More than 10 years after peak of the “mad cow disease” epidemic that killed more than 200 people in Europe, the threat of the fatal brain disorder caused by eating contaminated meat is still real. Thousands of Europeans are thought to be asymptomatic carriers for variant Creutzfeldt-Jakob disease, caused by misfolded proteins called prions. Because they can spread prions through blood donations, researchers have for years sought a test to safeguard blood supplies. Two papers published this week in Science Translational Medicine bring the field closer to that goal. They describe related methods for detecting prions in blood that proved highly accurate in small numbers of samples from infected people and controls.