Over the past few decades, we’ve battled a number of global infectious diseases; and most of them are caused by parasites, bacteria, or viruses. And we’ve made major advances in the science of dealing with these diseases, thanks to our development of genetic tools like CRISPR and mRNA.

Far more effective than chemical agents or antibiotics, we’re now treating diseases like malaria, resistant ‘superbugs’, and coronaviruses with vaccines and gene editing, to enable our bodies to build up defences and destroy the intruders.

But there’s a new pandemic looming, caused by a tiny protein particle called a prion. Proteins are essential for the correct functioning of cells in our bodies, and are expressed by many genes in our DNA. Prions, however, are malformed or incorrectly folded proteins that cause other protein particles to bind to them and copy their structure, and can infect new hosts.

Mad cow disease and Creutzfeldt–Jakob disease are most famously caused by prions, and mostly fatal. But now there’s a new wasting disease affecting humans and animals, even pets, and scientists suspect there’s a prion behind it. The first cases were identified in south-east Asia, and local authorities are desperately trying to prevent the spread.

The biggest problem with prions is that they are naturally stable and remarkably difficult to destroy. They can even accumulate in grass, and infect grazing deer years later. Prions are resistant to heat, disinfectants and enzymes, and sterilizing surgical equipment is difficult and requires rigorous protocols.

But the biggest threat is that, unlike viruses, prions do not rely on genetic information to replicate, and can’t be broken up by the enzymes our bodies normally produce. Our new-found genetic tools may prove to be ineffective at combatting this disease. With a prion pandemic, we’ll have to rely on old-fashioned methods, like quarantine and incineration of infected material.

This time, it’s not a virus – and that makes it worse!