hospital.
Sir Donald Acheson, Chief Medical Officer, UK’s Department of Health
THE KURU/BSE STORY now jumps to 1988.
Despite epidemiologist John Wilesmith’s warning on how BSE was being spread, because they still believed that they were dealing with a disease that hadn’t been transmitted to humans, the UK government dragged its feet. Many officials were concerned with preventing a panic that might impact negatively on the meat-processing and beef industries. The government also knew that closing rendering plants would have placed the burden of eliminating unwanted livestock parts squarely on the shoulders of the beef industry, a significant new expense that would have resulted in higher meat costs and a concurrent decrease in the competitiveness of British beef on the world market. So, rather than demanding immediate and industry-wide changes, the politicians quietly called for the formation of a ‘blue ribbon’ panel. It was to be led by the eminent Oxford zoologist Richard Southwood, and the Southwood Working Party met for the first time on 21 June 1988 and again in November and December of that year. The problem was that neither Southwood nor his three-member team had any experience dealing with spongiform encephalopathies.
Earlier in June, government officials had met with members of the UK Renderers Association. On the strength of the data provided by Wilesmith, the ministry informed the renderers that they would be suspending the sale of ruminant-based protein (i.e. meat and bone meal) as a dietary supplement for cows and sheep. Although the ban went into place the following month, that would become the extent of the good news. Farmers were also asked to voluntarily stop feeding meat and bone meal to their cows. Unfortunately, many of them had already spent thousands of pounds on what had suddenly become an illegal nutritional supplement. But since the government hadn’t offered to buy the protein supplement back from them, and since there were no efforts to enforce the government’s request, there was little incentive for the farmers to stop using it. The results were predictable.
After acknowledging the fact that removing infected cattle from the system was an important step in curtailing BSE, the ministry did decide to compensate cattle owners who turned in their visibly sick animals. But instead of offering to purchase the diseased cattle at market value they low-balled the herd owners, offering them only 50 per cent of market value for their animals. By comparison, the government was already handing out 75 per cent of market value for cows infected with tuberculosis.
Ultimately, it’s impossible to know just how many sick cows were rushed to the slaughterhouse, but the numbers are thought to have been significant.
Until this time, there hadn’t been much publicity about what was going on and the British government made an effort to keep it that way. Their veil of secrecy might have remained in place far longer if several publications hadn’t broken the BSE story in April 1988. The industry standard, Farming News, ran a front-page headline that read ‘Spongiform Fear Grows’, while the Sunday Telegraph set the stage for the term ‘Mad Cow Disease’ with a story entitled ‘Raging Madness Attacks Cattle’. An earlier paper in Nature also demonstrated that scrapie had been experimentally transmitted from sheep to monkeys, supporting Wilesmith’s hypothesis that cows had got sick from eating scrapie-infected sheep rendered into meat and bone meal, though scientists now believe that it is more likely that BSE originated from a spontaneous mutation in cows and did not result from sheep scrapie jumping to a new species.
The Southwood Committee published its official report in February 1989. Their most important finding supported the government’s claim that they were dealing with scrapie, and so they reported that, ‘the risk of transmission of BSE to humans appears remote’. They also concluded that there was no evidence the disease was related to Creutzfeldt-Jakob disease (CJD), the rare but deadly form of human spongiform encephalopathy.
The authors of the Southwood report also painted a rosy picture for anyone concerned about the spread of BSE, predicting that it would begin to decline in the early 1990s and die out spontaneously sometime after 1996. No further effort was required. Beef was safe.
No one has ever seen a prion protein (PrP), but according to Yale neuropathologist Dr Laura Manuelidis the reason has nothing to do with size, it’s because they probably don’t exist.
Manuelidis has been researching neurodegenerative diseases for over thirty years, and she and her colleagues have performed a wide range of studies on TSEs such as Creutzfeldt-Jakob disease, kuru and BSE. Their results support a very different though far from new conclusion – that viruses are the cause. Since the name prion implies infectivity (the ability of a pathogen to establish infection), in Manuelidis’s book, clumps (or plaques) of misfolded proteins exist but since they aren’t infective, prions do not exist. According to Manuelidis, then, what is being called a prion requires a new name.
She explained that proteinaceous plaques aren’t confined to neurological disorders like kuru but are also seen in peripherally located viral diseases. ‘Conventional viruses also induce protein aggregates and amyloid fibres that are prion-like. The plaques are an end-stage product that doesn’t occur early in these infections.’ I later learned that the abnormal protein masses were also characteristic of diseases like rheumatoid arthritis and diabetes – and in none of these instances were the clumps or the proteins that comprised them transmissible.
But if these plaques aren’t pathogens and they’re not infective, what exactly are they?
According to Manuelidis, they’re a runaway defence mechanism against the infecting agent, which she believes is viral in origin.
