Asymptomatic carrier

An asymptomatic carrier (or just carrier), is a person who is infected with an infectious disease or carries the abnormal gene of a recessive genetic disorder, but displays no symptoms. Although unaffected by the disease or the disorder themselves, carriers can transmit it to others. Mary Mallon, known as "Typhoid Mary", was an asymptomatic carrier of typhoid fever. She worked as a cook for several families in New York City at the beginning of the twentieth century. Several cases of typhoid fever in members of those families were traced to her by the Health Department. It appeared that she "carried" the infectious agent without becoming sick. There was no way of eradicating the disease and an attempt was made to restrict her from continuing to work as a cook to avoid spreading it to others.
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