Should we eat beef?

Until the middle of the last century, the Fore Tribe in Papua New Guinea would ritualistically cannibalise their deceased relatives. Men would eat the dead tribal member’s muscle tissue while women and children would eat his or her brain. Scientists researching the tribe found that these women and children showed a high rate of a brain disease they called Kuru. Sufferers of Kuru would lose their coordination, become demented, paralysed and eventually die.

In the mid-nineties, in the United Kingdom, a disease came to light whose symptoms began with personality changes, led to dementia, paralysis and then coma leading to death. Sufferers in this country had not been devouring the brains of the deceased; they had been consuming British beef. Their disease was known as variant Creutzfeldt-Jakob Disease (vCJD). (Variant as other very rare forms had been known of beforehand; these were the sporadic form, the hereditary form and the iatrogenic form where the causing agent is transmitted via contaminated equipment.)

Variant CJD, and indeed Kuru, cause the brain to degenerate into a spongy state. They are known as Transmissible Spongiform Encephalopathies (encephalopathy – a disease of the brain). Commonly known as Mad Cow Disease, BSE is a TSE that affects cattle. The outbreak of BSE in cattle in this country in the nineties led to a small number of cases of vCJD in humans. This is what ignited the issue of whether it was safe for humans to eat beef, especially British beef as the BSE endemic was localised to this country.

It seems that the diseases are caused by a self-replicating protein known as a prion. There are normal, healthy prions and there are rogue prions, both associated with the nervous system and the brain—the reason only the women and children who ate human brain in the Fore Tribe were infected.

Farmers in the UK in the last decade are accused of (illegally) feeding their cattle animal remains which at one time or another included sheep brains. These were infected with Scrapie (another TSE, affecting sheep). Soon the cows were showing symptoms of BSE. There was a huge outbreak which politicians played down, ensuring the public that the disease could not be passed between species. However, it did in the form of variant Creutzfeldt-Jakob Disease.

Originally the link was suspected solely because of timing, however, since it has been proved that BSE and vCJD (and Kuru and Scrapie and all other TSEs) are biologically linked in that their causing agent is the same, suspected to be the prion.

The inter-species transmission of TSEs seems to have been caused by the bad practice of farmers in allowing their cattle to ingest prions in the first place in animal remains and then allowing infected beef to find its way into the human food chain. They cannot be held fully accountable for the second accusation though in that the incubation period for BSE is a few years, however, the consequences of feeding animal remains to animals that would later be used for human consumption should have been thought about.

So, is eating beef safe? Politicians have fed it to their children in front of television cameras and leading scientists have said they would never eat it. Offal and minced meat are the most likely foods that will contain the vCJD-causing agents, however, since the outbreak ten years ago they are rigorously tested. So, is consuming beef safe? I would say today it is because controls are meticulous and farmers have learned from their mistakes. Just don’t indulge in any cannibalism, especially of the brain.