Chronic Salmonella Typhi carriage at sites other than the gallbladder

Abstract

Typhoid fever caused by infection with Salmonella enterica subspecies enterica serotype Typhi (S. Typhi), an important public health problem in many low-and middle-income coun-tries, is transmitted by ingestion of water or food contaminated by feces or urine from individuals with acute or chronic S. Typhi infection. Most chronic S. Typhi carriers (shedding for 12 months) harbor infection in their gallbladder wherein preexisting pathologies, particu-larly cholelithiasis, provide an environment that fosters persistence. Much less appreciated is the existence of non-gallbladder hepatobiliary chronic S. Typhi carriers and urinary carri-ers. The former includes parasitic liver flukes as a chronic carriage risk factor. Chronic urinary carriers typically have pathology of their urinary tract, with or without renal or bladder stones. Even as the prevalence of multidrug-resistant and extensively drug-resistant S. Typhi strains is rising, global implementation of highly effective typhoid vaccines is increas-ing. There is also renewed interest in identifying, monitoring, and (where possible) treating chronic carriers who comprise the long-term reservoir of S. Typhi.