4. Who discovered the first known case of a typhoid carrier?

Mary Mallon (September 23, 1869 – November 11, 1938), also known as Typhoid Mary, was an Irish-born cook believed to have infected 53 people with typhoid fever, three of whom died, and the first person in the United States identified as an asymptomatic carrier of the disease pathogen, Salmonella typhi.

mary mallon

Explanation:

Mary Mallon, the first known case of a healthy carrier in the United States, was proven responsible for the contamination of at least one hundred and twenty two people, including five dead