Abstract
We have taken up in detail the problem of chronic carriage of Salmonella Typhi, a major source of the microorganism's dissemination, as this carriage is asymptomatic and can last for several years. This was the case of " Typhoid Mary ", an Irish emigrant who worked as a cook in New York at the beginning of the 20th century and was responsible for several typhoid fever epidemics, so much so that, in the face of her stubborn refusal to leave her profession, the health authorities were forced to imprison her. Advances in the study of the pathophysiology of typhoid fever, and particularly of chronic carriage, soon revealed the role of the gallbladder as a reservoir, illustrating S. Typhi 's adaptation to the extreme conditions prevailing in the gallbladder, thanks to its ability to organize itself into biofilms covering the vesicular mucosa. Other factors are involved, such as the deletion of a number of chromosomal genes reflecting increasing adaptation to humans, and a battery of effectors altering innate and adaptive immune responses, including a toxin whose exact role remains a mystery.
