The story
Based on Mary Mallon (1869–1938), a notorious asymptomatic carrier of typhoid who refused to cooperate with the authorities about her condition and was subjected to forcible confinement.
Etymology from Wiktionary, CC BY-SA 4.0.
Typhoid Mary
Today it means: A person who carries and spreads a dangerous disease, especially one who refuses to cooperate to minimize the risk of infection. Full definition →