If you didn't already know this, I think you would find it very interesting:
What New York did about Typhoid Mary (from http://ephemeralnewyork.wordpress.com)
Mary Mallon was born in Irelend in 1869 and came to America at 16, working as a cook for wealthy families in Boston and New York. In the early 1900s, several family members came down with typhoid—a potentially deadly bacterial infection spread through food when a carrier doesn’t wash his or her hands after using the bathroom.
Eventually a New York City typhoid researcher identified Mary as the source of all the infections. She denied having typhoid, but tests proved otherwise, and city health officials forced her into quarantine in a city hospital at North Brother Island in the East River.
After leaving quarantine and promising not to handle food, she went back to work as a cook, promptly infecting more people. Eventually she was brought back to the island, where she lived out her life. Mary died in 1938, a celebrity for being a healthy carrier of a lethal bacteria.