In the mid-1980s, cattle in Britain began to fall ill with what soon came to be known as mad cow disease. From the first confirmed case in 1986 to the height of the crisis in the mid-1990s, the outbreak was linked to 232 human deaths and delivered a devastating blow to the British beef industry.

The disease and its ensuing panic led to the slaughter of more than 4.5 million cattle as prevention, and the British economy lost approximately $4.6 billion.

Discovered in Sussex in 1986, the first case of bovine spongiform encephalopathy (BSE), or mad cow disease, marked the beginning of an epidemic. Cases soared to over 420 by 1988 and, by 1993, exceeded 120,000 confirmed cases.

Mad cow disease is caused by a faulty protein that damages cow brains. Cows get sick by eating feed made from other cows, which was a common practice before the dangers were known. The practice has since ceased, according to the World Health Organization.

“The early signs of BSE in cattle included changes in behavior, such as nervousness or aggression, and physical symptoms like incoordination and difficulty standing,” says Emily Gaddam, a nurse epidemiologist and infection preventionist. “These symptoms were strange because they indicated neurological damage in animals not previously known to suffer from such conditions.”

According to the FDA, living cows can’t be tested for BSE, but post-mortem examination of brain tissue can confirm its presence.

In response to the outbreak, the British government banned the use of meat and bone meal in cattle feed and prohibited milk from affected cows in 1988. It also prohibited human consumption of offal and the U.S. halted imports of British beef.

Despite these measures, for years, British government officials asserted BSE was not a threat to humans. In May 1990, John Gummer, the country’s minister of agriculture, held a photo op during which he ate a hamburger alongside his 4-year-old daughter to assure the safety of British beef. Sir Donald Acheson, Britain’s chief medical officer, said, “Beef can be eaten safely by everyone, both adults and children, including patients in hospital.”

By 1992, three in 1,000 cows in Britain were diagnosed with mad cow disease, but Chief Medical Officer Sir Kenneth Calman still said British beef was safe in 1993, even as the outbreak was reaching its peak, with nearly 1,000 new confirmed cases each week.

Panic over mad cow disease escalated when BSE’s link to human deaths became evident. In May 1995, Stephen Churchill, a 19-year-old British man, became the first person to die from Creutzfeld Jakobs disease (vCJD), a variant of BSE. With two more vCJD deaths that year, the British government announced BSE could be transmitted to humans via the variant.

“Transmission of BSE to humans, resulting in vCJD, is believed to occur through the ingestion of cattle products contaminated with the BSE agent,” Gaddam adds. And, according to the World Health Organization, vCJD is fatal, with no treatment or cure.

Symptoms include tingling or burning sensations, psychiatric and behavioral issues, dementia and the inability to walk. All vCJD victims were exposed in countries with BSE presence in cattle.

“Most of the people who have become sick with vCJD lived in the United Kingdom at some point in their lives,” Gaddam says. “Research studies have shown that people cannot get BSE from drinking milk or eating dairy products, even if the milk came from a sick cow.

The European Union banned British beef exports in 1996, and the following year, the U.K. banned sales of beef on the bone, and Japan banned British beef and lamb (which was not lifted until 2019). In 1997, the U.S. FDA banned mammal-to-ruminant feed.

According to a June 1998 BBC report, beef sales dropped by more than a third following the March 1996 announcement linking BSE and vCJD. Although consumption eventually rebounded, the industry suffered lasting effects. The United States lifted its British beef ban only in 2020, after over two decades.

“Producers who lost much of their herds were compensated by the government but hesitated to increase their production,” NBC reported. “Consumers wanted only high-quality meats. The entire industry shrank.”

Although it made headlines in America, the mad cow outbreak didn’t have much of an impact on the U.S. beef industry. According to a 2004 report from NBC News, news of the infection found in one cow in Washington state didn’t affect retail beef sales in America.

“I think the market has a fair amount of comfort with the system we have here,” said Ron Gustafson of the U.S. Department of Agriculture’s Economic Research Service.

According to the National Veterinary Accreditation Program, part of the U.S. Department of Agriculture, BSE has been detected in upwards of 185,000 cases since 1986, with 95 percent discovered in the U.K. Five cases, one each in 2003, 2005, 2006, 2012 and 2017, have been confirmed in the United States.

Regulatory measures have made BSE rare, yet it persists. The U.K.’s Animal and Plant Health Agency noted a confirmed case in Somerset in 2021, and in 2023, a confirmed BSE case in Brazil caused several countries, including China, Iran and Russia, to ban beef sales from the nation.

“Recent cases of BSE are rare but still occur,” Gaddam says. “For instance, an atypical case of BSE was detected in a cow in South Carolina in 2023, but it posed no threat to the food supply or human health.”

Still, Gaddam says the impact of mad cow disease on the U.K. was profound, affecting not only the economy and health but also public confidence in food safety and government response to such crises.

“The measures taken have significantly reduced the incidence of BSE, but the disease remains a concern due to its potential to affect human health,” she says.