30,000 Brits Are ‘Silent Carriers’ Of Human Mad Cow Disease

One in 2,000 people in the U.K. may carry an abnormal protein that causes human mad cow disease, according to a new study.

After taking appendix samples from 32,441 anonymous patients who had had their appendixes removed between 2000 and 2012, researchers discovered 16 that tested positive for Variant Creutzfeldt-Jakob Disease, or vCJD -- the human form of the fatal neurodegenerative disease found in cows called bovine spongiform encephalopathy, or mad cow disease. That’s about 1 in 2,000 people, or roughly 30,000 of Britain’s 60 million residents.

"These people may harbor that [vCJD] for a longer time; they may develop a different type of prion disease; they may be silent carriers," Dr. Sebastian Brandner, one of the study authors and head of the Division of Neuropathology at Queen Square, told CNN Health.

According to Live Science, it’s unclear exactly how many of these people will develop the disease, which usually sets in around age 60. Not everyone who carries the infectious protein for vCJD, called a prion, will develop the rare and fatal brain-deteriorating infection. Researchers warn, however, that carriers could pass the protein along to others through blood transfusions or surgery.

Unfortunately, there’s no blood test able to detect vCJD, and prions cannot be destroyed by ordinary sterilization methods, CNN noted. Unless surgeons use harsher, stronger sterilization procedures after every operation, they won’t even know whether they’ve exposed their instruments to vCJD contamination.

According to the U.S. Centers for Disease Control and Prevention, or CDC, there have been 227 confirmed human cases of vCJD worldwide since the first human death from mad cow disease occurred in 1996 in the U.K.

The nature of humans mad cow disease, vCJD, is still very much up for debate. According to the World Health Organization, or WHO, one theory is that the agent that causes the disease in humans is spread through consumption of cow meat contaminated with bovine tissue from the brain or other parts of the central nervous system.

Bovine spongiform encephalopathy, or BSE, is the result of an infection in a cow’s brain from a transmissible agent thought to be a modified form of a normal protein called a prion. The mutated protein affects the central nervous system of cows.

The CDC notes that the infection first appeared in cows during the 1970s, but only a few cases were identified -- until an outbreak in the U.K. occurred in the early 1990s.

By 1993, there were almost 1,000 new cases of BSE per week.

“There is strong evidence and general agreement that the outbreak was then amplified and spread throughout the United Kingdom cattle industry by feeding rendered, prion-infected, bovine meat-and-bone meal to young calves,” the CDC notes.

Fortunately, the number of cows becoming infected with mad cow disease fell over the years. In 2010, there were just 11 cases of BSE in the U.K.