title: Severity of infection and seasonal variation of non-typhoid Salmonella occurrence in humans.
abstract: Non-typhoid Salmonella infections may present as severe gastroenteritis necessitating hospitalization and some patients become septic with bacteraemia. We hypothesized that the seasonal variation of non-typhoid Salmonella occurrence in humans diminishes with increased severity of infection. We examined the seasonal variation of non-typhoid Salmonella infections in three patient groups with differing severity of infection: outpatients treated for gastroenteritis (n=1490); in-patients treated for gastroenteritis (n=492); and in-patients treated for bacteraemia (n=113). The study was population-based and included all non-typhoid Salmonella patients in a Danish county from 1994 to 2003. A periodic regression model was used to compute the peak-to-trough ratio for the three patient groups. The peak-to-trough ratios were 4.3 [95% confidence interval (CI) 3.6-5.0] for outpatients with gastroenteritis, 3.2 (95% CI 2.4-4.2) for in-patients with gastroenteritis, and 1.6 (95% CI 1.0-2.8) for in-patients with bacteraemia. We conclude that the role of seasonal variation diminishes with increased severity of non-typhoid Salmonella infection.
authors.affiliation: Department of Infectious Diseases, Aalborg Hospital, Aarhus University Hospital, Aalborg, Denmark. 10488@aas.nja.dk
authors.forename: K O
authors.initials: KO
authors.lastname: Gradel
authors.forename: C
authors.initials: C
authors.lastname: Dethlefsen
authors.forename: H C
authors.initials: HC
authors.lastname: Schønheyder
authors.forename: T
authors.initials: T
authors.lastname: Ejlertsen
authors.forename: H T
authors.initials: HT
authors.lastname: Sørensen
authors.forename: R W
authors.initials: RW
authors.lastname: Thomsen
authors.forename: H
authors.initials: H
authors.lastname: Nielsen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D003718:Denmark / Q000453:epidemiology; D005759:Gastroenteritis / Q000453:epidemiology / Q000382:microbiology / Q000503:physiopathology*; D006801:Humans; D008875:Middle Aged; D012044:Regression Analysis; D012475:Salmonella / Q000145:classification / Q000302:isolation & purification / Q000472:pathogenicity*; D012480:Salmonella Infections / Q000453:epidemiology / Q000382:microbiology / Q000503:physiopathology*; D012621:Seasons; D012720:Severity of Illness Index