‘When these misfolded proteins do show up, infectivity drops through the floor,’ she told me. In other words, once the body’s defences kick into gear (which ultimately leads to the production of amyloid plaques) the pathogen is less able to infect another host. The spread of the virus is curtailed.
ON 16 MAY 1990, John Gummer, the UK’s Minister of Agriculture, infamously responded to the public concerns over potentially contaminated beef in the UK by feeding a hamburger to his four-year-old daughter on the BBC television show Newsnight.
In 1993, two British dairy farmers died of CJD, a disease that was supposed to strike one out of every million people. The government stated that it was a coincidence. In May of the same year, fifteen-year-old British schoolgirl Victoria Rimmer began having trouble keeping her balance and within weeks she was falling constantly. Admitted to hospital, Rimmer underwent a battery of tests – all of which came back negative. Finally, a brain biopsy was obtained and the doctor who examined the results was stunned. Her brain was riddled with holes and amyloid plaques identical to those seen in the brains of kuru victims. With hesitancy, the physician informed Victoria’s grandmother, Beryl Rimmer, that the girl had spongiform encephalopathy – mad cow disease. What took place next was even more incredible. An investigator from the government’s CJD-surveillance unit in Edinburgh visited Mrs Rimmer, warning her not to speak out about her granddaughter’s condition, and to think of the consequences to the Common Market.
Victoria Rimmer died in November 1997. After an inquest into her death, coroner John Hughes concluded that she died of natural causes.
In 1994, a sixteen-year-old schoolgirl and an eighteen-year-old boy were diagnosed with CJD, which had hardly ever been reported in people under thirty years of age. By the following year seven people were already dead or dying.
On 8 March 1996 the hammer fell on the government’s stance in the form of a memo written by Dr Eileen Rubery, a policy maker and long-time government advisor. Rubery confirmed what others had feared for eleven years – the emergence of a new form of spongiform encephalopathy, this one transmitted to humans via the consumption of contaminated beef. She also used the dreaded ‘e’ word – epidemic. The new disease was initially referred to as sporadic CJD or atypical CJD, but scientists eventually settled on variant Creutzfeldt-Jakob disease (vCJD).
By October 2013 the number of definite and probable deaths from vCJD in the United Kingdom stood at 177. Some researchers see the epidemic as over, pointing to the fact that after peaking in 2000, when twenty-eight people in the UK died of vCJD, deaths from the disease have fallen off dramatically to three deaths in 2009, three in 2010 and one in 2013. Others believe that these 177 deaths are only the tip of the iceberg. They rationalise that because thousands of Fore died as adults, sometimes fifty years after being exposed to kuru via ritual cannibalism, many who consumed contaminated British beef in the 1970s and 80s will not have been affected yet, and might not start showing symptoms for decades after exposure.
In a 2013 study published online by the British Medical Journal, researchers tested 32,000 ‘anonymous appendix samples from people of all ages who had their appendix removed between 2000 and 2012’. Sixteen of the samples, which came from forty-one hospitals across England, tested positive for the abnormal prion protein. This translates into one carrier for every 2,000 people in the United Kingdom, or 493 people per million inhabitants, in a population of 63.5 million.
On a more positive note, scientists like Simon Mead and John Collinge, both of whom are experts in the field of kuru research, think there’s another reason why everyone exposed to prion-contaminated meat may not come down with a lethal neurodegenerative disease. As evidence they point to a common human gene (the prion protein gene or PRNP) with a worldwide distribution. The researchers and their colleagues discovered a mutated form of this gene in descendants of the Fore who survived the famous kuru outbreak. Initially, they hypothesised that this variant might have provided protection from kuru to the individuals who possessed it. These kuru-resistant survivors would have passed down their genes (and their resistance) to their descendants. In 2015 Collinge and his research team published a follow-up study in Nature in which they presented experimental evidence that when the genetic variant of PRNP was transferred to mice, it provided complete resistance to both kuru and classical CJD.
So, in a best-case scenario, at least some of the individuals consuming prion-contaminated meat in the 1980s were already resistant to the disease.1 If this is true then gloom-and-doomers may be waiting for an epidemic that never arrives. From a therapeutic viewpoint, if these genetic variants can somehow be transmitted to humans, we may one day be able to confer resistance to the pathogens that cause spongiform encephalopathies – whether they turn out to be prions or viruses.
On the other hand if Laura Manuelidis is correct and spongiform encephalopathies are the results of viruses, it would be wise to remember one of their key characteristics: viruses mutate.
Footnote
1 According to Noel Gill, lead investigator of the ‘appendix’ study, further research is now under way to determine whether prion proteins also occurred in samples from the 1970s and earlier – before the appearance of BSE in the UK. Such a finding could reduce the significance of the 2013 study, since it would suggest that prion proteins in a population do not necessarily translate to a major outbreak of spongiform encephalopathy.