A review of human salmonellosis: II. Duration of excretion following infection with nontyphi Salmonella.

Convalescent excretion is a common sequel to salmonella infection, but in contrast to infections with Salmonella typhi, no clear picture of the natural history of nontyphi Salmonella excretion has emerged. The literature concerning frequency and site of chronic carriage, patterns of excretion, and relationship to bacteriologic methods used for enumeration of organisms was reviewed. An examination of 32 studies including 2,814 patients who were observed after salmonella infection showed that median duration of excretion was approximately five weeks. In univariant analyses, excretion was more prolonged in children less than five years of age, persons with symptomatic infections, persons infected with serotypes other than Salmonella typhimurium, and persons studied after first onset of symptoms. Persistent excretion beyond one year occurred in fewer than 1% of subjects. Despite the large number of convalescent excretors in the community at any one time, the paucity of outbreaks in which such food handlers or hospital personnel are implicated suggests that their role in transmission of salmonella infection is small. Because convalescent excretion is so common and persistent excretion and transmission so uncommon, follow-up fecal cultures after salmonella infections are rarely necessary.