It wasn’t until humans began dying from CJD in the UK in 1996 that the unhealthy practise of feeding cows the remains of other dead cows was acknowledged as the probable cause of this fatal neurodegenerative disease. Animal feeding practices have now been changed but CJD has a long incubation period and cases are still emerging.
Many people can remember the agricultural minister in 1990, John Gummer, cheerfully feeding his four-year-old daughter a beef burger in front of the world’s press. It was the height of the outbreak of bovine spongiform encephalopathy (BSE), commonly known as mad cow disease. The fatal neurodegenerative disease causes a spongy degeneration of the brain and spinal cord. During the 1986-1998 outbreak in the UK, more than 180,000 cattle were infected and 4.4 million were slaughtered. In 1990, fears were growing that BSE could infect humans, but Gummer hoped to convince the nation that British beef was perfectly safe.
In 1996, the worst fears were realised when the first case of the human form of the disease, Creutzfeldt-Jakob disease (CJD), was confirmed in the UK. It led to a storm of news reports, changes in government policies regarding the beef industry, a ban on exports of meat, restrictions on blood donations and a widespread fear that anyone could be infected (Diack et al., 2014).
An inquiry into BSE concluded that it was caused by cattle being fed the remains of other cattle in the form of meat and bone meal (Defra, 2000). Remember, cows are natural herbivores so it is very unnatural for them to eat the remains of other cattle. The meat and bone meal had been produced by the rendering (industrial cooking) of carcases of cattle infected with BSE. The feeding of meat and bone meal to all farmed animals was banned in 1996 and an EU-wide ban has been in place since 2001.
By 2016, CJD had killed 178 people in the UK (National Creutzfeldt-Jakob Disease Surveillance Unit, 2016). The most recent case was in 2016 when a 37-year-old man was diagnosed with the condition only two weeks before he died. It is feared that people infected with CJD may carry the disease for up to 50 years before symptoms develop. A team of researchers at the University College London studied Papua New Guineans with a related disease called kuru (a prion disease caused by cannibalism) in order to work out how long BSE may lurk in the body before it develops into CJD. They found that some Papua New Guineans, who once feasted on their own relatives, succumbed to prion disease as much as half a century later (Collinge et al., 2006).
The discovery renews concerns that CJD, could also be incubating silently and could rear its head decades from now. Professor John Collinge, who led the study, said “Recent estimates of the size of the CJD epidemic based on uniform genetic susceptibility could be substantial underestimations”. An editorial in the Lancet accompanying this study stated: “Any belief that CJD incidence has peaked and that we are now through the worst of this sinister disease must now be treated with extreme scepticism”.