August 16, 2013 -- Some people carrying chronic diseases can breeze through life, showing no symptoms of the microbes within—only to infect the people they come into contact with, occasionally with deadly results. The most infamous case of an asymptomatic disease-carrier was Typhoid Mary. In the early 1900s, Mary Mallon worked as a cook in prominent New York households. After arriving in a kitchen, however, a plague of typhoid would often sweep the household. Eventually, Mallon was forced into exile on North Brother Island on the East River, but only after she had infected around 50 people, killing three of them.
Now, researchers have come one step closer to understanding what makes some people able to carry otherwise deadly microbes without so much as a sniffle. Bacteria such as the salmonella that Mary Mallon carried, researchers found, may “hack” some of the hosts’ cells, the Los Angeles Times reports, occasionally producing asymptomatic infection.