Air may carry 'mad cow' bugs

Scientists believe it may be possible to inhale the harmful proteins thought to cause the human version of mad cow disease.

Until now it was assumed that prions could not be carried in the air like viruses.

But scientists have conducted studies in which 100 per cent of mice that inhaled prion-containing water droplets developed brain diseases.

"This previously unappreciated risk for airborne prion transmission may warrant re-thinking on biosafety guidelines in research and diagnostic laboratories," the scientists wrote in the journal Public Library of Science Pathogens.