In the typhoid pandemic what did Dr. Sarah Baker find?

One of Josephine Baker’s most famous professional tasks was tracking down Mary Mallon (“Typhoid Mary”) in 1907. The way Ms. Mallon’s case was handled raises some interesting questions even today about conflicts between personal rights and public health: George Soper at the Department of Health Laboratories had investigated seven family epidemics of typhoid going back to 1900. He found that they were all linked to the cook [Mary Mallon] in each family.

I hope this helps you:)