BSE is an emotive subject, so I was surprised that new research demonstrating the transmission of prions (the infectious agent that cause BSE) by aerosol, slipped out last week without furore.
The research, published in PLOS Pathogens, was carried out at the University Hospital Zurich.
It was already known that direct exposure of the nasal membranes to ground up brain infected with TSE (transmissible spongiform encephalopathy) disease would cause disease in laboratory animals. But this is the first time that a similar effect has been demonstrated when brain particles are used to prepare an aerosol.
In these experiments, the brain was reduced to extremely small particles and added to the air in an enclosed chamber containing experimental animals. The particles were present at a high concentration, such that they would reach the nasal and lung surfaces, and infection was found to spread to the animal’s brains very efficiently, possibly directly via the olfactory nerves.
There are strict controls in place to prevent BSE contaminated meat entering the food chain and BSE in cattle is now extremely rare (in 2010, almost 500,000 cattle were tested for BSE when slaughtered for human consumption in the UK and none were found to have the disease). This also means that the Zurich findings don’t raise any concerns for food safety. But what about those who work in abattoirs and slaughterhouses, including many of the Agency’s staff who are ensuring the safety of meat on our behalf?
The researchers make clear that, although they have demonstrated a potential for prions to be transmitted in the air, it does not show the likelihood of this happening in a normal environment. The experiments used very high doses of infective material within a closed environment and so the results are not directly transferable. A lot more questions need to be asked around the possible degree of exposure of staff to particles before we know if this has any implications and whether new safety measures are needed within abattoirs and meat plants.
We will be working with colleagues in our expert committees and at the Health and Safety Executive to help answer these questions.