Are humans infected with ‘mad cow disease’?

Written by Staff Writer by CNN Staff Writer It’s been 13 years since the first cases of vCJD cropped up in Britain, and now the country is close to determining whether we have the…

Are humans infected with 'mad cow disease'?

Written by Staff Writer by CNN Staff Writer

It’s been 13 years since the first cases of vCJD cropped up in Britain, and now the country is close to determining whether we have the first post-infection dementia.

The condition known as prion disease is caused by a rare defect in the brain and the proteins that make up prion protein are contagious. It has been suspected to spread to humans, but there’s been no evidence for it to exist before.

That, however, is changing.

A study released this week reported that 80% of those infected by prion disease already had a detectable form of the disease in their spinal fluid at the time of the first outbreak in Britain in 2003.

A small proportion of the British-bred population was infected. (Graphic Credit: The Lancet/Laurence King)

The results are based on the first study to characterize prion protein contamination in the US. The scientists’ analysis, published in the journal Nature on December 4, could, they say, help them understand how the disease spreads in humans.

“This study provides the most precise estimate of the prevalence of prion prions in the US so far, a threshold that could help inform vaccine selection for the prevention of prion disease infection,” said Michael Yupuck from the University of California at Berkeley, in a statement.

Ketan Thakkar, Director of the Centre for Vector-Borne Diseases at UCL in London, added: “If we understand how prions survive and infect nerve cells, it may help us develop better targeted interventions to prevent it from spreading. Once we understand how this disease spreads, we can target its vector.”

It also might lead to better diagnostics for those already infected.

“It’s not as though people aren’t aware of this disease,” Dr. Megan Kershner, chief of Infectious Diseases at Emory University Hospital in Atlanta, said in the release. “And when I speak to people who have had animals with it, they are willing to accept ‘mad cow disease’ and other parts of their ‘r’ word.’ But there’s such a thing as ‘mad prion disease’ and this study opens up many new questions.”

More testing needed

People at the highest risk of contracting the disease are thought to be the elderly or those with weak immune systems.

A team of scientists from Hong Kong, Canada and the US wrote in a comment article published alongside the latest study that more research is needed.

“We agree with the clinical diagnosis team (that no one has detected the genetic defect that prion disease is caused by) and in this case, the prion infections are not already fatal,” wrote researchers Mihaela M. Laboleva, Daniel Dumlao and Sara Buechley.

“Although the presence of prion protein does not yet characterize an infection, future studies on the evolution of prion protein may provide more information about this infection and its progression. There are several experimental theories and drug targets that may lead to improved diagnosis and treatment. As we learn more about the variations of prion protein, it will be easier to tailor the treatment.”

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