You catch flu by inhaling germs – now it seems you can catch prion diseases that way too.

Prions are misshapen proteins that cause brain degeneration in conditions such as mad cow disease and scrapie in animals, and Creutzfeldt–Jakob disease in humans. They can get into you if you eat infected meat or receive infected blood, but it was thought they couldn’t spread through air.

Now Adriano Aguzzi of the Swiss Federal Institute of Technology in Zurich reports that mice exposed for 10 minutes to aerosols containing as little as 2.5 per cent brain tissue from mice with scrapie all developed the disease within months. The prions didn’t need processing by the immune system first, as some other research has suggested, but entered the brain directly through nasal nerves.

“We were amazed at how efficiently they spread,” says Aguzzi. He warns that this doesn’t mean animals or people with prion diseases actually transmit them through the air: there have been no unexplained cases of disease transmission which suggested this. But workers in mills that process potentially infected carcasses may need more respiratory protection.


Labs that test for prions routinely make 10 per cent suspensions of brain tissue, and any handling – pipetting, for example – creates aerosols. Prion labs are not required to use safety equipment that protects workers from aerosols. Aguzzi, who tested his aerosols at the highest level of protection, thinks those labs may now need to rethink safety measures.

Journal reference: PLoS Pathogens, DOI: 10.1371/journal.ppat.1001257