The artifact that gave Mallon her infamous nickname "Typhoid Mary", it transfers any disease or injury the holder has to another person holding the knife at the same time.
Mary Mallon was the first person in the United States identified as a carrier of the asymptomatic pathogen associated with typhoid fever. She was presumed to have infected some 53 people, three of whom died, over the course of her career as a cook. She was forcibly isolated twice by public health authorities and died after nearly three decades altogether in isolation. Today, Typhoid Mary is a generic term for anyone who, knowingly or not, spreads something undesirable.